Introduction to Blood Gases

Author: Christine Wheary, MS, MLS(ASCP)
Reviewer: Roger Beckering, MEd, BA, MLT(ASCP)
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Continuing Education Credits

P.A.C.E.® Contact Hours: 1 hour(s)

Florida Board of Clinical Laboratory Science CE Credit Hours

Florida Board of Clinical Laboratory Science CE - General (Clinical Chemistry/UA/Toxicology): 1 hour(s)

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Objectives

  • Define pH using the Henderson-Hasselbalch equation and its relationship to the acid/base balance in the body.
  • State the normal HCO3-/H+ ratio and its significance to body pH.
  • Discuss the behavior of pO2 and pCO2 gases in the lungs and the tissues under normal and abnormal conditions.
  • Define respiratory and metabolic/non-respiratory acidosis/alkalosis and the organ involved in the regulation of each type.
  • Explain the mechanism and the need for compensation as related to blood pH.
  • Identify respiratory versus metabolic/non-respiratory acidosis/alkalosis when presented with value sets for pH, HCO3-, and pCO2.
  • Discuss the proper procedure for collection and handling of samples for blood gases.

Course Outline

  • Introduction
    • Blood Gas Analysis
  • Definitions
    • Acid
    • Base
    • pH
    • Buffer
    • A substance that can yield hydroxide ions (OH-) is defined as a(n):
  • pH and Acid/Base Balance
    • Henderson-Hasselbalch Equation
  • Buffer Systems
    • Bicarbonate/Carbonic Acid System
    • Phosphate System
    • Plasma Proteins
  • Regulation of Acid/Base Balance
    • Elimination of CO2 via Ventilation
    • Reclamation of HCO3 from Glomerular Filtrate
    • In the lungs, the blood pH is affected via:
  • Oxygen and Gas Exchange
    • Oxygen and Carbon Dioxide
      • Conditions Necessary for Tissue Oxygenation
      • Factors Influencing Oxygen that Moves Through the Lungs and Tissue
    • Oxygen Transport
      • Hemoglobin-Oxygen Dissociation
      • Factors That Affect the Oxygen Dissociation Curve
      • We evaluate oxygen status by measuring which of the following three parameters in a blood gas analysis?
    • Blood Gas Measurements
      • Values
    • Assessment of Acid/Base Homeostasis
      • Acidemia/Alkalemia
        • Nonrespiratory/Metabolic Acidosis
        • Respiratory Acidosis
        • Nonrespiratory/Metabolic Alkalosis
        • Respiratory Alkalosis
        • True or False: Respiratory acidosis results from either a loss of bicarbonate or an increase in organic acids, such as lactic acid or ketoacids, causing a decrease in the blood pH.
      • Acidosis/Alkalosis Examples
        • Acidosis/Alkalosis Examples
        • Acidosis/Alkalosis Summary
        • Consider the following values from an arterial blood gas analysis:Patient ResultReference RangepH7.307.35-7.45pCO23635-45 mmHgHCO3-1822-26 mmol/LWhat is your interpretation of these ABG values?
      • Physical Conditions/Disease States that Cause/Result in Acidosis/Alkalosis
        • Nonrespiratory/Metabolic Acidosis
        • Nonrespiratory/Metabolic Alkalosis
        • True or False: A loss of acidic fluids can cause diabetic ketoacidosis, a type of nonrespiratory/metabolic acidosis.
        • Respiratory Acidosis
        • Respiratory Alkalosis
        • True or False: Hyperventilation from anxiety or nervousness can cause an increased elimination of CO2 by the lungs, resulting in respiratory alkalosis.
        • Table 5: Summary of Acid/Base Conditions and Compensation
      • Sources of Error in Blood Gas Analysis
        • Sources of Error in Blood Gas Analysis
      • Preexamination
        • Air Exposure
        • Delay in Testing
        • Others
        • True or False: Exposing an arterial blood gas sample to room air can cause a false elevation in the pCO2 level.
      • References
        • References

Additional Information

Level of Instruction: Basic
Intended Audience: Medical laboratory scientists and technicians, and other health care personnel who have an interest in this subject matter. This course is also appropriate for medical laboratory science students and pathology residents.
Author Information: Christine Wheary, MS, MLS(ASCP) has over 30 years of experience as a Medical Laboratory Scientist. She was the director of the MLS Program at UPMC Williamsport for eight and a half years. She was the sole didactic instructor and taught hematology, chemistry, immunohematology, microbiology, urinalysis, and immunology. She currently divides her working time as a generalist at UPMC Lock Haven and running her editing business.
Reviewer Information: Roger Beckering, M.Ed., BA (Chemistry), MLT(ASCP) has been an educator of medical laboratory sciences for over 25 years. He started as an instructor at the Medical Institute of Minnesota (MIM), later known as Argosy University. At Argosy, Roger held positions as Professor, Clinical Coordinator, and Program Director. In 2014, Roger moved to the Phoenix area where he works as a Professor and Administrator for MLT and MLS programs at Brookline College.