At the end of this session student will be able:- Describe of cardiopulmonary physiology List and describe Factor affecting tissue oxygenation Apply Oxygen administration Monitoring oxygen saturation using pulse oximetery

1. Oxygenation and ventilation(FoN)
By Mr. Gedion Zerihun
(BSc, MSc in Adult health nursing)
Post Basic Comprehensive BSc
January, 2024
Mizan-Aman, Ethiopia
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2. Outline
Introduction of cardiopulmonary physiology
Factor affecting tissue oxygenation
Oxygen administration
Monitoring oxygen saturation using pulse oximetery
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3. Objective
At the end of this session student will be able:-
Describe of cardiopulmonary physiology
List and describe Factor affecting tissue oxygenation
Apply Oxygen administration
Monitoring oxygen saturation using pulse oximetery
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4. Introduction
Oxygen is a basic human need.
The heart and lungs supply the body with oxygen necessary for
carrying out the respiratory and metabolic processes needed to
sustain life.
You will frequently care for patients who are unable to meet their
oxygenation needs.
This often results from ineffective gas exchange (lungs) or an
ineffective pump (heart).
Any condition that affects cardiopulmonary functioning directly
affects the ability of the body to meet oxygen demands.
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5. Cardiopulmonary Physiology
Respiration is the act of breathing with the exchange of oxygen and
carbon dioxide (CO2) during cellular metabolism.
This occurs through the three steps of oxygenation: ventilation,
diffusion, and perfusion.
Ventilation is the movement of air in and out of the lungs, and
Diffusion is the movement of gases between the alveoli and the
bloodstream.
The heart supports perfusion, the transport of oxygenated blood to the
cells and tissues
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6. Oxygen Transport
The delivery of oxygen to the cells and tissues depends on the amount
of oxygen entering the lungs (oxygenation) from the atmosphere, the
person’s ability to exchange gases in the alveoli, and the ability of the
heart to pump oxygenated blood to the cells and tissues.
Ventilation allows for movement of oxygen and CO2 into and out of
the lungs. Once oxygen has reached the alveoli, diffusion occurs.
Perfusion of oxygenated blood occurs in the capillary beds of the
organs and tissues.
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7. Alterations of the Pulmonary System: Factors Affecting
Ventilation and Oxygen Transport
Illnesses and conditions that affect ventilation or oxygen transport
alter respiratory functioning.
The primary alterations are hypoxia, hypoxemia, hypoventilation,
and hyperventilation.
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8. Hypoxia
Hypoxia is a state of inadequate tissue oxygenation.
Mild hypoxia stimulates peripheral chemoreceptors to increase heart
and respiration rates.
The central mechanisms that regulate breathing fail in severe hypoxia,
leading to irregular respiration, Cheyne-Stokes respiration, apnea, and
respiratory and cardiac failure.
The tissues most sensitive to hypoxia are the brain, heart, and liver.
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9. Causes of hypoxia typically include the following:
Hypoxemia, or low arterial concentrations of oxygen in the blood
Inability of the tissues to extract oxygen from the blood, as in septic
shock and cyanide poisoning
Impaired delivery of oxygen to the tissues, which can be seen in cases
of low cardiac output, sepsis, thyroid storm, or exercise.
Obstructive or restrictive pulmonary diseases
Impaired ventilation from multiple rib fractures, spinal cord injury,
neuromuscular diseases, or CNS depression resulting from
medications or overdose
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10. Signs and symptoms of hypoxia include
Tachycardia,
Tachypnea and
Dyspnea,
Peripheral vasoconstriction,
Dizziness, and
Mental confusion.
Treatment aims to correct the cause and may include oxygen
therapy, cardiac and respiratory stimulant drugs, and mechanical
ventilation
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11. Hypoxemia
Hypoxemia is an abnormal deficiency in the concentration of oxygen
in arterial blood.
Partial pressure of oxygen (PaO2) less than 60 mm Hg is typically
considered to be hypoxemic.
Chronic hypoxemia stimulates RBC production by the bone marrow,
leading to secondary polycythaemia.
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12. Causes of hypoxemia include the following:
Decreased diffusion of oxygen from the lung (alveoli) into the blood,
as in pneumonia, asthma exacerbation, or atelectasis
High altitudes
Shunting of blood from the right side of the heart to the left side
without exchange of gases in the lungs, as seen in some congenital
heart defects
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13. Symptoms of acute hypoxemia are similar to symptoms of hypoxia
and include:-
Tachypnea,
Dyspnea,
Hypertension,
Hypotension, pallor, cyanosis,
Mental status changes (e.g., headache, anxiety, impaired judgment,
confusion, euphoria, lethargy), and
Motor function changes (e.g., loss of coordination, weakness, tremors,
restlessness, stupor, coma, death
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14. Hypoxemia may also cause dysrhythmias, diaphoresis, blurred or
tunnel vision, and nausea and vomiting.
Treatment for hypoxemia includes administration of oxygen and
correction of the underlying cause.
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15. Hypoventilation
Hypoventilation occurs when ventilation is inadequate to meet the
oxygen demands of the body or to have it eliminate CO2.
It can result from a decreased respiratory rate or a breathing pattern
that is too shallow.
This results in hypoxia or hypercapnia (arterial carbon dioxide
[PaCO2] level greater than 45 mm Hg) and respiratory acidosis.
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16. Causes of hypoventilation include the following:
Impaired ventilation related to trauma, pain, infection, obstructive
diseases (emphysema or sleep apnea), or fluid volume overload
Alterations in neurological regulation of breathing, such as occurs
with head or spinal cord injuries
Alterations in chemical regulation of breathing
As ventilation decreases, PaCO2 is elevated.
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17. Clinical signs and symptoms of hypoventilation include
Dizziness,
Occipital headache on awakening,
Lethargy,
Disorientation,
Decreased ability to follow instructions,
Dysrhythmias,
Hypertension,
Seizures, and possible coma or cardiac arrest
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18. When caring for patients with COPD and hypercapnia (high CO2
levels), remember that administering excessive oxygen may result in
hypoventilation and subsequent decrease in oxygenation.
Any patient with hypoventilation may retain CO2, which leads to
respiratory acidosis and ultimately respiratory arrest.
If untreated, a patient’s status rapidly declines, and death is possible.
Treatment for hypoventilation involves treating the underlying
cause, improving tissue oxygenation, restoring ventilation, and
achieving acid-base balance
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19. Hyperventilation
Hyperventilation is an increase in respiratory rate, resulting in excess
amounts of CO2 elimination.
This causes a decrease in PaCO2, or hypocapnia, and respiratory
alkalosis.
Causes of hyperventilation include severe anxiety, infection, head
injury, medications (e.g., stimulants), and acid-base imbalance.
Acute anxiety and the subsequent increased respiratory rate may cause
loss of consciousness from excess CO2 exhalation.
An increase of 1° F in body temperature causes a 7% increase in
metabolic rate, thereby increasing CO2 production.
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20. The clinical response is increased rate and depth of respiration.
Hypoxia associated with pulmonary embolus or shock also results in
hyperventilation.
Hyperventilation produces signs and symptoms of tachycardia,
shortness of breath, chest pain, dizziness, light-headedness,
decreased concentration, paraesthesia, circumoral and/or
extremity numbness, tinnitus, blurred vision, and disorientation.
Treatment involves treating the underlying cause, improving tissue
oxygenation, restoring ventilation, reducing respiratory rate, and
achieving acid-base balance.
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21. Factors Affecting Oxygenation
Alterations in oxygenation result from
A decrease in oxygen carrying capacity of blood,
Decreased inspired oxygen concentration,
An increase in the metabolic demands of the body, and
Any alteration that affects a patient’s chest wall movement.
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22. Decreased Oxygen-Carrying Capacity
The Hgb molecule carries 97% of oxygen.
Alters Hgb, such as anemia or inhalation of toxic substances,
decreases the oxygen-carrying capacity of blood.
Acute blood loss or certain chronic diseases can result in anemia.
Carbon monoxide, a colorless and odorless gas, is a common toxic
inhalant that decreases the oxygen-carrying capacity of blood.
Carbon monoxide has a 230 to 300 times greater affinity for Hgb than
oxygen, which can create a functional hypoxemia.
Because of the strength of the bond, it is not easy for carbon
monoxide to dissociate (break away) from Hgb, making it unavailable
for oxygen transport.
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23. Decreased Inspired Oxygen Concentration
When the concentration of inspired oxygen declines, the oxygen
carrying capacity of the blood decreases.
An upper or lower airway obstruction limiting delivery of inspired
oxygen to alveoli decreases the fraction of inspired oxygen
concentration (FiO2).
Decreased environmental oxygen (the effect at high altitudes) or
decreased delivery of inspired oxygen (e.g., incorrect oxygen
concentration setting on respiratory therapy equipment) results in
decreased FiO2.
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24. Increased Metabolic Rate
Increases in metabolism increase oxygen demand.
Oxygen levels fall when the body is unable to meet an increased oxygen
demand.
An increased metabolism is a normal response of the body to pregnancy,
infection, fever, wound healing, and exercise.
In patients with increased metabolic rates, CO2 production also increases.
If the condition, such as a fever, lasts for a period of time and the metabolic
rate remains high, the body begins to break down protein stores resulting in
muscle wasting and decreased muscle mass.
Respiratory muscles such as the diaphragm and intercostals are also wasted.
The body attempts to adapt to the increased CO2 (hypercapnia) levels by
increasing the rate and depth of respiration to eliminate the excess CO2.
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25. Conditions Affecting Chest Wall Movement.
Any condition that reduces chest wall movement decreases ventilation.
If the diaphragm is unable to fully descend with breathing, the volume of
inspired air decreases, delivering less oxygen to the alveoli and
subsequently to tissues.
Musculoskeletal Abnormalities.
Thoracic abnormalities such as abnormal structural shapes and muscle
disease contribute to decreased oxygenation and ventilation.
Structural abnormalities impairing oxygenation include conditions that
affect the rib cage such as pectus excavatum and those that affect the spinal
column such as kyphosis or scoliosis.
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26. Nervous System Diseases
Myasthenia gravis and Guillain-Barré syndrome are examples of nervous system
diseases that result in hypoventilation.
These diseases impair nervous and muscular control, causing reduced ventilation
(hypoventilation)
Trauma
Trauma to the chest wall also impairs inspiration.
The patient with multiple rib fractures sometimes develops a flail chest, a life-
threatening condition in which fractures cause instability in part of the chest wall.
This causes paradoxical breathing in which the lung underlying the injured area
contracts on inspiration and expands on expiration, making ventilation ineffective.
Chest wall or upper abdominal incisions also decrease chest wall movement
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27. Developmental Factors
The age and developmental level of a patient as well as the normal
aging process can affect tissue oxygenation.
Thus you need to identify developmental risk factors in your patients.
Premature Infants
Premature infants are at risk for respiratory distress syndrome, which
is caused by surfactant deficiency and immature lung development.
When surfactant is inadequate, infants are unable to keep their alveoli
open, which impedes the exchange of respiratory gases.
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28. Infants and Toddlers
The infection rate increases in infants from 3 to 6 months of age.
Infants and toddlers are at risk for upper respiratory tract infections,
especially when they are exposed to second hand smoke or other
children.
Infants and toddlers are also at risk for airway obstruction because of
their anatomically smaller airways and their tendency to place foreign
objects in the mouth
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29. Young and Middle-Age Adults
Young and middle-age adults are exposed to many cardiopulmonary
risk factors including an unhealthy diet, lack of exercise, stress,
excessive use of highly caffeinated energy drinks, and cigarette
smoking.
Reducing these modifiable factors sometimes decreases a patient’s
risk for cardiac or pulmonary diseases.
Pregnancy causes changes in ventilation.
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30. Older Adults
The cardiac and pulmonary systems change throughout the aging
process.
Normal changes of aging place an older adult at risk for complications
in oxygenation, particularly when hospitalized.
Older adults are at increased risk for the development of influenza
and community-acquired pneumonia, which sometimes results in
death.
Because of these risks, this age-group should have the pneumonia
vaccine and an annual flu vaccine
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31. Lifestyle Factors
Patients are exposed to numerous lifestyle factors that, either alone or
in combination, affect cardiopulmonary function.
Nutrition. Good nutrition affects cardiopulmonary function by
supporting normal metabolic functions.
A poor diet leads to risk factors affecting the heart and lungs such as
obesity, hypertension, heart disease, and chronic lung disease.
Hydration. Fluid intake is essential for cellular health. Fluid intake
depends on a patient’s diet and disease processes
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32. Cont’ Lifestyle Factors
Exercise. Exercise increases metabolic activity and oxygen demand of
the body.
The rate and depth of respiration increase, enabling a person to inhale
more oxygen and exhale excess CO2.
Cigarette Smoking. Cigarette smoking is associated with heart
disease, COPD, and lung cancer
Substance Abuse. Excessive use of alcohol and other drugs impairs
tissue oxygenation.
Stress. Stress is a perceived threat that results in sympathetic
stimulation (the fight-or-flight response).
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33. Environmental Factors
The environment also influences oxygenation.
The incidence of pulmonary disease is higher in smoggy, urban areas than
in rural areas.
In addition, a patient’s workplace sometimes increases the risks for
cardiopulmonary disease.
Occupational pollutants include asbestos, talcum powder, dust, and airborne
fibers.
For example, tunnel workers exposed to dust from blasting, drilling, and
rock transport have an increased risk for developing COPD.
Construction workers may be at risk for asbestosis from asbestos exposure.
This exposure leads to pulmonary fibrosis, a restrictive lung disease, and
may lead to lung cancer
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34. Oxygen Therapy
Some patients require oxygen therapy to keep a healthy level of tissue
oxygenation.
The goal of oxygen therapy is to prevent or relieve hypoxia.
Any patient with impaired tissue oxygenation benefits from
controlled oxygen administration.
Oxygen is not a substitute for other treatments.
It is a therapeutic gas that must be prescribed and adjusted only with
a health care provider order.
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35. Oxygen Therapy cont’
Oxygen is a drug with potentially dangerous side effects including
the potential to cause hypoventilation in patients with COPD and
hypercapnia.
Continuously monitor the dosage or concentration.
Routinely check the health care provider’s orders to verify that the
patient is receiving the prescribed oxygen concentration and flow rate.
The six rights of medication administration also apply to oxygen
administration
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36. Safety Precautions With Oxygen Therapy
Oxygen is a highly combustible gas and fuels fire readily.
Although it does not spontaneously burn or cause an explosion, it can
easily cause a fire to ignite if it contacts a spark from electrical
equipment.
Follow these oxygen safety precautions:
Place an “Oxygen in Use” sign on the patient’s room door or door of house.
No smoking should be allowed on the premises.
Keep oxygen delivery systems 10 feet from any open flames.
Be sure electrical equipment in the room is functioning correctly and is
grounded.
Secure oxygen cylinders so that they do not fall over
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37. Administering oxygen
Oxygen therapy is the administration of oxygen, in concentrations
greater than those in room air to treat hypoxia.
It is important to select the correct oxygen delivery device for the
patient, i.e. how much supplementary oxygen needs to be administered
and what the patient can actually tolerate
Tissue oxygenation is dependent upon inspired oxygen, the
concentration of haemoglobin, and its ability to saturate with oxygen,
as well as the circulation of blood
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38. Indications
Indications for oxygen therapy include:
Respiratory compromise
Anaphylaxis
Shock
During anaesthesia
Post surgery
NB:- Oxygen therapy should ideally be guided by pulse oximetry.
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39. Components of oxygen therapy
Oxygen supply: e.g. piped oxygen behind the bed, oxygen
cylinder
Flowmeter: to determine oxygen flow rate in litres/minute
Oxygen tubing
Oxygen delivery mechanism: e.g. nasal cannula, non‐rebreathe
oxygen mask
Humidifier: to warm and moisten the oxygen prior to
administration
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40. Oxygen delivery system
Oxygen therapy devices
The oxygen delivery method selected depends on:
Age of the patient
Oxygen requirements/therapeutic goals
Patient tolerance to selected interface
Humidification requirements
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45. Equipment
Oxygen nasal cannula or mask as ordered by health care provider,
Oxygen tubing (consider extension tubing),
Humidifier (if indicated),
Sterile water for humidifier, face shield as needed for risk of splash,
Clean gloves if secretions are present,
Oxygen source, oxygen flowmeter,
Appropriate “oxygen in use” signs,
Pulse oximeter, stethoscope.
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46. Procedure
Ensure the patient is in an upright position to maximise breathing
Request that pulse oximetry is commenced
Check the oxygen prescription
Explain the procedure to the patient
Attach the oxygen tubing to the oxygen source
Set the oxygen flow rate
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47. Procedure cont’
Occlude the valve between the mask and the oxygen reservoir bag and
check that the reservoir bag is filling up. Remove the finger
Squeeze the oxygen reservoir bag to check the patency of the valve
between the mask and the reservoir bag. If the valve is working
correctly it will be possible to empty the reservoir bag (if the reservoir
bag does not empty, discard it and select another mask
Again occlude the valve between the mask and the oxygen reservoir
bag, allowing the reservoir bag to fill up
Place the mask with a filled oxygen reservoir bag on the patient’s
face, ensuring a tight fit
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48. Procedure cont’
Adjust the oxygen flow rate sufficiently to ensure that the reservoir bag
deflates by approximately one‐third with each breath
Provide reassurance to the patient
Closely monitor the patent’s vital signs. In particular, assess the patient’s
response to the oxygen therapy, e.g. respiratory rate, mechanics of
breathing, colour, oxygen saturation levels, and level of consciousness.
Arterial blood gas analysis will also usually be monitored
Discontinue/reduce the inspired oxygen concentration as appropriate
following advice from a suitably qualified practitioner
Document the procedure following local protocols
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49. Respiratory rate indicator
Some masks have a respiratory rate indicator to help the healthcare
practitioner to monitor the patient’s respiratory rate.
This indicator can be affected by:
The patient’s respiratory rate
Orientation of the indicator
Oxygen flow rate
Fit of the mask to the patient’s face
Presence of moisture in the indicator tube – this can actually stop
the indicator from working
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50. Oxygen humidification
Cold, dry air can increase heat and fluid loss.
Oxygen has a drying effect on the mucous membranes which can lead
to airway damage.
In addition, secretions can become thick and difficult to clear.
Humidification of long‐term oxygen therapy can help prevent these
complications.
The humidifier should always be positioned below the patient’s head.
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51. Prescription of oxygen therapy
Oxygen is a drug and should be prescribed by an appropriately
qualified practitioner.
This prescription should include:
Type of oxygen delivery system
Percentage of oxygen to be delivered (or flow rate)
Duration of oxygen therapy
Monitoring that will need to be undertaken
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52. Evidence of harm associated with oxygen therapy
There have been numerous reports of serious incidents relating to
inappropriate administration and management of oxygen; of these
incidents, poor oxygen management and other sources are:
Prescribing: failure to prescribe or wrongly prescribed
Monitoring: patients are not monitored, abnormal oxygen saturation
levels are not acted upon
Administration: confusion of oxygen with medical compressed air,
incorrect flow rates, inadvertent disconnection of supply
Equipment: empty cylinders, faulty and missing equipment
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53. Transcutaneous monitoring of oxygen saturations
Transcutaneous monitoring of oxygen saturations is also known as pulse
oximetry
The procedure involves a quick, cheap, and non‐invasive bedside monitor
which can play a vital role in the assessment of hypoxaemia
It is a method of providing an objective and continuous recording of arterial
blood oxygen saturation
The pulse oximeter probe emits light from light emitting diodes (LEDs)
through the tissue
The pulse oximeter measures oxygen saturation by calculating the ratio of
light that passes through the tissue to that which does not
This is accurate to ± 2% above a saturation of 90%
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54. Indications
Pulse oximetry can be useful as part of the assessment of:
Monitoring of acutely ill patients
Targeted oxygen therapy
Asthma/chronic obstructive pulmonary disease (COPD)
Diagnosis of sleep apnoea
Confused patients
Monitoring during general anaesthesia
NB Central cyanosis is also a sign of hypoxaemia but this only
manifests when saturations are as low as 75–80%.
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55. Cautions
Anything that interferes with the transmission of light through the
tissue may affect oxygen saturation readings.
Other errors can be caused by:
Nail varnish
Reduced pulse volume (low cardiac output, hypotension,
hypothermia)
Other haemoglobins (such as carbon monoxide, sickle cells, or
foetal haemoglobin)
Motion artefact
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56. Contraindications:- There are no contraindications
Equipment:- Pulse oximeter
Procedure for transcutaneous monitoring of oxygen saturations
Pre‐procedure
Ensure pulse oximeter is working (check battery)
Identify correct patient
Explain procedure to the patient
Wash hands
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57. Procedure
Place pulse oximeter onto patient’s finger, ensuring the digit is
fully inserted into the probe
Rest the hand with the probe on the chest at the level of the heart.
This also reduces motion artefact
Readings should be taken for 2–5minutes or it can be left on for
continuous monitoring
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58. Post‐procedure
Remove pulse oximeter from the patient’s finger
Manage the patient according to pulse oximetry findings as well as
clinical findings
Normal oxygen saturations: 94% or above
In COPD patients, saturations between 88% and 92% may be
acceptable
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59. If unable to obtain a pulse oximeter reading
Rub skin to warm up
Try a different site (different finger or ear lobe)
Use topical vasodilator
Try different machine
Reassess patient! – they may be very hypoxic, hypotensive, or
peripherally shut down
Complications:-Prolonged pulse oximetry may cause irritation or
breakdown of the tissue at the probe site
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60. Summary
Methods of oxygen Administration
Measuring oxygen saturation
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61. Thank you!!!
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