Cardiopulmonary Physiology & Pathophysiology Flashcards

Which mechanism explains why patients with longstanding mitral stenosis develop pulmonary arterial hypertension?

Answer: Direct transmission of elevated left atrial pressure causing reactive pulmonary vasoconstriction and remodeling

Chronic elevation of left atrial pressure in mitral stenosis is transmitted backward, causing reactive pulmonary vasoconstriction and eventual vascular remodeling.

What is the significance of coronary autoregulation in the context of cardiopulmonary bypass management?

Answer: Autoregulation maintains constant coronary flow over a mean pressure range of approximately 50-150 mmHg

Coronary autoregulation maintains relatively constant blood flow over a mean arterial pressure range of approximately 50-150 mmHg through arteriolar tone adjustment.

During separation from bypass, the perfusionist notices the patient develops severe bronchospasm and hypotension after protamine administration. What is the most likely underlying mechanism?

Answer: Anaphylactic or anaphylactoid reaction causing massive histamine and complement activation

Protamine reactions include anaphylactic responses (especially in patients with fish or insulin allergies) causing histamine release, complement activation, bronchospasm, and cardiovascular collapse.

Which parameter best reflects global oxygen balance and would alert the perfusionist to impending tissue hypoxia during bypass?

Answer: Mixed venous oxygen saturation (SvO2) from the venous reservoir

Mixed venous oxygen saturation reflects the balance between oxygen delivery and consumption globally, falling when tissues are extracting excess oxygen due to inadequate delivery.

In the pathophysiology of right heart failure following cardiac surgery, which sequence of events is most accurate?

Answer: Right ventricular dilation → tricuspid regurgitation → decreased LV filling → reduced cardiac output

RV failure causes dilation, which displaces the interventricular septum and causes functional TR, reducing LV filling through ventricular interdependence and ultimately lowering cardiac output.

A perfusionist is managing a patient with severe chronic anemia (Hgb 6 g/dL) pre-operatively. Which compensatory mechanism would be expected BEFORE bypass?

Answer: Increased cardiac output and heart rate to maintain oxygen delivery

Chronic anemia triggers compensatory increases in cardiac output and heart rate to maintain adequate oxygen delivery despite reduced oxygen-carrying capacity.

Which statement correctly describes the relationship between cardiac output and oxygen delivery (DO2) during normothermic cardiopulmonary bypass?

Answer: DO2 equals cardiac output multiplied by arterial oxygen content (CaO2)

Oxygen delivery (DO2) is the product of cardiac output (pump flow during bypass) and arterial oxygen content (CaO2 = Hgb × 1.34 × SaO2 + 0.003 × PaO2).