Ragavendra R. Baliga, M.D
Assistant Professor
Division of Cardiology
University Of Michigan

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Question 19 of 39:

In the CCU this patient should avoid activities such as toileting, assisted bathing and light ambulation, and prolonged bedrest (> 24 hours) is encouraged.

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A short period (~12 hours) of bed rest seems prudent for most patients with MI with allowances for bedside commode use. Prolonged bed rest is unnecessary except for patients with acute myocardial infarction who are hemodynamically unstable. Low-level activities such as toileting, assisted bathing and light ambulation should be used to prevent physiological deconditioning.

Limited early physical exertion and minimizing sympathetic stimulation (e.g, acute ischemic-type chest discomfort and anxiety) are methods of minimizing myocardial oxygen demand that increases the area of myocardial damage when coronary blood flow is limited [1]. In an earlier era the duration of bed rest was extended to several weeks until it was known that immobility is harmful because of the physiological deconditioning that occurs after even 6 hours in the supine position [2]. Preload decreases because of plasma volume losses that occur early in the bed rest period. Shifts in ventricular filling activate body's compensatory mechanisms to buffer pressure and volume alterations. Cardiovascular dysfunction after bed rest may be more a function of these fluid shifts than deconditioning from physical activity [3].

Reference:

1. Vatner SF, McRitchie RJ, Maroko PR, Patrick TA, Braunwald E. Effects of catecholamines, exercise and nitroglycerin on the normal ischemic myocardium in conscious dogs. J Clin Invest 1974;54:563-575.

2. Chobanian AV, Lille RD, Tercyak A, Blevins P. The metabolic and hemodynamic effects of prolonged bed rest in normal subjects. Circulation 1974;49:551-559.

3. Winslow EH. Cardiovascular consequences of bed rest. Heart Lung 1985;14:236-246.