CCP Blood Gas & Acid-Base Interpretation 2

Question 1

A patient on CPB has a PaCO2 of 35 mmHg at 37°C (alpha-stat). If body temperature is actually 28°C, what is the temperature-corrected PaCO2?

Accepted Answer

Approximately 24 mmHg

Answer

CO2 solubility increases with cooling, so temperature-corrected PaCO2 is lower (~24 mmHg) than the 37°C measurement in alpha-stat management.

Question 2

Which buffer system provides the most immediate response to an acute acid load in the blood?

Accepted Answer

Bicarbonate-carbonic acid system

Answer

The bicarbonate-carbonic acid system is the most important extracellular buffer and responds immediately to acute acid loads due to its open system with pulmonary CO2 elimination.

Question 3

A blood gas shows pH 7.52, PaCO2 28 mmHg, HCO3- 22 mEq/L. What is the primary disorder?

Accepted Answer

Respiratory alkalosis uncompensated

Answer

Low PaCO2 with high pH and near-normal HCO3- indicates uncompensated respiratory alkalosis; compensation would have lowered bicarbonate further.

Question 4

During hypothermic CPB at 20°C using pH-stat management, the perfusionist adds CO2 to the oxygenator. What is the primary intended effect?

Accepted Answer

Maintain temperature-corrected pH at 7.40 and PaCO2 at 40 mmHg

Answer

pH-stat management adds CO2 to correct for hypothermia-induced alkalosis, maintaining temperature-corrected pH 7.40 and PaCO2 40 mmHg.

Question 5

In a patient with chronic COPD, a blood gas shows pH 7.36, PaCO2 60 mmHg, HCO3- 33 mEq/L. This represents:

Accepted Answer

Chronic respiratory acidosis with full metabolic compensation

Answer

Elevated PaCO2 with proportionally elevated HCO3- and near-normal pH indicates chronic respiratory acidosis with full renal compensation.

(CCP) Certified Clinical Perfusionist Practice Test

(CCP) Certified Clinical Perfusionist Practice Test

CCP Blood Gas & Acid-Base Interpretation 2