effect of prone positioning on cardiac function

Q: What is the effect of prone positioning on cardiac function? (select one)

A) Increase in cardiac output

B) Decrease in cardiac output

Answer: A

 Assuming, a patient has a relatively stable cardiac function, prone position increase the cardiac output contrary to believe that sternal pressure of chest wall on the heart will decrease cardiac output. This occurs due to two mechanisms 

 1. Decrease pressure of heart on the lungs leading to increased lung recruitment, which results in increase right ventricular preload and decrease right ventricular afterload 

2. Reduction in hypoxic pulmonary vasoconstriction leading to a decrease in pulmonary vascular resistance


#pulmonary
#cardiology


References:

1. Albert RK, Hubmayr RD. The prone position eliminates compression of the lungs by the heart. Am J Respir Crit Care Med 2000; 161:1660.

2. Jozwiak M, Teboul JL, Anguel N, et al. Beneficial hemodynamic effects of prone positioning in patients with acute respiratory distress syndrome. Am J Respir Crit Care Med 2013; 188:1428.

3. Malbouisson LM, Busch CJ, Puybasset L, et al. Role of the heart in the loss of aeration characterizing lower lobes in acute respiratory distress syndrome. CT Scan ARDS Study Group. Am J Respir Crit Care Med 2000; 161:2005.