CVP Physiological and Pathophysiological Concepts 3

Question 1

During CPB, a patient with a known left ventricular aneurysm is at greatest risk for which perfusion-related complication?

Accepted Answer

Inadequate LV venting leading to ventricular distension

Answer

Paradoxical air embolism through the aneurysm wall

Answer

Spontaneous coronary artery dissection

Answer

Aortic root over-pressurization

Question 2

The oxygen-hemoglobin dissociation curve shifts to the right in the presence of:

Accepted Answer

Acidosis, hyperthermia, and elevated 2,3-DPG

Answer

Alkalosis and hypothermia

Answer

Low CO2 partial pressure

Answer

Fetal hemoglobin

Question 3

Which pathophysiologic mechanism underlies the phenomenon of 'coronary steal' in patients with coronary artery disease during CPB?

Accepted Answer

Vasodilators preferentially dilate non-stenotic vessels, diverting flow from ischemic territories

Answer

Hypothermia causes coronary vasospasm in diseased segments

Answer

Hemodilution reduces oxygen-carrying capacity beyond compensatory limits

Answer

Elevated perfusion pressure forces flow into non-ischemic regions

Question 4

In the context of cardiopulmonary bypass, which statement about the systemic inflammatory response syndrome (SIRS) is most accurate?

Accepted Answer

Contact of blood with the CPB circuit activates complement, cytokines, and neutrophils

Answer

SIRS is caused exclusively by protamine administration

Answer

Hypothermia abolishes the inflammatory response during CPB

Answer

SIRS only occurs in pediatric patients on CPB

Question 5

A patient's arterial blood gas on CPB shows pH 7.30, PaCO2 55 mmHg, PaO2 320 mmHg. The perfusionist should first:

Accepted Answer

Increase sweep gas flow rate to remove excess CO2

Answer

Decrease the oxygenator FiO2 to reduce PaO2

Answer

Add sodium bicarbonate to correct the acidosis

Answer

Reduce pump flow to lower metabolic CO2 production

Question 6

Which aspect of myocardial oxygen consumption (MVO2) is most significantly reduced by cardioplegic arrest?

Accepted Answer

Electromechanical activity

Answer

Basal cellular metabolism

Answer

Wall stress component from pressure work

Answer

Fatty acid oxidation substrate utilization

Question 7

During reperfusion after global myocardial ischemia, calcium overload of myocytes is primarily mediated by:

Accepted Answer

Reversal of the sodium-calcium exchanger due to intracellular sodium accumulation

Answer

Direct membrane rupture from ischemic injury

Answer

Increased L-type calcium channel expression

Answer

Mitochondrial calcium release triggered by ATP restoration