We have two questions in our discussion this week.1- How does so.docx

We have two questions in our discussion this week.
1- How does socioeconomic status determine family
functioning?
2- What is the role and effect of cultural values and public
policies on the overall well-being of children and the family?
Criteria/ 300 Level Forum Rubric
Possible Points
Student Points
Initial post
Analyzed the question(s), fact(s), issue(s), etc. and provided
well-reasoned and substantive answers.
20
Supported ideas and responses using appropriate examples and
references from texts, professional and/or academic websites,
and other references. (All references must be from professional
and/or academic sources. Websites such as Wikipedia,
about.com, and others such as these are NOT acceptable.)
20
Post meets the 300 word minimum requirement and is free from
spelling/grammar errors
10
Timeliness: initial post meets the Wed deadline
10
Replies
Participated in the discussion by replying to a minimum of 2

classmates, asking a question, providing a statement of
clarification, providing a point of view with rationale,
challenging a point of discussion, or making a relationship
between one or more points of the discussion. Each reply post
is unique and original in nature and meets the required
minimum word count of 150 words
Reply #1
20
Reply #2
20
100
READING
CHFD 308 | WEEK 2
Nature and Nurture: Genetic and Environmental Foundations of
Child Development
Child development is impacted by both genetic or inherited
factors and environmental factors. Genetic factors are inherited
from both parents at the time of conception, but can be the
result of different types of gene interactions. Environmental
factors impact different ways families function and children
develop. Environmental factors include the ecological systems
that may alter family function, socio-economic status and
cultural values and public policy.
TOPICS COVERED WILL INCLUDE:
· Genetics
· Family functioning from an ecological systems perspective
· The impact of socioeconomic status
· Cultural values and public policies

“Toddler hopscotch” by Ilya Haykinson is licensed under CC
BY 2.0
The Influence of Alleles
In the argument over nature versus nurture in child
development, nature is determined by genes passed down from
parent to child during conception. Both parents pass genetic
traits to their offspring, but different offspring may acquire
different traits from each parent. Why do some children in one
family have similar characteristics or appearances and yet other
children in the same family look very different? The answer lies
in the interaction of genes inherited from the mother and father.
Genes and alleles influence the inheritance of traits, through
dominant–recessive inheritance, incomplete dominance, X-
linked inheritance, genomic imprinting, mutation, and polygenic
inheritance. In order to understand genetic inheritance, you
need to understand the basics of how genes work, and how they
work together with one another.
Fundamental Definitions
Understanding the basic structures and elements of genetics is
essential to recognize how various traits are inherited, from
appearance to intelligence.
GENE
The basic building block of the study of genetics is the gene; a
gene is a single unit of genetic information.
CHROMOSOME
A chromosome is a threadlike strand of DNA encoded with a
large number of genes. Humans receive 23 chromosomes from
each parent, for a total of 46 chromosomes.
ALLELE
An allele is one of a pair of genes that appear at a particular
location on a particular chromosome and control the same
characteristics in the individual. Humans have two alleles, one
from each parent, at each genetic locus, or position, on a
chromosome.
GENOTYPE

The entire genetic makeup of an individual is called
the genotype. The genotype can refer to the genetic makeup of
an organism with reference to a single trait, set of traits, or an
entire complex of traits. It can also refer to the sum total of
genes transmitted from parent to offspring.
PHENOTYPE
The phenotype is the appearance of an individual resulting from
the interaction of the genotype and the environment, or the
expression of the individual’s genes. You can see the phenotype
when you look at someone--the phenotype includes expressed
and observed traits. The genotype can include a range of traits
that are not expressed or observable.The phenotype is
determined by the a variety of factors, including how genes
relate to one another in the individual, and how environmental
factors impact the expression of various genes.
Patterns of Gene-Gene Interactions
Blue eyes are an example of a recessive trait
Genes interact with one another in a variety of different ways to
produce genetic traits, ranging from eye color or height to a
variety of genetic diseases. Genetic expression and inheritance
is not simple. In this lesson, you will learn about some of the
ways genes interact with one another and how their interactions
define and change the expression of genetic traits.
Dominant-Recessive Pattern
The expression of many genes is defined by whether or not a
gene is dominant or recessive. These terms describe how likely
or unlikely it is for the offspring to express this gene, or for the
genetic phenotype to appear in the offspring. Differences in the
alleles can lead to different visible traits in the individual.
The differences in the alleles can cause variations in the protein
that’s produced by the gene, or they can change protein
expression, including when, where, and how much protein is
made. Proteins affect the expression of different traits, so
variations in protein activity or expression can produce
different phenotypes.
Alleles are defined as dominant or recessive. If a dominant

allele is present, that allele will be expressed. If a recessive
allele is present, it will not be expressed if there is a dominant
allele. Dominant and recessive genes were first identified by
Gregor Mendel in the 19th century. While studying pea plants,
Mendel recognized that the color of the flowers was determined
by a dominant or a recessive gene.
The second allele in the pair of genes may be dominant as well,
if two of the dominant genes are inherited, or it can be
recessive. Think about eye color--while this is a simplified
example, many people are familiar with it and it’s a relatively
easy one to understand.
In eye color, brown eyes are dominant and blue eyes are
recessive. If one parent has two dominant brown genes,
represented by BB, all offspring will be brown eyed. If both
parents have blue eyes or bb, offspring will be blue eyed. If one
parent has brown eyes, but carries a recessive blue eye gene or
has the genotype Bb, and the other parent is blue eyed or bb, the
parents have a 50 percent chance of having a blue eyed child
and a 50 percent chance of having a brown eyed child.
While eye color really doesn’t have a significant impact, other
dominant and recessive traits can have a much greater impact on
the individual’s life and well being. Some genetic illnesses are
typically recessive traits. A healthy individual can carry the
recessive gene without expressing signs of the illness. These
individuals are called carriers. They do not express the gene,
but carry it to the next generation and may pass it to their
children. The child is only at risk if each parent carries a
recessive gene that codes for the illness. Cystic fibrosis is a
common example. If both parents have a recessive gene, the
child may be born with cystic fibrosis, even though both parents
appear healthy.
In some cases, the genetics associated with an illness of this
sort provide other benefits. For instance, sickle cell anemia is a
recessive disease that damages red blood cells. For individuals
with two recessive sickle cell genes, the illness can be
devastating. Individuals with only one copy to the recessive

sickle cell gene, however, have a much lower risk of contracting
malaria. Being a carrier offers benefits, but having two copies
of the recessive gene causes illness.
In these examples, the dominant trait, if present, will be the one
expressed. The recessive trait will only be expressed if the
individual contains two recessive alleles. While some alleles are
dominant and recessive, other alleles show different dominance
patterns, including co-dominance and incomplete dominance.
Incomplete Dominance Pattern
· INTERACTIONS BETWEEN ALLELES
· CO-DOMINANCE
· INCOMPLETE DOMINANCE
· RECOGNIZING INCOMPLETE DOMINANCE
While some alleles are dominant and recessive, other alleles
interact differently with one another. Where there are several
different allele types for a single gene, they may interact
differently with one another. They may not be dominant or
recessive, but co-dominant.
Alleles that are co-dominant produce a different phenotype than
dominant or recessive phenotypes. Blood type presents an
effective way to consider co-dominance. You’re probably aware
that there are several different blood types: A, B, O and AB. A
and B are codominant types, while O is recessive. If you have a
type O parent and a type A parent, you will be type A, as O is
recessive. If you have a type A and a type B parent, you could
end up type AB, if you inherit one type A allele and one type B
allele. Co-dominant alleles are alleles that are both expressed in
the phenotype-they are neither dominant or recessive.
Incomplete dominance allows aspects of both alleles to be
expressed in the phenotype of the individual. For instance, a red
flower that cross-breeds with a white flower might produce a
white flower, a red flower, or a pink flower. The pink flower
would be an example of incomplete dominance. If a black cat
and a white cat produced black, white and gray kittens, this
would also be an example of incomplete dominance, when the

gray kittens show traits of both the black and the white parent.
When incomplete dominance occurs, aspects of both alleles will
be expressed. Incomplete dominance may be recognized when
the offspring shows a phenotype different from both parents;
however, this is not an entirely accurate test for incomplete
dominance. The different phenotype must show traits of both
parental phenotypes.
X-linked pattern inheritance is another type of genetic
inheritance and expression. X-linked traits are found on the X
chromosome, one of two sex chromosomes. Females have two X
chromosomes, while males have one X chromosome and one Y
chromosome. X-linked traits are typically expressed only in
males, rather than females.
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· In females, the presence of one healthy functional gene and
one unhealthy, missing or defective gene on the X chromosomes
allow the healthy trait to be expressed or minimize the impact
of the unhealthy gene. In a male, the defective x-linked genes
are the only ones present, since the Y chromosome is different.
In this case, the male may present with the X-linked
inheritance.
A number of genetic disorders are x-linked, including
hemophilia, a bleeding and clotting disorder, and Fragile-X, a
disorder which causes developmental delays. Because of the X-
linked inheritance, these disorders are prevalent and more
severe in boys than in girls.
We inherit two copies of most genes and both genes are
working, functional copies. Epigenetics defines how genes are
expressed. In most cases, all epigenetic changes are stripped out
of the genes soon after conception; the parental expression of
genes does not therefore impact the offspring.
GENETIC IMPRINTING
Some genes imprint or keep the epigenetic tags during the
process of conception. Imprintation occurs in the genes found in
the egg and sperm cells before conception occurs. The imprinted

gene typically remains active, while the allele that is not
imprinted will be inactive. When this process occurs normally,
genetic development is typical.
CLONING
Epigenetic information is responsible for many of the
challenges associated with cloning mammals. Some scientists
believe that gene imprinting is the result of evolutionary
competition among males for maternal resources; or the survival
of their young over the young of other males.
· MUTATIONS
· HERITABILITY
· LIKELIHOOD OF MUTATIONS
Mutations are changes in the genetic sequence of an organism,
and they are a main cause of diversity among organisms,
particularly as expressed over time. Most mutations impact the
nucleic acids, or acids that form DNA. These changes occur at
many different levels, and they can have a range of different
consequences. Some of these mutations may be positive or
beneficial to the organism. Others may be negative, or
damaging to the organism.
For organisms that reproduce, it is essential to classify
mutations as heritable, or able to be passed down to the
offspring and descendants or not heritable. Mutations that do
not impact reproductive cells or hereditary material have little
relevance overall, but can be responsible for individual
differences. These are called somatic mutations, and do not
impact the offspring or descendants of the individual or
organism. An albino deer, for example, can be the same as other
deer except for color.
Mutations are difficult to predict; however, certain types of
mutations are more likely than others in some organisms.
Mutation rates, overall, are very low--in many cases, mutation
does not benefit the organism.
Polygenic inheritance is the interaction of different genes to
produce a single phenotype. Skin color is an example of

polygenic inheritance. Parents can pass on three different alleles
controlling skin color and the amount of melanin present in the
skin. In total, six different alleles work together to produce a
single phenotype in the individual, or to determine how light or
dark the individual’s skin is.
Some diseases are also the result of polygenic inheritance.
These are genetic illnesses, apparent at birth. Cleft palate, a
deformity in the palate of the mouth that creates an opening
between the mouth and sinuses, and spina bifida, a deformity in
the spinal development of the fetus, are the result of polygenic
inheritance.
Unlike more direct forms of inheritance, environmental issues
can directly impact polygenic inheritance. For instance, spina
bifida is a neural tube defect. The risk of this defect is lowered
if the mother has adequate supplies of folic acid in early
pregnancy.
Ecological Systems and Family Functioning
The Ecological Systems Theory, also called the Human Ecology
Theory, was formulated by psychologist Urie Bronfenbrenner.
This theory addresses the difference between behavior at home,
with family, and outside of the family. This theory strives to
explain why individuals behave differently with family than
they do at work or at school.
There are five environmental systems. Each of these involves
different environments encountered during daily life. All
environmental systems impact the child and the child’s ongoing
development.
MESOSYSTEM
The mesosystem involves relationships between different
microsystems in your life. Different microsystems relate to one
another. For instance, you might have one microsystem at
school and another with your family. Experiences in one
microsystem can impact another. For instance, a child who has a
poor home life will likely do poorly in school.
EXOSYSTEM
The exosystem is the link between a setting or context where

the individual does not have any active role, and the context
where the individual is actively participating. In the exosystem,
an external environmental system may have an impact on the
individual. The exosystem is indirect, rather than a function of
direct social interactions.
MACROSYSTEM
The macrosystem is the culture of the individual, including
ethnicity, race, socioeconomic status and conditions related to
the country of birth or origin. Someone born into poverty will
experience a very different macrosystem than someone who is
born into wealth.
CHRONOSYSTEM
The chronosystem consists of shifts and changes in the
individual’s life. Life transitions impact how the individual
functions within different environmental systems; however, the
individual may not have full control over all life shifts. For
instance, for children, the death of a parent or divorce of
parents is a significant change in the chronosystem, but not one
related to their actions.
Bronfenbrenner and Ecological Systems Theory
Bronfenbrenner believed that the child was at the center of this
progressive network of ecosystems, moving further than further
out from the child. In order to understand the child’s
development, psychologists must consider how the child
functions and interacts with each of these individual
ecosystems.
For a child of six years, microsystems might include home,
school, a sports team, and after-school child care. The
mesosystem includes the interactions between those different
microsystems. The exosystems in the child’s life might include
the parents’ workplaces. The macrosystem is the child’s culture,
determined by their socioeconomic status, ethnicity and other
factors. The chronosystem could be a variety of life events, like
the birth of a sibling.
The family, for Bronfenbrenner, plays the most critical role in
the development of the child. In the family, children learn

language, culture and values. They form lifelong bonds and
attachments in the family, and when the family is healthy, are
more capable of functioning in a healthy way in other
relationships and environments.
Parents have a direct influence on children’s behavior,
depending upon how they parent and structure the child’s
environment. Indirect influences on children are interactions
between two individuals that are impacted by an outside force
or third party. Children can experience internal or external
barriers to their relationships with different ecosystems.
Internal barriers cause worry and fear, while external barriers
are expressed as anger or aggression.
While Bronfenbrenner believed in the importance of these
ecosystems in child development, genetics still played a role in
the child’s overall experiences. Personality and other factors are
influenced by genetics. In fact, two children can experience the
same microsystem or family context in very different ways.
Awareness of the contexts in which children develop and grow
can help to understand those children, their behavior and their
development.
The Ecological Systems Theory has been key to the work of
many later psychologists, including their understanding of how
various parts of life relate to one another.
· SOCIOECONOMIC STATUS
· INCOME, EDUCATION, AND OCCUPATION
· MIXED INFLUENCES
· COMPARISON OF TWO FAMILIES
The socioeconomic status of the family significantly impacts
the physical, psychological, social and intellectual development
of children. According to the American Psychological
Association, “Socioeconomic status (SES) is often measured as
a combination of education, income and occupation. It is
commonly conceptualized as the social standing or class of an
individual or group. When viewed through a social class lens,
privilege, power and control are emphasized.”

Socioeconomic status is not just the result of income, but of a
combination of income, education and occupation. Higher
socioeconomic status is associated with higher levels of
education, technical or white-collar jobs, and higher incomes.
Lower socioeconomic status is closely associated with reduced
education, unskilled or semi-skilled labor, and lower incomes.
Each of the three factors that define socioeconomic status are
relevant to determining the socioeconomic status of a family.
Imagine a pair of young parents, both still in college or
graduate school. They have a very low income, but would not be
of low socioeconomic status because of their education and
occupation. They may have limited financial resources, but the
children likely experience some of the benefits common to
children from families with more resources. For instance, these
parents likely understand the importance of early childhood
literacy. Compare those parents to a young couple who dropped
out of high school and work menial jobs; they may have the
same approximate income as the first family, but their lives and
socioeconomic status are very different.
The differences can impact children in other ways as well. For
instance, two families of a similar income, for instance
comfortably middle class, can be very different depending upon
the parents’ occupation, experiences and education. One family
might believe it is essentially important for their children to
develop a good work ethic, while the other might be more
concerned with appearances. These differences are also the
result of socioeconomic status.
Factors Linked to Low Economic Status
Several factors are specifically linked to low socioeconomic
status. These include psychological, physical, educational, and
familial issues.
PSYCHOLOGICAL IMPACT
The psychological impact of low socioeconomic status in
childhood includes a higher risk of mental health issues,
including anxiety, depression and ADHD, increased risk of

smoking, attempted suicide, and binge drinking, as well as
higher risk of aggression and perceived threat
PHYSICAL IMPACT
The physical impact of lower socioeconomic status includes a
higher risk of obesity, stress-related illness and cardiovascular
conditions.
SCHOOL PERFORMANCE
Low socioeconomic status is correlated with reduced linguistic
understanding in kindergarten, increased school absences and
lower standardized test scores throughout school.
RISK OF VIOLENCE AND NEGLECT
Poverty is linked to an increased overall risk of family violence,
including child abuse and neglect, as well as overcrowding and
domestic violence. Children raised in poverty are also more
likely to witness or be victim to other types of crime.
RELATIONSHIP STRESS AND DIVORCE
Families with lower socioeconomic status are more likely to
experience relationship stresses, including divorce. Marriages
are more stable for couples with a higher level of education or
higher income. Increased relationship stress or divorce typically
causes stress for children, and lowers their overall
socioeconomic status.
Why does socioeconomic status have such an impact on
children’s development and well-being? What mechanisms can
help to alleviate that impact? Research since the 1930s has
clearly shown a connection between family stress and economic
hardship or low socioeconomic status. Current research findings
have consistently shown connections between lower
socioeconomic status and developmental issues for children.
Today, some 46 million Americans, or 15 percent of the
population, live below poverty level. Extreme poverty,
including homelessness, can impact a large number of children.
Some 40 percent of the homeless population is made up of
homeless youth and children; these children often suffer
extreme stress, do poorly in school, and lack adequate access to
health care and other resources.

Intervention Can Make a Positive Difference
In addition to recognizing correlation and causation between
socioeconomic issues and child development, researchers also
look at ways to address those disparities. While some steps, like
working to increase education and improve a family’s
socioeconomic status, address the cause, many interventions are
designed to reduce the impact of low socioeconomic status,
without changing the family’s socioeconomic status.
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· Several key differences are noted between higher and lower
socioeconomic status families.
· Higher status is associated with older parents, increased
interest in learning and cognitive development, and increased
support for curiosity.
· Lower status is associated with younger parents, increased
emphasis on obedience, and reduced access to cognitive
learning.
· Affluence, or wealth, may also be associated with poor child
outcomes, including poor grades and increased risk of drug and
alcohol abuse.
Early childhood interventions of different types have shown
significant improvements in outcomes for children. This
supports the causal link between low socioeconomic status and
difficulties in children. Improvements in family income
consistently improve conditions for children in those families;
however, other types of interventions can also impact children’s
well-being.
Two different theoretical concepts are applied to explain the
changes observed in children as the result of increased
socioeconomic status or early childhood intervention. The first
of these is the Family Stress Model. The Family Stress Model
suggests that children benefit from improved relationships and
reduced family stress as a result of improved family income.
In the Family Stress Model, poor outcomes associated with low
socioeconomic status are the result of increased parental stress.

Stress causes the parents to parent less effectively, damaging
their relationship with the children. Parents experiencing stress
are likely to be harsh, uninvolved, and to lack the emotional
resources necessary. As a result, the children struggle with a
variety of psychological and educational issues. The Family
Stress Model shows a direct path from indicators of economic
hardship to economic pressure, then from economic pressure to
parent emotional distress, from parent emotional distress to
conflicts between parents, from conflicts between parents to
disruptions in effective parenting behaviors, and finally from
disruptions in parenting to child maladjustment.
The second of these is the Investment Model. The Investment
Model suggests that increased economic resources allow
families to increase their investment, both financially and in
terms of time, in their children. Increased investment provides
benefits to the children, physically, psychologically,
intellectually and emotionally. These investments in children
involve multiple dimensions of family support including parent
interaction and support of learning, access to adequate food,
housing and medical care, and improved surroundings,
including living in a safe neighborhood with accessible
resources. Children have access to more resources, including
parental time, as the family’s socioeconomic status improves
Interventions in early childhood often rely upon the Investment
Model. In this case, resources are provided to parents or
children to increase the investment in the child’s learning
experiences. For instance, children might be provided with free
pre-school, increased access to books and learning materials, or
parents might have access to parenting classes and educational
resources.
Early access to learning materials, including books, is closely
correlated with educational success. Improvements in
neighborhoods and schools can also help to alleviate issues
associated with low socioeconomic status. Schools can work to
involve parents, and communities can work together to create
safe and supportive spaces.

Today, both the Family Stress Model and the Investment Model
are considered valid. The Family Stress Model may have an
increased impact on children’s emotional development and well-
being. The Investment Model appears to be more relevant with
regard to children’s cognitive development. Regardless of
socioeconomic status, families that are involved, affectionate
and warm produce healthier and happier children. This can take
many forms, but the family dinner is a popular indicator for
family closeness. Socioeconomic status can also have an impact
on family culture, and how public policies impact that culture.
Influence of Family Values and Policies
While socioeconomic status and ecological systems of family
functioning impact children, children are also impacted in a
variety of ways by the values and culture of the family, as well
as public policies regarding children. Each of these impact and
change how children develop and how they experience the world
around them.
When parents interact with children, they do more than develop
relationships. They also pass down information about culture,
values and beliefs. In addition, other adults also pass down
similar information, including teachers, care providers, doctors,
friends and family. Policymakers also have their own values,
beliefs and cultural preferences. This can cause conflicts
between parents and caregivers, as well as confusion for
children. In addition, policymakers may have different beliefs
and values than families, particularly families of lower
socioeconomic status.
CULTURE
A number of different factors can impact cultural values. What
is culture? The definition adopted by the early childhood
organization, Zero to Three is, “Culture is a shared system of
meaning, which includes values, beliefs, and assumptions
expressed in daily interactions of individuals within a group
through a definite pattern of language, behavior, customs,
attitudes, and practices”. This definition specifies several key
factors. First, culture is shared among individuals; it is not the

beliefs of a single person.
CULTURE’S CONTRIBUTIONS TO CHILD DEVELOPMENT
Culture provides tools for individuals to create scripts that they
use to engage with and understand their environment and others
in their environment. These cultural scripts become fully
ingrained; they are not conscious, but rather considered, by the
individual, to be simply the way things are. Culture is
changeable, and may develop and adapt over time. While
culture develops from interactions with the environment,
including interactions with parents and caregivers, culture is not
the same as ethnicity
IMPACT OF CAREGIVER’S CULTURE
First and foremost, individuals, particularly teachers,
caregivers, and therapeutic professionals should recognize their
own cultural perspective. For many professionals, their “culture
of origin” or culture they grew up in and perspective that they
developed is largely European American. There may be clashes
and confusion between the values of the caregiver’s culture of
origin and the parents’ and child’s culture of origin.
Subcultures
· CULTURAL DIFFERENCES
· CULTURAL SENSITIVITY
Parents and caregivers may, as the result of differing cultures of
origins, have different beliefs about many aspects of child
rearing.
· They may have a different vision of what success looks like
for the child.
· They may have differing views on well-being for the child.
· They can have varied views on behavior and discipline, and
therefore, different expectations of children’s behaviors and
interactions.
Individualist versus Independent Culture
Some broad terms can be used to define cultures. Cultures are
defined as individualist or interdependent.

INDIVIDUALISTIC CULTURE
INTERDEPENDENT (SOCIOCENTRIC) CULTURE
COMPARISON OF BOTH
PARENTS AND CHILDREN IN INDIVIDUALISTIC
CULTURE
PARENTS AND CHILDREN IN SOCIOCENTRIC CULTURE
GLOBAL CULTURE VARIATIONS
Culture’s Impact on Development
Culture can also impact language development in young
children. Multiple studies have shown that young children
develop language through exposure. Language exposure has
been linked to both culture and socioeconomic status. The
sequence of language development is the same in all languages;
however, the further development of language can depend upon
access to various resources, including conversation, books and
other learning materials. Access to language impacts children’s
vocabulary growth, vocabulary use, and IQ scores at age three.
‹1/4›
·
The cultural values of the dominant culture impact the
development and priorities of public policy, including
government funding for various issues that impact children and
often, research into child development. Many different types of
public policy impact children’s health, well-being and
development, including funding for anti-poverty programs,
access to early childhood education, and even health care
policy. Voters are predominantly older, white and economically
successful, leading to reduced access to these aid and support
for childhood programs.
Programs that provide access to job training and higher
education, improve access to food and safe housing, and that
enable regular access to healthcare can all have a beneficial
impact on child development. As noted, children in more
financially stable homes show improved intellectual and

emotional development. Programs that increase financial
stability for families with children can benefit the overall
development of those children. Cuts to these programs can
damage families and the development of children. For instance,
cuts to welfare programs and work requirements may limit
access to food and resources and increase familial stresses.
Other examples of programs like these include the school
breakfast and lunch programs. Providing free or reduced cost
meals to children at school provides them with access to
adequate and healthy food and is another example of social
welfare programs designed to address the needs of children
· Government policy also impacts the availability of early
childhood education. Childhood advocates typically recommend
broad access to early childhood education for children of all
social classes. For children of a higher socioeconomic status,
these programs have relatively little impact. These children
have access to early childhood education resources, regardless
of public policy. For children of lower socioeconomic status,
public funding for early childhood education can have a
dramatic impact on their later educational success. Federal
funding for early childhood education pays for child care
assistance, Early Head Start and Head Start preschool programs
for children of lower income families, and improvements in
elementary and secondary education.
Public Policies
· PUBLIC POLICIES ADDRESS SOCIAL PROBLEMS
· FINANCIAL HELP
· CIVIL RIGHTS OF CHILDREN
When public policy values child development and the well-
being of children, some of the differences associated with both
genetics and environmental factors can be alleviated. Good
quality childcare and early childhood education can provide
children from different cultural and socioeconomic backgrounds
with improved access to a wide variety of learning resources.

Anti-poverty programs of various sorts can reduce financial
stresses for families, and help to improve the family and child’s
socioeconomic status. Various organizations continue to work
for the well-being of children, including the Children’s Defense
Fund. This non-profit organization works for the good of
children by funding research, community activity, and
legislative activity.
The International Convention on the Rights of the Child is an
international agreement supporting basic rights of all children.
These include the right to freedom of thought and religion,
access to free and appropriate education, a loving family life,
and access to good health and an adequate standard of living.
The United States is one of only two developed countries which
have not ratified the Convention on the Rights of the Child, in
part because of the belief in individualism and rejection of legal
controls on parenting.
Sources
· American Psychological Association. (2016) Children, Youth,
Families and Socioeconomic Status. Retrieved
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families.aspx.
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genetics/variations-on-mendelian-genetics/a/polygenic-
inheritance-and-environmental-effects.
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from http://learn.genetics.utah.edu/.
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Recessive? Retrieved from http://learn.genetics.utah.edu/.
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from http://www.nature.com/scitable/topicpage/genetic-
mutation-1127.
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United States: The Influence of Culture on Early Child
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Culture-on-Early-Child-Development.aspx
· New Health Advisor. (July 1, 2016). Incomplete Dominance
Examples. Retrieved
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Examples.html
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ecological-theory/.
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urgenes/whatcausesgeneticconditions/whatisx-linkedinheritance.
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| 1
Arterial-Venous Blood Gas Testing

TABLE OF CONTENTS
INTRODUCTION 3
METHODS……………………………………………………………
…………………………………………………………………………
………3
CORRELATION BETWEEN ABG AND VBG IN CABG 4
PAIN SCORE USING 23G AND 25G NEEDLES IN ABG
ANALYSIS 4
COMPARING ABG AND VBG AMONG ICU PATIENTS 5
COMPARING ARTERIAL AND VENOUS LACTASE AMONG
CHILDREN WITH SEPSIS 6
EFFECTS OF HEPARIN IN ABG ANALYSIS 6
COMPARISON BETWEEN ARTERIAL AND CAPILLARY
SAMPLING IN ED 7
EFFECT OF STORAGE TEMPERATURE IN ABG ANALYSIS
8
COMPARING ETCO2 AND ABG IN ICU PATIENTS 8
ABG IN COPD OVER LONG
TERM…………………………………………………………………
…………………………………………..9
ABG VS VBG DIFFERENCES DURING HEMORRHAGIC
SHOCK………………………………………………………………
…….9
SUMMARY 10
REFERENCES 11
INTRODUCTION
The effectiveness of a blood gas test depends on various clinical
conditions. Though basic, a blood gas test is an essential
procedure in the diagnosis of underlying disease among critical
patients. Given the importance and the frequent clinical use of a
blood gas test in diagnostic processes, one may think that the
applicability and situational effectiveness of a blood gas test is
straightforward among respiratory therapists. Contrary to that
assumption, there are many situations such as the acceptable

temperature of the sample, time frame to analysis, and the type
of syringes used that are still unknown to many respiratory
therapists. On the other hand, there are clinical situations where
venous blood gas testing becomes effective as opposed to the
standard arterial blood gas tests. Evidently, there is a
knowledge gap among respiratory therapists when it comes to
clinical situations and the appropriateness of the blood gas test
in diagnosis particularly among the critically ill patients.
METHODS
The literature review was done using the following criteria. The
database search was through PubMed. Keywords used were
arterial blood gas, venous blood gas, and human blood gas. The
years searched were limited to 2013 to 2018. Only English
Language, peer-reviewed research articles were chosen.
CORRELATION BETWEEN ABG AND VBG IN CABG
One important aspect of a blood gas test is the collection of
blood particularly in the treatment of acute diseases. Although
arterial blood sampling is assumed to be the standard , there has
been increasing interest in the effectiveness of venous blood
sample in gas testing. Because of its effectiveness in estimating
common blood parameters such as bicarbonate, PCO2 and PO2,
the ABG has been routinely applied in the diagnosis of patients
undergoing elective Coronary Artery Bypass Graft (CABG)
surgery.1 However, the arterial procedure of collecting blood is
invasive and painful to many patients. There is also the risk of
complications including embolism, hematoma and thrombosis
besides the infections. As a result venous blood gas testing has
been suggested as an alternative method of collecting blood for
testing in CABG. According to clinical studies conducted by
Esmaeilivand, et al. venous blood gas (VBG) analysis is not an
effective replacement for ABG for measuring important blood
parameters for such as PO2 status1.The VBG is preferable
particularly in patients who have been hospitalized for lengthy
durations and have a central venous catheter, a common

occurrence among patients undergoing CABG. The advantages
associated with VBG include the limited risk of thrombosis and
embolism. It is also easier for the medical staff to perform
unlike the ABG which involves needle-stick injuries and
potential infections
PAIN SCORE USING 23G AND 25G NEEDLES IN ABG
ANALYSIS
In conducting blood gas tests, inherent risks have been raised
about the painful experiences and the risk of hepatitis when
ABG is preferred. Attempts have been made in clinical
conditions to evaluate whether the size and type of the needle
used contribute to the pain experienced by the patients.
According to Yee et al., ABG analysis is critical in the
evaluation of acid-base among patients in emergency
department. The greater risk associated with inserting needles
deeper into the skin in ABG is a drawback. However, the
researchers established that regardless of the size of the needle
used in drawing blood from the arterial sources, the resulting
differences in the pain felt whether using size 23G or 25G was
negligible. Similarly their ease or difficulty of use associated
with the either needle size on the part of the healthcare provider
was also negligible. However, size 23G needles were more
prominent in causing injuries and hematoma of the puncture
site.2
COMPARING ABG AND VBG AMONG ICU PATIENTS
According to Kim, ABG testing is commonly used in clinical
tests to evaluate the acid-base and respiratory conditions of
patients in critical situations. Like other researchers, Kim
established that ABG analysis is fraught with complications
such as reflex sympathetic dystrophy and formation of
aneurysm. The researchers established that VBG may eventually
take over from the ABG as the standard procedure in testing for
common parameters of blood gas among patients admitted in
critical care. Contrary to previous studies that questioned the
reliability of VBG test values, the more recent experiments have
confirmed concurrence of values adduced using either method in

testing particularly for testing acidosis or base component of
the blood. The effectiveness of the VBG extended to all
common parameters including bicarbonate and PCO2 among
patients in the ICU exhibiting varied pathologies. While ABG
analysis is effective in testing common parameters, the venous
procedure posse lower risks and is equally effective among
patients in the intensive care unit.3
COMPARING ARTERIAL AND VENOUS LACTASE AMONG
CHILDREN WITH SEPSIS
Early blood gas testing is a critical aspect in the treatment of
sepsis among the children. The disease is characterized by
additional demand for oxygen in the body tissues. Any
imbalance between the demand and supply of oxygen to the
blood tissues leads to hypoxia and eventually the production of
lactase. Such a critical situation brings about alteration of
homeostasis which has the potential for multiple organ injury.
Blood gas testing helps to detect the development of sepsis so
that appropriate therapeutic intervention can be administered.
Given the difficulty in drawing arterial blood among the
pediatric patients, there is a need to seek an alternative method
of assessing the pathological status of the child. According to
Fernández Sarmiento, there is a strong correlation between
central venous lactate and arterial lactate among children
suffering from sepsis. Furthermore, the study indicated that
there were no significant statistical differences between the two
approaches regarding weight, age and diagnosis.4
EFFECTS OF HEPARIN IN ABG ANALYSIS
Heparin plays an important role in arriving at accurate results
when conducting a blood gas test, using heparin prevents blood
clotting. Heparin added in syringes when conducting an ABG is
central to determining the accurate status of common parameters
among patients experiencing cardiopulmonary compromise.
Although there are several pre-analytical factors such as sample
temperature, air in the syringe and the skill of the attending
respiratory therapist, excessive heparin is central in influencing
the accuracy of blood gas tests by as much as 75%. The type of

heparin used, whether liquid or dry balanced, and the amount
used in preparing the sample, as well as the manner it is mixed
with the sample blood, is crucial in assessing correctly the
various blood parameters during the test. Although many
syringes are preloaded with the right amount and type of
heparin, there are many areas where for one or more reasons
such preloaded syringes are unavailable. Studies indicate that
the amount of heparin to be used in an ABG sample should not
exceed 0.1cc. Alternatively, flushing the syringe with heparin is
sufficient.5
COMPARISON BETWEEN ARTERIAL AND CAPILLARY
SAMPLING IN ED
Another important aspect of blood gas testing is the comparison
between capillary and arterial blood sampling. Unlike arterial,
capillary blood sampling presents reduced risks such as
ischemia and possible formation of fistula. The relevance of
collecting capillary blood samples is most significant among
patients in an emergency department. Other than the procedure
being easy to administer and less painful, studies also indicate
similarity in test outcomes when compared with ABG under
similar clinical conditions. Measures of blood gas parameters
such as pH, PO2, and HCO3 returned negligible statistical
differences between capillary and arterial blood samples (p
=0.001). The close correlation between capillary and arterial
blood samples is most significant for blood collected from the
capillaries at the fingertip and the arterial sources.6
EFFECT OF STORAGE TEMPERATURE IN ABG ANALYSIS
The reliability of a blood gas test is dependent on the storage of
the blood sample and time delay between collection and testing
of the sample. Blood gas parameters including pH and
bicarbonate are determined to a large extent by the storage
temperatures. While the importance of an ABG is unquestioned
among critically ill patients, pre-analytical determinants can

alter the accuracy of the test outcome. Studies indicate that a
delay in the analysis of the collected sample can reduce PaO2
and at the same time increase PaCO2 as a result of the
metabolism of the cell. It is therefore advisable to keep the
sample on ice if the sample testing will take more than 30
minutes. Conversely, it is not worthwhile to preserve the sample
on ice if the time between collection and blood analysis does
not exceed 30 minutes. Furthermore, where there is a delay in
carrying out the test, the respiratory therapist should be aware
of changes in gas patterns particularly where the blood samples
are taken in plastic syringes. However, when the samples are
stored in glass syringes, it is recommended to cool the blood
sample purposely to reduce the rate of metabolism of
leukocytes. This is due to the low permeability associated
withO2 molecules. On the other hand, the respiratory therapist
should be aware of the risk of overestimation of PaO2.7
COMPARING ETCO2 AND ABG IN ICU PATIENTS
According to Taghizadieh et al., capnography might be used to
determine the ETCO2 levels instead of ABG among patients
with metabolic acidosis. In studies aimed at establishing the
comparison between arterial blood bicarbonate and ETCO2
among patients with metabolic acidosis, experiments revealed
that capnography is effective for primary diagnosis where
patients are able to breathe spontaneously in the emergency
wards. However, ABG should be considered as the gold
standard in the analysis of the blood.8
ABG IN COPD OVER LONG TERM
Blood gas testing for patients with COPD must recognize the
changes in blood gases over the long term. Given the high rate
of mortality and morbidity arising from COPD, early diagnosis
could prove pivotal in effective intervention strategies. In the
studies conducted by Cukic, one common characteristic among
patients with COPD is the decline of pH and PaO2 while PaCO2
shoots up as the disease advances. This is indicative of
progressive limitation of the airflow. However, pertaining to the

patients who are on consistent therapeutic treatment, the PaO2
and PaCO2 elements were judged to be significantly smaller
when compared with not on therapy9.
ABG VS VBG DIFFERENCES DURING
HEMORRHAGIC SHOCK
In other studies conducted on rabbits, it was revealed that
hemorrhage shock leads to notable acidosis and base decline for
both venous as well as arterial blood samples. Additionally,
there was a difference in PCO2 dissimilarity between arterial
hypocarbia and venous hypercarbia.10 These results seem to
mirror previous studies that concluded that the dissimilarity
between venous and arterial blood sample was evident in cases
of severely hypoperfused states10.
SUMMARY
The suitability of the method to apply in testing blood gas is
dependent on the nature of disease as well as the state of the
patient. While ABG is the gold standard for blood gas analysis,
there are instances where VBG is equally effective yet posing
limited risks compared with ABG. Importantly, pre-analytical
conditions such as temperatures and the storage of the blood
sample are crucial in determining the accuracy of the test.
REFERENCES
1. Esmaeilivand M, Khatony A, Moradi G, Najafi F, Abdi A.
Agreement and correlation between arterial and central venous
blood gas following coronary artery bypass graft surgery. J Clin
Diagn Res. 2017 Mar;11(3):OC43–OC46.
2. Yee K, Shetty AL, Lai K. ABG needle study: a randomised
control study comparing 23G versus 25G needle success and
pain scores. Emerg Med J. 2014;7(3):254-287.
3. Kim BR, Park SJ, Shin HS, Jung YS, Rim H. Correlation
between peripheral venous and arterial blood gas measurements
in patients admitted to the intensive care unit: a single-center
study. Kidney Res Clin Pract.2013;32(1):32-38.
4. Fernández Sarmiento J, Araque P, Yepes M, Mulett H, Tovar

X, Rodriguez F. Correlation between arterial lactate and central
venous lactate in children with sepsis. Crit Care Res Pract.
2016;4(2):26-31.
5. Kumar A, Kushwah S, Sahay S. Effect of extra amount of
heparin in syringe and its effect on arterial blood gas analysis.
Euro J Med. 2015;2(6): 290-293.
6. Heidari K, Hatamabadi H, Ansarian N, Alavi-Moghaddam M,
Amini A, Safari S, Mazandarani PD, Vafaee A. Correlation
between capillary and arterial blood gas parameters in an ED.
Am J Emerg Med. 2013;1;31(2):326-329.
7. Mohammadhoseini E, Safavi E, Seifi S, Seifirad S,
Firoozbakhsh S, Peiman S. Effect of sample storage temperature
and time delay on blood gases, bicarbonate and pH in human
arterial blood samples. Iran Red Crescent Med J.
2015;17(3):435-475.
8. Taghizadieh A, Pouraghaei M, Moharamzadeh P, Ala A,
Rahmani F, Sofiani KB. Comparison of end-tidal carbon dioxide
and arterial blood bicarbonate levels in patients with metabolic
acidosis referred to emergency medicine. J Cardiovasc Thorac
Res. 2016;8(3):98–101.
9. Cukic V. The changes of arterial blood gases in COPD during
four-year period. Med Arch. 2014;68(1):14-18.
10. Williams KB, Christmas AB, Heniford BT, Sing RF,
Messick J. Arterial vs venous blood gas differences during
hemorrhagic shock. World J Crit Care Med. 2014; 3(2): 55–60.
Ashutosh et al.
European Journal of Pharmaceutical and Medical Research

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290
EFFECT OF EXTRA AMOUNT OF HEPARIN IN SYRINGE
AND ITS EFFECT ON
ARTERIAL BLOOD GAS ANALYSIS
Ashutosh Kumar
1
, Supriya Kushwah
2
and Shambhavi Sahay
3
1
Post Graduate, Department of Anaesthesia, A.J. Institute of
Medical Sciences and Research Centre, Mangalore.
2
Assistant Professor, Department of Pediatrics, Yenepoya
Medical College, Mangalore.
3

Senior Resident, Department of Pediatrics, S.M.S., Jaipur.
Article Received on 20/09/2015
Article Revised on 10/10/2015
Article Accepted on 01/11/2015
INTRODUCTION
Arterial blood gas analysis is a routine and important
procedure in emergency and intensive care unit in daily
practice specially for ventilator patients and for patients
having cardiopulmonary compromise. Arterial blood

sample can be used to measure acid-base balance,
electrolytes, gases as well as saturation simultaneously
within few minutes.
[1]
There are so many factors that
affect the accuracy of blood gas analysis upto 75%,
including preanalytical influences such as skill of
collecting sample, temperature, site of sampling, air in
the syringe, time for analysis, improper mixing, syringe
material, type and concentration of heparin.
[2-4]
Heparin influences various parametres of blood gas
analysis that varies from the type of heparin, dry
balanced vs. liquid in the preparation of the sample,
amount of heparin and its mixing with blood sample.
[5,6]
Nowadays, preloaded heparin syringes are available in
few centres. But because of non-availability of these
syringes at few places and cost factor in India, residents

and nursing staff are doing blood gas analysis by taking
varies amount of heparin in syringe. We conducted this
study to analyse the effect of heparin amount in sample
on various parameters of blood gas analysis to reduce the
preanalytical errors.
MATERIALS AND METHODS
This prospective observational study was conducted in
the Department of Anaesthesia, A.J. Institute of Medical
Sciences, Mangalore. Informed consent was taken from
all subjects before inclusion in the study. The study was
approved by the Institute Ethics Committee.
Inclusion criteria were 20 healthy adults with age
varying from 20-35 years. Exclusion criteria – subjects
with other significant history of hypertension, renal
disorder, smoking, alcohol, diabetes mellitus, any
respiratory infection, asthma, chronic obstructive
pulmonary disease, metabolic disorders, anemia were not

taken into study. Samples were collected with identical
2-cc glass syringes, using an 24 gauge needle in all the
subjects by well trained nurse. 2 samples were
withdrawn from radial artery in 2ml syringe from each
subject at an interval of 1 hour. In 1
st
sample heparin was
flushed completely from the syringe and after that
sample was taken and in 2
nd
sample 0.2ml of heparin was
preloaded and blood was taken from subjects. Both
samples were processed immediately within 5-10min
from arterial blood gas analyzer. All other preanalytical
errors i.e. temperature variation, time lag, air in syringe,
improper mixing, were ruled out. The following
parameters were noted i.e. pH, PO2, PCO2, HCO3, SaO2.
SJIF Impact Factor 2.026
Research Article

ISSN 3294-3211
EJPMR
EUROPEAN JOURNAL OF PHARMACEUTICAL
AND MEDICAL RESEARCH
www.ejpmr.com
ejpmr, 2015,2(6), 290-293
*Correspondence for Author: Dr. Ashutosh Kumar
Post Graduate, Department of Anaesthesia, A.J. Institute of
Medical Sciences and Research Centre, Mangalore 575004.
ABSTRACT
Objectives: To determine the effect of dilution of heparin on
several parameters of arterial blood gas analysis in
normal healthy subjects. Methods: We compared arterial blood
gas analysis in 2 samples of blood, 1
st
glass syringe
flushed with heparin and 2
nd
glass syringe consisted of 0.2ml of heparin collected from 20
healthy subjects.
Results: In the present study in sample-2, we observed a
significant increase in the levels of PO2 (208.5±33.6), pH

(7.49±0.039) when compared to sample-1 PO2 (88.85±6.22) and
pH (7.4±0.041), with p-value<0.0001 in both. In
sample -2 values of PCO2 (16.17±2.21), HCO3 (12.97±2.09)
were significantly low when compared to sample-1
PCO2 (40.26±3.22) and HCO3 (24.55±1.59) with p-value of
<0.0001 in both parameters. Values of oxygen
saturation were also measured but there was no significant
difference. Conclusions: Amount of heparin is an
important variable factor for arterial blood gas analysis
sampling. Extra amount of heparin can cause alteration in
pH, PO2, PCO2, HCO3, electrolytes and other parameters.
Syringes should be flushed with heparin or should
contain less than 0.1ml of heparin while analysis.
KEYWORDS: Heparin, Arterial blood gas analysis.
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Ashutosh et al.
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291

Statistical analysis was done using the SPSS version 16.0
(NY, USA). Data were expressed as mean ± standard
deviation and were analyzed using Student’s t-test. P
value of <0.05 was considered statistically significant.
RESULTS
The table shows comparison of all parameters i.e. pH,
PO2, PCO2, HCO3, SaO2 between two samples.
Arterial blood gas
parameters
Variables
Sample(1) flushed
with heparin
Sample(2) with
0.2ml heparin
P value
PO2
mean 88.85 208.5
<0.0001 Standard deviation 6.22 33.6

range 86-92 193-224
PCO2
mean 40.26 16.17
range 39-42 15-17
pH
mean 7.4 7.49
range 7.38-7.42 7.47-7.51
HCO3
mean 24.55 12.97
range 24-25 12-14
SaO2
mean 97.15 97.20
0.91 (Non-
significant)
Standard deviation 1.12 1.46
range 96.6-97.7 96.5-97.9

A increase in the pH was observed in sample 2 when
compared to sample 1(Figure-1). Both carbon dioxide
pressure and bicarbonate concentration showed an
inverse relation with the volume of heparin used. There
was a close relation between the percentage change in
each set of values for carbon dioxide pressure and actual
bicarbonate concentration from baseline and the
percentage volume of heparin in each sample (Figure-
2,3).
A increase in PO2 was observed in sample 2 (Figure-4),
while there was no significant change in values of
saturation (Figure-5).
COMPARISON OF pH BETWEEN THE GROUPS
S
A
M
P
LE
1

S
A
M
P
LE
2
6.8
7.0
7.2
7.4
7.6
7.8
8.0
p
H
Figure-1.
COMPARISON OF PCO2 BETWEEN THE GROUPS
SAMPLE 1 SAMPLE 2
0
10

20
30
40
50
P
C
O
2
(
m
m
H
g
)
Figure-2.
COMPARISON OF HCO3 BETWEEN THE GROUPS
S
A
M
P
L

E
1
S
A
M
P
L
E
2
0
10
20
30
m
E
q
/L
Figure-3.
Ashutosh et al.

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292
COMPARISON OF PO2 BETWEEN THE GROUPS
SA
M
PL
E
1
SA
M
PL
E
2
0
100
200
300
P
O
2

(m
m
H
g
)
Figure-4.
COMPARISON OF SPO2 BETWEEN THE GROUPS
S
A
M
P
L
E
1
S
A
M
P
L
E
2
85
90

95
100
105
%
S
A
T
U
R
A
T
IO
N
O
F
O
X
Y
G
E
N
Figure-5.

DISCUSSION
Arterial blood gas analysis is very important mode of
investigation to monitor ventilator patients and sick
patients. This is a routine procedure performed in ICU.
But its accuracy is affected by several factors like post-
draw metabolism, heparin, air bubble, storage,
temperature, transport, abnormal cell count, abnormal
mixing and several other factors.
Heparin, first isolated in 1916 from liver tissue, is a
naturally occurring anticoagulant present in all
mammalian species.
[7]
It is synthesized in mast cells and
basophils, and stored in the secretory granules of these
cells. Since mast cells are present in many tissue types,
heparin can be sourced from a range of extra-hepatic
tissues.
[8]
Commercial preparations are now most

commonly derived from the mucosal intima of pig
(porcine) intestine. The ideal anticoagulant should be
dry, free of interference in laboratory tests, inexpensive
and completely reliable as an anticoagulant.
[9]
The
International Federation of Clinical Chemistry
recommend for blood gas sampling, filling up of the dead
space of the syringe with heparin, to lubricate the inner
wall of the syringe, to expel the excess anticoagulant and
to collect at least 20 times the dead space volume of
blood to avoid preanalytical errors.
[10,11]
Dry balanced
heparin is “electrolyte balanced,” (containing Lithium
and Zinc rather than sodium or calcium) to prevent
interference with the numerous electrolytes and other
parameters estimated.
[12,13]
A variety of heparin salts, in

either liquid or lyophilized form, have been used as
anticoagulants. Lithium heparin, the most commonly
used anticoagulant, induces a negative bias in the
measurement of ionized calcium concentration.
[14]
Heparin is acidic and lowers pH. Heparin of lower
strength (1000 instead of 5000 units per ml) or heplock
solution should be used. Small volume of heparinised
saline just for lubricating the syringe and plunger should
be used. If volume is more, dissolved oxygen in
heparinised saline may increase PaO2.The principle
disadvantage of liquid heparin is a potential for error if
blood is over-diluted with heparin. This potential error is
due to the considerable difference in pH, pCO2, and pO2
of liquid heparin compared with that of arterial blood.
[15]
Approximate values for heparin solution are pH 6.4;
pCO2, 7.5 mmHg (1kPa), and pO2, 160 mmHg (21kPa),
reflecting the fact that heparin is an acidic solution in

equilibrium with air.
[16,17]
Heparin has two different effects on blood gas samples
based on its intrinsic chemical properties and dilution of
the sample. As heparin dilutes mainly the plasma phase
of the blood sample the magnitude of the dilution of a 1
ml blood sample by 0.05 ml of liquid heparin may be
around 10%. Siggaard Andersen found a fall in Pco2 of
16% when blood was diluted by 12-13% with saline.
When adding dry heparin to concentrations of 2, 4 and
10 mg/ml, Siggaard Andersen found that the average
effect of 1 mg heparin per ml blood was +0.1 mmHg
Pco2.
[18]
In contrast, Bradley et al. reported a 28% fall in
Pco2, at the same dilution.
[19]
Few studies have suggested that measured pH is resistant

to dilution of heparin, even if heparin and blood are
mixed in equal volumes (i.e.,50% dilution of blood),
presumably due to the buffering capacity of blood. In
some studies, no effect on pO2 was observed, while in
others, an increase in pO2 was observed at high (35% to
50%) dilution. pCO2 is the most susceptible parameter.
As long as dilution is less than 10% (e.g., 0.5 mL heparin
added to 5.0 mL of blood), pCO2 is not significantly
affected, but dilutions above 10% are associated with
significant decline in pCO2 values. There is an
approximate 1% decline in pCO2 for every 1% increase
in dilution. Calculated acid-base parameters, bicarbonate,
and base excess that are derived from measured pCO2
are affected to the same magnitude.
[20-22]
Previous studies suggest that heparin dilution also affects
Na+, K + and ionic calcium varying from − 12% to 12%.
Various authors have previously shown that estimation

of Na+, K + and Ca2 + may be low in a sample collected
for and analyzed by the blood gas machine. This has
previously been attributed to binding of cations from the
Ashutosh et al.
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293
sample by liquid heparin.
[23-25]
Previous studies are also
supportive of the fact that arterial blood sample should
be collected in appropriate conditions with minimal
amount of heparin and other prerequisite conditions to be
followed, for accurate report.
[26,27]
CONCLUSION
We recommend that no more than 0.1 cc of heparin to be

use in the syringe for arterial blood drawn or to flush the
syringe with heparin is sufficient as it will alter all
parameters. It is desirable to collect sample anaerobically
and use a glass syringe as plastic syringes are permeable
to air. The sample should be processed immediately,
preferably within 30 minutes because cells consume
oxygen and produce CO2. PaO2 varies with dilution and
can be increased also giving misconception of good
ventilation.
REFERENCES
1. Higgins C. The use of heparin in preparing samples
for blood-gas analysis. MLO Med Lab Obs., 2007;
39:16-8, 20; 22.
2. Narayanan S. The preanalytic phase. An important
component of laboratory medicine. Am J Clin
Pathol., 2000; 113; 429-52.
3. Blonshine S, Alberti R, Olesinki, RL. Procedures for
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Kidney Res Clin Pract 32 (2013) 32–38
journal homepage: http://www.krcp-ksn.com
Kidney Research and Clinical Practice
2211-9
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Contents lists available at ScienceDirect
Original Article
Correlation between peripheral venous and arterial blood gas
measurements in patients admitted to the intensive care unit:
A single-center study
Bo Ra Kim, Sae Jin Park, Ho Sik Shin n, Yeon Soon Jung, Hark
Rim
Department of Internal Medicine, Kosin University College of
Medicine, Busan, Korea
Article history:
Received 11 October 2012
Received in revised form
3 January 2013
Accepted 9 January 2013
Available online 29 January 2013

Keywords:
Bicarbonates
Blood gas analysis
Correlation
Intensive care units
132/$ - see front matter & 2013. The Ko
nse (http://creativecommons.org/licen
dx.doi.org/10.1016/j.krcp.2013.01.002
sponding author. Department of Intern
sity College of Medicine, 262 Gamcheo
2, Korea.
address: [email protected] (HS
A b s t r a c t
Background: The objective of this study was to examine the
correlation between
arterial blood gas (ABG) and peripheral venous blood gas
(VBG) samples for all
commonly used parameters in patients admitted to a medical
intensive care unit (ICU).
Methods: A single-center, prospective trial was carried out in a
medical ICU in order to
determine the level of correlation of ABG and peripheral VBG
measurements. A
maximum of five paired ABG–VBG samples were obtained per
patient to prevent a
single patient from dominating the data set.
Results: Regression equations were derived to predict arterial
values from venous
values as follows: arterial pH¼�1.108þ1.145�venous
pHþ0.008�PCO2�0.012�
venous HCO3þ0.002�venous total CO2 (R

2
¼0.655), arterial PCO2¼88.6�10.888�
venous pHþ0.150�PCO2þ0.812�venous HCO3þ0.124�venous
total CO2
(R2¼0.609), arterial HCO3¼�89.266þ12.677�venous
pHþ0.042�PCO2þ0.675�
2
¼0.782). The mean ABG minus peripheral
VBG differences for pH, PCO2, and bicarbonates were not
clinically important for
between–person heterogeneity.
Conclusion: Peripheral venous pH, PCO2, bicarbonates, and
total CO2 may be used as
alternatives to their arterial equivalents in many clinical
contexts encountered in
the ICU.
& 2013. The Korean Society of Nephrology. Published by
Elsevier. This is an open
access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
The acid–base and respiratory status of critical patients are
commonly ascertained by means of arterial blood gas (ABG)
analysis. Nevertheless, the test can cause patients to experience
discomfort, and its associated complications include arterial
injury, thrombosis or embolization, hematoma, aneurysm
rean Society of Nephrology. P
ses/by-nc-nd/4.0/).

al Medicine, Kosin
n-ro, Seo-gu, Busan,
Shin).
formation, and reflex sympathetic dystrophy [1,2]. A further
drawback for health care providers is the possibility of a needle
stick injury when performing an ABG. A comparatively safer
procedure is venous blood gas (VBG) analysis, which poses
fewer
risks to both the patients and health care professionals.
VBG may eventually take the place of ABG analysis in
determining acid–base status. In contrast to earlier studies,
which questioned the precision of VBG values [3–5], more
recent evidences indicate a concurrence of ABG and VBG
values [6–14]. However, as far as we can determine, the
correlation between all parameters typically used in arterial
and peripheral VBG samples as found in a broad population of
ublished by Elsevier. This is an open access article under the
CC BY-NC-
http://www.krcp-ksn.com
http://www.krcp-ksn.com
dx.doi.org/10.1016/j.krcp.2013.01.002
dx.doi.org/10.1016/j.krcp.2013.01.002
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Kim et al / Correlation of blood gas measurements 33
intensive care unit (ICU) patients has not been studied
previously. An earlier study investigated whether the simila-
rities between ABG and VBG values are sufficient for the
respiratory and dynamic acid–base conditions. For this eva-
luation, each patient provided multiple paired ABG and VBG
samples during the length of their ICU treatment.
The purpose of this study was to investigate the correlation
of ABG and peripheral VBG samples for all common para-
meters (bicarbonate, total CO2, pH, and PCO2) in an ICU
patient population exhibiting a variety of pathologies. Specific
attention was given to the analysis of each patient’s multiple
paired arterial and venous samples.
Table 1. Patient characteristics
Age (y; mean7standard deviation) 65.5712.4
Gender (male/female; n, %) 20 (58.8)/14 (41.2)
Intubated (n, %) 8 (23.5)
Hypotensive (n, %) 30 (88.2)
Inotropic agent use (n, %) 30 (88.2)
Primary diagnosis (n, %)
Sepsis 5 (14.7)
Upper GI bleeding 1 (2.9)
Renal failure 23 (67.6)
Pneumonia 1 (2.9)
Pancreatitis 2 (5.9)
Respiratory failure of unknown cause 2 (5.9)
GI, gastrointestinal.
Table 2. Mean7standard deviation (SD) arterial (A) and periph-
eral venous (V) blood gas values (n¼130)
Parameter ABG VBG A–V

differencea
pH 7.42670.074 7.39770.677 0.03070.050
PCO2 (mmHg) 30.876.5 34.676.9 �5.476.5
Bicarbonate (mEq/L) 20.3274.8 21.8376.94 �1.0072.75
a Total between-within-person SD. There was no significant
difference
in between-person heterogeneity in the A–V SD.
ABG, arterial blood gas; VBG, venous blood gas.
Methods
A single-center, prospective trial was performed from April
2010 to September 2010 to evaluate the correlation of ABG and
peripheral VBG measurements. The Kosin University Gospel
Hospital ICU was the site of this study. The study involved
every
adult ICU patient who was found by the treating clinician to be
in need of both ABG and peripheral VBG analysis. Cases where
informed consent could not be obtained were excluded from the
study. Samples were rejected if analysis showed them to be of
venous rather than arterial origin. The study called for only
minimal amounts of blood. Peripheral venous samples were
taken in conjunction with (and within 2 minutes of) any ICU
treatment that included an ABG analysis. ABG analysis was
performed using ABG kit (BD Critical Care Collection; Becton
Dickinson, Franklin Lakes, NJ, USA). A Nova Stat Profile CCX
Blood
Gas Analyzer (Nova Biomedical Corporation, Waltham, MA,
USA)
was used to analyze the samples. The analysis was performed as
quickly as possible after obtaining the samples. To avoid any
domination of the data set by a single patient, no more than five
paired ABG–VBG samples were taken from each patient over
5 days. A standard data collection form was used. In addition to
ABG–VBG statistics, data on primary diagnosis, intubation

status,
use of inotropic agents, hypotension (defined as a systolic blood
pressure (BP) o90 mmHg), and peripheral venous total CO2
values were obtained. Renal failure was defined as any of the
following: increase in serum creatinine by Z3.0 mg/L
(Z26.5 mmol/L) within 48 hours; increase in serum creatinine
to Z1.5 times baseline, which is known or presumed to have
occurred within the prior 7 days; or urine volume o0.5 mL/kg/h
for 6 hours. Patients’ inclusion in the study was contingent upon
their informed consent, and the Ethics Committee of Kosin
University Gospel Hospital assessed and approved the study.
Agreement between arterial (A) and peripheral venous
(V) measurements of pH, PCO2, and bicarbonate was evaluated
by the Bland–Altman method. The A–V difference was plotted
against the average value [(AþV)/2]. The A–V differences were
recorded in terms of means, standard deviations (SDs), and 95%
prediction intervals (limits of agreement), in addition to the
Pearson correlation between A–V and (AþV)/2. A correlation of
0 would indicate that no trend existed in the A–V differences.
This study describes the Pearson correlations between ABG and
peripheral VBG values. Equations for the estimation of arterial
values from peripheral venous values were ascertained using
linear regression. Components of variance computations were
performed to detect any between-patient heterogeneity, which
was necessary due to the use of multiple A and V measurements
from individual patients. Additionally, in order to determine
whether there was between–patient heterogeneity in the
regression analyses, a random slope and intercept model was
used. The sample size of 34 patients was based on estimating
the differences in peripheral venous minus arterial (lack of
agreement) and their SD to within723% with 95% confidence
for PCO2, bicarbonate, or pH differences. SPSS version 18.0
(SPSS,
Chicago, IL, USA) was used to conduct our statistical analyses.
Results were judged to be significant when the Po0.05.

Results
This study included 34 patients and a total of 151 paired
ABG–VBG samples. Twenty-one paired samples were excluded,
including 17 samples that were run on different blood gas
analyzers and four samples where the arterial and venous
samples were drawn 42 minutes apart. In total, 130 paired
samples were included in the analysis. The patient
characteristics
are shown in Table 1. The test population was made up of 20
male (58.8%) and 14 female (41.2%) patients, with a mean7SD
age of 65.5712.4 years. The most common presenting diagnosis
was renal failure (67.6%), although several other conditions that
are frequently encountered in the ICU were present. Among the
participants, none were receiving bicarbonate, although the
great
majority were hypotensive (88.2%) and on inotropic agents
(88.2%). Arterial versus peripheral venous intercept and slope
homogeneity tests for pH, PCO2, bicarbonate, and total CO2
gave
P40.05 (data not shown). Thus, all 130 observations could be
combined (see the Discussion section). Arterial pH values were
6.97–7.56, patient arterial PCO2 values 14–54 mmHg, and
arterial bicarbonate values 3–36 mEq/L. Venous pH values were
7.14–7.53, venous PCO2 values 18–52 mmHg, and venous
bicar-
bonate values 6.4–73.1 mEq/L.
Table 2 shows the mean values and SDs for arterial and
peripheral venous pH, PCO2 and bicarbonate, as well as the
arterial minus peripheral venous difference of these parameters.
There was no significant difference in between-person hetero-
geneity in the A–V SD (Table 2). Pearson correlation
coefficients

between ABG and peripheral VBG measurements are shown in
Table 3. Arterial pH, PCO2, and HCO3 were significantly corre-
lated with venous pH, PCO2, and HCO3 (P¼0.0001 for all;
correlation coefficient¼0.783, 0.705, and 0.846, respectively).
A Bland–Altman plot of arterial and peripheral venous
blood pH, PCO2, and HCO3 showing the regression line (solid
line) and the 95% limits of agreement (dotted lines) of the A–V
difference is shown in Fig. 1 [A: 0.03 (SD 0.050), 95% limit
(–0.184 to 0.311), r¼0.049, R2¼0.002, B: –5.4 (SD 6.5), 95%
limit (–0.328 to –0.006), r¼0.198, R2¼0.039, C: –1.00 (SD
2.75), 95% limit (–0.429 to 0.242), r¼�0.054, R2¼0.003]. The
correlations between VBG and ABG values for pH, PCO2, and
HCO3, between the peripheral VBG values for total CO2 and
ABG values for HCO3, and between the peripheral VBG values
for total CO2 and for HCO3 are shown in Fig. 2.
Table 3. Pearson correlation coefficients between arterial and
peripheral VBG measurements
Variable Pearson correlation coefficients P
pH 0.783 0.0001
PCO2 0.705 0.0001
HCO3 0.846 0.0001
Figure 1. Bland–Altman plot of arterial and peripheral venous
blood pH
limits of agreement (dotted lines) for the A–V difference.
r¼0.049, R2¼
An assumption of data independence about linear and multi-
ple linear regressions was confirmed by Durbin–Watson’s test
(Po0.05, data not shown). Regression equations were derived
to predict ABG values from peripheral VBG values, and are as
follows:

Arterial pH¼0.763�venous pHþ1.786 (R2¼0.544)
Arterial PCO2¼0.611�venous PCO2þ9.521 (R
2
¼0.497)
Arterial HCO3¼0.822�venous HCO3þ2.815 (R
2
¼0.716)
Arterial HCO3¼0.639�venous total CO2þ5.360 (R
2
¼0.643)
Venous HCO3¼0.750�venous total CO2þ4.134 (R
2
¼0.420)
In a subgroup analysis of renal failure patients only,
regression equations were derived to predict ABG values from
peripheral VBG values, and are as follows:
Arterial pH¼0.777�venous pHþ1.676 (R2¼0.692)
, PCO2, and HCO3 showing the regression line (solid line) and
the 95%
0.002 (A); r¼0.198, R2¼0.039 (B); r¼�0.054, R2¼0.003 (C).
Figure 2. Correlation between peripheral venous (VBG) and
arterial blood gas (ABG) values for pH, PCO2, and HCO3,
between peripheral VBG values
for total CO2 and ABG values for HCO3 and between peripheral
VBG values for total CO2 and for HCO3. R
2
¼0.544, arterial pH¼0.763 � venous

pHþ1.786 (A); R2¼0.497, arterial PCO2¼0.611�venous
PCO2þ9.521 (B); R
2
¼0.716, arterial HCO3¼0.822�venous HCO3þ2.815; (C); R
2
¼0.643, arterial
HCO3¼0.639�venous total CO2þ5.360 (D); R
2
¼0.420, venous HCO3¼0.750�venous total CO2þ4.134 (E).
Arterial PCO2¼0.651�venous PCO2þ8.157 (R
2
¼0.604)
Arterial HCO3¼0.912�venous HCO3þ0.891 (R
2
¼0.823)
Arterial HCO3¼0.725�venous total CO2þ3.317 (R
2
¼0.675)
Venous HCO3¼0.755�venous total CO2þ3.638 (R
2
¼0.772)
Multivariate regression was used to establish whether
using all four of the peripheral venous variables (pH, PCO2,
bicarbonate, and total CO2) in a single equation could
predict a patient’s acid–base and respiratory status. Arterial

pH, PCO2, HCO3 and venous total CO2 were significantly
correlated with venous pH, PCO2, and HCO3 (P¼0.0001 for
all; correlation coefficients¼0.783, 0.705, 0.846, and 0.725,
respectively). The multivariate regression equations are as
follows:
Arterial pH¼�1.108þ1.145�venous pHþ0.008�PCO2–
0.012�venous HCO3þ0.002�venous total CO2 (R
2
¼0.655)
Arterial PCO2¼88.6�10.888�venous pHþ0.150�PCO2þ
2
¼0.609)
Arterial HCO3¼�89.266þ12.677�venous pHþ0.042�PCO2þ
2
¼0.782)
In a subgroup analysis of renal failure patients only,
multivariate regression was used to establish whether using
all four of the peripheral venous variables (pH, PCO2, bicar-
bonate, and total CO2) in a single equation could be used to
predict acid–base and respiratory status. The multivariate
regression equations are as follows:
Arterial pH¼6.515þ0.117�venous pH�0.006�PCO2þ0.008�
2

¼0.773)
Arterial PCO2¼606.1–81.485�venous pH�0.797�PCO2þ
2
¼0.771)
Arterial HCO3¼443.7–59.938�venous pH�0.957�PCO2þ
2
¼0.923)
Discussion
The aim of this study was to investigate the correlation
between ABG and peripheral VBG samples for all commonly
used parameters (pH, PCO2, bicarbonate, and total CO2) in a
pathologically diverse ICU patient population. Peripheral
venous pH, PCO2, bicarbonates, and total CO2 may be corre-
lated with their arterial equivalents in many clinical contexts
encountered in the ICU.
Based on the results of this study, ABG analysis in neces-
sary in establishing precise PO2 status, just as invasive arterial
monitoring can still require arterial puncture. Nevertheless,
the use of VBG analysis can lower the amount of arterial
punctures needed for arterial sampling. In addition, the
accuracy of pulse oximetry may offer a means of ascertaining
acid–base status that is safer than ABG analysis and is also
less likely to cause patient discomfort. Some previous studies
have reported correlation between ABG and VBG values.
However, certain limitations were inherent in most of those
studies, including: examination of only one ABG and VBG
sample per patient [6–14], analysis of only one or some
parameters rather than all commonly used parameters (e.g.,
pH, PCO2, and bicarbonate), or use of specific population
samples (e.g., patients with diabetic ketoacidosis). In some

cases, concerns have even been raised about the idea of using
VBG values in place of arterial values [3–5].
Because the aim of this study was to investigate the
correlation between ABG and peripheral VBG samples, we
did not check oxygen saturation data using an oximeter.
Studies of pulse oximeter accuracy in populations of critically
ill patients have reported mixed results [15]. However, if
clinicians are aware of the bias and the wide limits of
agreement when considering saturation data from oximeter
readings in the many clinical contexts encountered in the ICU,
oximeters might one day replace the PO2 of ABG.
The presenting diagnosis for patients in the study was
predominantly renal failure (67.6%), although there was a
range of pathophysiologic parameters present. The patient
population used in this study was fairly representative of the
disease processes encountered in many medical ICUs. The
results among patients with all diagnoses and also including
only patients with renal failure were very similar (data not
shown). Therefore, we included all diagnoses in the regression
analysis. Further work is needed to study patients with other
pathophysiologic states.
The present study is the first to investigate the extent to
which a relationship between ABG and peripheral VBG pH,
PCO2, bicarbonate, and total CO2 exists across patients.
Differential CO2 unloading at the tissue level could be attrib-
uted to patients’ differing pathophysiologic states and other
aspects inherent to each patient. For these reasons, a common
relationship between ABG and peripheral VBG values in all
patients cannot be inferred. Obtaining multiple paired arterial
and peripheral venous samples from each patient allowed us
to perform homogeneity tests, which revealed that the inter-
cepts and slopes for pH, PCO2, and bicarbonate in arterial
versus venous blood had P40.05. Therefore, there was a

common relationship between ABG and peripheral VBG pH,
PCO2, bicarbonate, and total CO2 for all patients, allowing
all 130 observations to be pooled for the remainder of the
analysis.
We found excellent correlations between arterial and
peripheral venous values for pH and bicarbonate, which is
consistent with the results of previous studies [3–8,10–14]. In
terms of pH, the mean arterial minus peripheral venous
difference was 0.030 (SD 0.050) with a 95% limit of agreement
of �0.184 to 0.311 (Fig. 1A). Previous studies have shown a
mean arterial minus venous difference for pH ranging from
�0.04 to 0.05 [3–8,10,12–14]. With respect to bicarbonate,
the mean arterial minus peripheral venous difference was
�1.00 (SD 2.75) with 95% limits of agreement of �0.429 to
0.242 (Fig. 1C). Previous studies have shown a mean arterial
minus venous difference for bicarbonate ranging from �1.88
to �0.52 [3,4,6,7,11–14]. There was acceptable agreement
between arterial and peripheral venous values for PCO2; the
mean arterial minus peripheral venous difference was �5.4
(SD 6.5) with 95% limits of agreement of �0.328 to �0.006
(Fig. 1B). Previous studies found a mean arterial minus venous
difference for PCO2 ranging from �6.6 to �3.0 [3,4,6,7,11–14].
The findings of the present study were generally consistent
with earlier research in regards to PCO2. In general practice,
peripheral venous PCO2 could be used in place of arterial
PCO2,
taking into consideration that frequent serial blood gases are
generally obtained to help assess a patient’s course, and that
blood gas values should be understood in the context of the
individual patient’s clinical status. Comparing the bivariate R2
values to the multivariate R2 values shows that the multi-
variate models may account for significantly more variation
than the corresponding simple linear regression equations.
This finding demonstrates that using the more complicated

multivariate equations may be advantageous. For example, the
R2 for arterial pH using only peripheral venous pH is 0.544.
Using peripheral venous pH, peripheral venous PCO2, periph-
eral venous bicarbonate, and peripheral venous total CO2
simultaneously to predict arterial pH increased the value to
R2¼0.655.
Bicarbonate concentration is a measure that is widely used to
assess the acid–base status of patients, and can be directly
measured or derived using the Henderson–Hasselbalch equa-
tion. Bicarbonate ions make up �95% of the total carbon
dioxide
of plasma [16]; therefore, they have been used interchangeably.
Previous studies using different statistical methods to assess the
correlation between measured and calculated bicarbonate
values have shown conflicting results. Some studies have
reported strong correlations [17,18], while a recent study did
not find strong correlations between measured total CO2 and
calculated bicarbonate [19]. In our study, we found that there
was a correlation between calculated arterial bicarbonate and
measured peripheral venous total CO2 (R
2
¼0.643).
We did not obtain central venous samples, and therefore
cannot determine whether central venous samples have
acceptable correlations with ABG values. In a recent study,
data comparing central and peripheral VBG values showed
that the mean central minus peripheral differences for pH,
PCO2,
and bicarbonate were not clinically important [20]. Therefore,

we believe that central as well as peripheral venous samples
have acceptable correlations with ABG values.
The present study investigated the correlation between all
commonly used parameters in ABG and peripheral VBG
samples in ICU patients and, to the best of our knowledge,
is the first study to do so.
This study does have some limitations. First, inclusion in this
study was extended to the first 34 patients who met the
criteria. Random sampling was not used for selecting partici-
pants. However, this was not seen as a disadvantage because
our patients fit the demographic of typical ICU test populations.
Moreover, the study’s arterial and venous values covered the
range recognized as clinically important. Second, we noticed a
pervasiveness in the occurrence of renal failure, despite the fact
that test patients apparently typified the disease processes
often found in the ICU. One consequence of this was an
underrepresentation of other pathophysiologic states, such as
cardiogenic shock and hypovolemic shock. Nevertheless, unless
acute circulatory failure is present, there is little likelihood of
such pathophysiologic conditions producing a different rela-
tionship between arterial and venous values. The results of this
study can be generalized regardless of the predominance of
patients with renal failure in our population. Although this
study incorporated a wide range of acid–base status results
(including arterial pH values of 6.97–7.56, arterial PCO2 values
of 14–54 mmHg, and arterial bicarbonate values of 3–36 mEq/
L), values at the extremes were fewer in number. No more than
five samples had a pH47.5, while only two samples showed a
pHo7. Third, if peripheral circulation is poor by various causes,
results of VBG analysis should be carefully interpreted. Finally,
hypotensive status is associated with an increase in the amount
of difference between VBG and ABG analysis regarding pH and
HCO3 [21]. In this study, the amount of difference between
VBG

and ABG analysis of four normotensive patients were smaller
than that of hypotensive patients (data not shown). Studying
the precise effects of replacing ABG with VBG on the clinical
decision-making and the following outcomes is worthwhile.
In summary, peripheral venous pH, PCO2, bicarbonates,
and total CO2 may be used as alternatives to their arterial
equivalents in many clinical contexts encountered in the ICU.
More work is needed to define further the relationships
between ABG and peripheral VBG values in other pathophy-
siologic states.
Conflicts of interest
This study was supported by a grant from Roche Korea Co.,
Ltd. (2010).
Authors’ contributions
SJ Park and HS Shin participated in the design of the study
and performed the statistical analyses. YS Jung, BR Kim and
H Rim conceived the study and participated in its design
and coordination. All authors read and approved the final
manuscript.
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Correlation between peripheral venous and arterial blood gas
measurements in patients admitted to the intensive
care...IntroductionMethodsResultsDiscussionConflicts of
interestAuthors’ contributionsReferences
ABG needle study: a randomised control study
comparing 23G versus 25G needle success
and pain scores
Kenny Yee, Amith L Shetty, Kevin Lai
Westmead Hospital Emergency
Department, Westmead, New
South Wales, Australia
Correspondence to
Dr Kenny Yee, Westmead
Hospital Emergency
Department, Corner Darcy and
Hawkesbury Road, Westmead,
NSW 2145, Australia; Kenny.
[email protected]
Received 13 January 2014
Revised 15 April 2014
Accepted 17 April 2014

Published Online First
16 May 2014
To cite: Yee K, Shetty AL,
Lai K. Emerg Med J
2015;32:343–347.
ABSTRACT
Objective To determine whether a narrower gauge
needle used in ABG sampling is associated with lower pain
scores and complication rates without increasing the level
of difficulty of the procedure.
Methods We performed a prospective single-blinded
randomised control study of patients from a tertiary-level
emergency department in Sydney who required an ABG
analysis over the period of June 2010–July 2012. Patients
were randomised to either a 23G or 25G needle and the
primary outcome that included pain experienced by these
patient were recorded as pain scores on a 10 cm hatched
visual analogue scale. The difficulty scores and
complications were also noted from the operator.
Results Data for 119 consenting eligible patients were
included in the analysis. 63 patients were allocated to the
23G needle group and 56 to the 25G needle group. The
mean pain score was 3.5 (SD=2.7) for the 23G group and
3.4 (SD=2.7) for the 25G group with a mean difference
between the pain scores of 0.1 (95% CI −0.9 to 1.1,
p=0.83). The 23G and 25G mean difficulty score was 3.4
(SD=2.6) and 4.3 (SD=2.4), respectively, with a mean
difference of 0.9 (95% CI −0.03 to 1.7, p=0.06). 21.6%
of patient in the 23G needle group experienced some
complication with regard to the sampling in the form of
haematoma, tenderness or paraesthesia in comparison to
5.4% of patients in the 25G needle group (p=0.03).
Conclusions There was no significant difference in pain
scores experienced by patients undertaking ABG sampling

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