2. Blood gas components
• Blood gas components refer to the various gases
dissolved in the blood, including oxygen (O2),
carbon dioxide (CO2), and sometimes other gases
like nitrogen (N2) and hydrogen (H2). These
components play crucial roles in maintaining
acid-base balance, oxygenation of tissues, and
removal of metabolic waste products. Blood gas
analysis is a diagnostic test used to measure
these components and assess the acid-base
status and oxygenation of a patient's blood.
3. • Partial Pressure of Oxygen (PaO2):
– PaO2 represents the pressure exerted by oxygen dissolved
in the arterial blood.
– It reflects the oxygenation status of the blood and is a
critical parameter for assessing respiratory function.
• Partial Pressure of Carbon Dioxide (PaCO2):
– PaCO2 represents the pressure exerted by carbon dioxide
dissolved in the arterial blood.
– It reflects the efficiency of carbon dioxide removal by the
lungs and is a key parameter for assessing respiratory
function and acid-base balance.
• Hemoglobin: This measures the amount of hemoglobin, the
protein responsible for carrying oxygen to your cells, in your blood.
4. • pH:
– pH represents the acidity or alkalinity of the blood.
– It is maintained within a narrow range to ensure optimal
physiological function.
– Changes in pH can indicate acidosis (low pH) or alkalosis (high
pH), which can result from respiratory or metabolic
disturbances.
• Bicarbonate (HCO3-):
– Bicarbonate is a buffer in the blood that helps maintain acid-
base balance.
– It acts as a base to neutralize excess acids or as an acid to
neutralize excess bases, helping to stabilize pH.
– Changes in bicarbonate levels can indicate metabolic acidosis or
alkalosis.
5. • Oxygen Saturation (SaO2 or SPO2):
– Oxygen saturation represents the percentage of hemoglobin
molecules in arterial blood that are bound to oxygen.
– It reflects the oxygen-carrying capacity of the blood and is an
indicator of tissue oxygenation.
– Pulse oximetry (SPO2) is a non-invasive method commonly used
to estimate oxygen saturation.
• Base Excess (BE):
– Base excess represents the amount of excess or deficit of
bicarbonate in the blood compared to normal levels.
– It provides information about metabolic acid-base disturbances,
with a negative base excess indicating metabolic acidosis and a
positive base excess indicating metabolic alkalosis.
6. • Healthcare providers evaluate several conditions using an
ABG, including:
• Acute respiratory distress syndrome (ARDS): This is a life-
threatening lung injury that causes dangerously low oxygen
levels in your blood. It’s caused by sepsis, COVID-19 and
other conditions.
• Severe sepsis: Sepsis is a medical emergency caused by
your body's response to an infection and can be life-
threatening. Sepsis is the consequence of
widespread inflammation in your body.
• Septic shock: Septic shock is a life-threatening condition
that happens when your blood pressure drops to a
dangerously low level after an infection.
7. • Hypovolemic shock: Hypovolemic shock is an emergency
condition in which severe blood loss or other fluid loss
makes your heart unable to pump enough blood to your
body.
• Diabetes-related ketoacidosis (DKA): This is a serious and
life-threatening complication that affects people
with diabetes (mainly Type 1 diabetes) and those who have
undiagnosed Type 1 diabetes. It causes your blood to
become acidic.
• Renal tubular acidosis (RTA): This condition happens when
your kidneys don’t remove acids from your blood into your
urine as they should, causing your blood to become acidic.
8. • Acute respiratory failure: This happens when fluid builds
up in the air sacs in your lungs, making it difficult for your
lungs to release oxygen into your blood.
• Acute heart failure: This is a sudden weakening of your
heart that limits its function. It requires emergency
treatment to help manage and alleviate symptoms.
• Cardiac arrest: This happens when your heart suddenly
stops beating. It can happen to individuals who may or may
not have heart disease and requires immediate medical
attention.
• Asthma attack: This is a sudden worsening of asthma
symptoms caused by the tightening of muscles around your
airways.
9. • Inborn errors of metabolism: These are rare
genetic (inherited) conditions in which your
body can’t properly turn food into energy.
These conditions are usually caused by issues
with or a lack of specific proteins (enzymes)
that help break down parts of food.
11. • Collecting a blood sample for blood gas analysis
requires precision and attention to detail to ensure
accurate results.
• Gather Supplies:
• Wear appropriate personal protective equipment,
including gloves.
• Collect the necessary supplies, including a heparinized
syringe (usually 1-3 mL), alcohol swabs, gauze or cotton
balls, adhesive bandage, and a biohazard container for
sharps disposal.
• Ensure that the blood gas analyzer is calibrated and
ready for use.
12. • Patient Preparation:
• Explain the procedure to the patient and obtain
informed consent if required.
• Position the patient comfortably, typically in a
seated or semi-reclined position.
• Identify the appropriate site for arterial puncture,
usually the radial artery in the wrist or the
brachial artery in the elbow. If arterial puncture is
not feasible, a venous sample can be used,
although arterial samples are preferred for
accurate results.
13. • Cleanse the Puncture Site:
– Cleanse the puncture site with an alcohol swab and allow
it to dry completely. This helps reduce the risk of
contamination and infection.
– Avoid palpating the puncture site after cleansing to
prevent alteration of blood flow or contamination.
• Perform Arterial Puncture:
– Stabilize the artery with your non-dominant hand, using
gentle pressure to locate the pulse.
– Use aseptic technique to perform the arterial puncture
with a sterile syringe and needle. Insert the needle at a
slight angle to the skin, aiming towards the heart.
14. – Once blood flow is established, withdraw an
adequate volume of arterial blood into the
syringe. The volume required depends on the
specific requirements of the blood gas analyzer,
but it's typically around 1-3 mL.
– Avoid excessive suction or agitation during sample
collection to prevent hemolysis, which can affect
the accuracy of the results.
15. • Handle the Sample:
• Transfer the arterial blood from the syringe to a
heparinized blood gas syringe, taking care to avoid
introducing air bubbles.
• Gently mix the blood with the heparin by inverting the
syringe several times.
• Label the syringe with the patient's identification
information and the time of sample collection.
• Keep the sample at room temperature and transport it
to the laboratory for analysis as soon as possible. Blood
gas samples should be analyzed promptly to ensure
accurate results.
16. • Post-Procedure Care:
• Apply pressure to the puncture site with gauze
or cotton to prevent bleeding.
• Monitor the puncture site for signs of bleeding
or hematoma formation.
• Provide appropriate post-procedure care and
instructions to the patient.
18. • A blood gas analyzer is a medical device used
to measure various parameters in arterial and
venous blood samples, including blood gases,
electrolytes, and acid-base balance. These
analyzers are essential tools in critical care
settings, emergency departments, operating
rooms, and other areas where rapid
assessment of a patient's respiratory and
metabolic status is required.
19. Measurement Capabilities
• Blood gas analyzers can measure several
parameters, including:Partial pressure of oxygen
(PaO2)
• Partial pressure of carbon dioxide (PaCO2)
• pH
• Bicarbonate (HCO3-)
• Oxygen saturation (SaO2 or SPO2)
• Electrolytes such as sodium (Na+), potassium
(K+), and chloride (Cl-)
20. • Sample Handling System:
• Blood gas analyzers have a sample handling
system for processing blood samples obtained
from arterial or venous puncture.
• Some analyzers use capillary tubes or
cartridges to draw and handle the blood
sample, while others use syringes or sample
cups.
21. Analytical Techniques
• Blood gas analyzers use various analytical techniques to
measure different parameters, including:
• Potentiometry: Measures the voltage difference between
two electrodes in contact with the sample to determine the
concentration of ions such as pH and electrolytes.
• Amperometry: Measures the current produced by the
oxidation or reduction of a substance in the sample,
commonly used for measuring oxygen and carbon dioxide
levels.
• Spectrophotometry: Measures the absorbance of light by a
sample to quantify the concentration of specific
substances, such as hemoglobin for oxygen saturation
measurement.
22. Calibration and Quality Control:
• Blood gas analyzers require regular calibration
and quality control to ensure accurate and
reliable results.
• Calibration involves adjusting the analyzer to
ensure it measures accurately against known
standards.
• Quality control involves running control samples
with known values to verify the accuracy and
precision of the analyzer's measurements.
23. • User Interface:
• Blood gas analyzers typically have an intuitive
user interface for inputting patient
information, selecting tests, and viewing
results.
• Some analyzers may offer touchscreen
displays, built-in keyboards, or other features
to facilitate ease of use.
24. • Data Management and Connectivity:
– Many blood gas analyzers are equipped with data
management and connectivity features, allowing
results to be stored electronically, transmitted to
the hospital's electronic medical record (EMR)
system, or printed.
– Some analyzers may also have barcode scanning
capabilities for easy patient identification and
sample tracking.
25. • Maintenance and Service:
– Blood gas analyzers require regular maintenance,
including cleaning, calibration, and sensor
replacement, to ensure optimal performance.
– Service and support from the manufacturer or a
third-party provider are available for
troubleshooting, repairs, and technical assistance.
26. Results and Follow-Up
• What do the results of an arterial blood gas test mean?
• Blood test reports, including arterial blood gas test reports, usually
provide the following information:
• The name of the blood test or what was measured in your blood.
• The number or measurement of your blood test result.
• The normal measurement range for that test.
• Information that indicates if your result is normal or abnormal or
high or low.
• If your arterial blood gas test results are abnormal, it may mean
you:
• Aren’t taking in enough oxygen.
• Aren’t getting rid of enough carbon dioxide.
• Have an imbalance in your blood pH (it’s too acidic or basic).
27. What are normal values for an
arterial blood gas test?
• Normal value ranges can vary slightly from lab to lab. When you get
your blood test results back, there will be information that indicates
what that lab’s normal ranges are for each measurement. If you
have any questions about your results, be sure to ask your
healthcare provider.
• In general, normal values at sea level include:
• pH: 7.35-7.45.
• Partial pressure of oxygen (PaO2): 75 to 100 millimeters of
mercury (mmHg).
• Partial pressure of carbon dioxide (PaCO2): 35 to 45 mmHg.
• Bicarbonate (HCO3): 22 to 26 milliequivalents per liter (mEq/L).
• Oxygen saturation (O2Sat or SaO2): 95 to 100%.
• At altitudes of 3,000 feet (900 meters) and higher, the normal
oxygen level is lower.
