CVP Physiological and Pathophysiological Concepts 4

Question 1

Which hemodynamic parameter best reflects left ventricular preload in a patient on cardiopulmonary bypass?

Accepted Answer

Left ventricular end-diastolic volume (LVEDV)

Answer

LVEDV most directly reflects left ventricular preload, as volume (not pressure) is the true determinant of myocardial fiber length per the Frank-Starling mechanism.

Question 2

During hypothermic CPB at 28°C, the perfusionist notes a significant decrease in pump flow requirement to maintain adequate MAP. This is primarily due to:

Accepted Answer

Reduced oxygen consumption decreasing the required cardiac output

Answer

Hypothermia reduces metabolic rate and oxygen consumption, allowing lower pump flows to meet the body's reduced oxygen demand.

Question 3

In a patient with a pre-existing right-to-left intracardiac shunt, which CPB management consideration is most critical?

Accepted Answer

Vigilant air removal from the venous side of the circuit to prevent paradoxical embolism

Answer

In right-to-left shunts, venous air can bypass the pulmonary filter and cause paradoxical systemic arterial air embolism.

Question 4

The LaPlace relationship (wall stress = pressure × radius / 2 × wall thickness) predicts that in dilated cardiomyopathy, myocardial oxygen demand is increased because:

Accepted Answer

Increased radius raises wall stress despite normal or low pressure

Answer

Ventricular dilation increases the radius term in LaPlace's law, raising wall stress and thus myocardial oxygen consumption even at normal pressures.

Question 5

Hyperosmolar cardioplegia solutions reduce myocardial edema during ischemia primarily by:

Accepted Answer

Creating an osmotic gradient that draws water out of myocytes

Answer

The hyperosmolar extracellular environment creates an osmotic gradient drawing water from myocytes into the interstitium, reducing cellular edema.

(CVP) Cardiovascular Perfusionist Practice Test

(CVP) Cardiovascular Perfusionist Practice Test

CVP Physiological and Pathophysiological Concepts 4