Cardiopulmonary Physiology & Pathophysiology Flashcards

A perfusionist observes that systemic vascular resistance is markedly elevated during rewarming from hypothermic bypass. What is the most appropriate initial intervention?

Answer: Administer a vasodilator such as sodium nitroprusside or nicardipine

Elevated SVR during rewarming is best managed with vasodilators to reduce afterload, improve flow distribution, and facilitate even rewarming.

Which physiologic parameter is most directly measured by a pulmonary artery catheter to assess right ventricular function?

Answer: Pulmonary artery systolic pressure reflecting right ventricular systolic pressure

Pulmonary artery systolic pressure measured by the PA catheter directly reflects right ventricular systolic pressure (in the absence of pulmonic stenosis).

Which condition is characterized by decreased lung compliance, increased work of breathing, and bilateral infiltrates following transfusion?

Answer: Transfusion-related acute lung injury (TRALI)

TRALI is characterized by non-cardiogenic pulmonary edema with bilateral infiltrates, hypoxemia, and decreased compliance occurring within 6 hours of transfusion.

How does hypothermia affect the oxyhemoglobin dissociation curve and oxygen delivery during bypass?

Answer: Hypothermia shifts the curve left, reducing O2 release but also reducing metabolic demand

Hypothermia shifts the oxyhemoglobin dissociation curve leftward (increased hemoglobin-O2 affinity), but this is offset by reduced metabolic oxygen demand at lower temperatures.

What is the primary pathophysiologic mechanism in aortic stenosis that eventually leads to left ventricular failure?

Answer: Pressure overload causing concentric hypertrophy and diastolic dysfunction

Aortic stenosis causes chronic pressure overload, leading to concentric LV hypertrophy, diastolic dysfunction, and eventually systolic failure.

During weaning from cardiopulmonary bypass, which finding would most likely indicate inadequate coronary perfusion?

Answer: ST segment elevation on the ECG with new regional wall motion abnormality

ST elevation with new regional wall motion abnormality indicates myocardial ischemia, suggesting inadequate coronary perfusion during or after bypass.

A patient with a history of congestive heart failure has a cardiac index of 1.6 L/min/m² during pre-bypass assessment. According to Fick's principle, if VO2 is 200 mL/min/m² and Hgb is 10 g/dL with SaO2 99%, what does this suggest about mixed venous saturation?

Answer: SvO2 would be approximately 55-60%, indicating high oxygen extraction

With a low cardiac index and normal VO2, tissues must extract a greater fraction of delivered oxygen, resulting in a low SvO2 of approximately 55-60%.