ABG Analysis, Easiest Steps

ABG Analysis Easy to Remember: 

Nurses often have difficulty interpreting arterial blood gases (ABGs). Confusion often begins with trying to remember many random rules and lacking a standardized. Approach to ABGs. In addition, nurses often attempt to analyze too many components. Of the ABG at the same time.The result is often confusion and an incorrect diagnosis.


Measurement of the dissolved oxygen and carbon dioxide in the arterial blood helps indicate the acid-base state and how well oxygen is being carried to the body.

Pre-procedure of ABG Analysis 

  • Perform Allen’s test before drawing radial artery specimens.
  • Have the client rest for 30 minutes before specimen collection to ensure accurate measurement of body oxygenation.
  • Do not turn off oxygen unless the ABG sample is prescribed to be drawn with the client breathing room air.

Collection of an arterial blood gas specimen

  • Obtain vital signs.
  • Determine whether the client has an arterial line in place.
  • Perform the Allen’s test to determine the presence of collateral circulation (see Priority Nursing Actions).
  • Assess factors that may affect the accuracy of the results, such as changes in theO2 settings, suctioning within the past 20minutes, and client’s activities.
  • Provide emotional support to the client.
  • Assist with the specimen draw by preparing a heparinized syringe.
  • Apply pressure immediately to the puncture site following the blood draw; maintain pressure for 5 minutes, or for 10 minutes if the client is taking anticoagulants.
  • Appropriately label the specimen and transport it on ice to the laboratory.
  • On the laboratory form, record the client’s temperature and the type of supplemental oxygen that the client is receiving.

Normal Arterial Blood Gas Values

PH: 7.35 to 7.45
PCO2: 35 to 45 mm Hg
HCO3: 22 to 27 mEq/L
PO2: 80 to 100 mm Hg
O2 saturation: 96% to 100%
Oxyhemoglobin dissociation curve: No shift

The 6 Easy Steps to ABG Analysis:

  • Is the pH normal?
  • I the CO2 normal?
  • Is the HCO3 normal?
  • Match the CO2 or the HCO3 with the pH
  • Does the CO2 or the HCO3 go the opposite direction of thepH?
  • Are the pO2 and the O saturation normal?

Post- procedure

  • Place the specimen on ice.
  • Note the client’s temperature on the laboratory form.
  • Note the oxygen and type of ventilation that the client is receiving on the laboratory form.
  • Apply pressure to the puncture site for 5 to 10 minutes or longer if the client is receiving anticoagulant therapy or has a bleeding disorder.
  • Transport the specimen to the laboratory within 15 minutes.
  • See Chapter 10 for discussion of the analysis of ABG results.

Steps for analyzing Arterial Blood Gas results

If you can remember the following Pyramid Points and Pyramid Steps, you will be able to analyze any blood gas report.

Pyramid Points

In acidosis, the pH is decreased.

In alkalosis, the pH is elevated.

The respiratory function indicator is the PCO2.

The metabolic function indicator is the bicarbonate ion (HCO3

Pyramid Steps

Pyramid Step 1

Look at the blood gas report. Look at the pH. Is the pH elevated or decreased? If the pH is elevated, it reflects alkalosis. If the pH is decreased, it reflects acidosis.

Pyramid Step 2

Look at the PCO2. Is the PCO2 elevated or decreased? If the PCO2 reflects an opposite relationship to the pH, then the condition is a respiratory imbalance. If the PCO2 does not reflect an opposite relationship to the pH, go to Pyramid Step 3.

Pyramid Step 3

Look at the HCO3

Does the HCO3 reflect acorresponding relationship with the pH? If it does, then the condition is a metabolic imbalance.

Pyramid Step 4

Compensation has occurred if the pH is in a normal range of 7.35 to 7.45. If the pH is not within normal range, look at the respiratory or metabolic function indicators. If the condition is a respiratory imbalance, look at the HCO3 to determine the state of compensation. If the condition is a metabolic imbalance, look at the PCO2 to determine the state of compensation.



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