A patient on bed rest exhibits orthostatic hypotension upon standing. This would MOST likely be characterized by

A patient on bed rest exhibits orthostatic hypotension upon standing. This would MOST likely be characterized by

• A. increased venous tone in the lower extremity
• B. inadequate ventricular filling during diastole
• C. decrease hydrostatic pressure in the capillary beds
• D. parasympathetic stimulation of the heart

Answer: (B)

Orthostatic hypotension after prolonged bed rest is explained by reduced venous return when standing, which lowers how much blood fills the ventricles during diastole. With less filling, the end-diastolic volume (preload) drops, leading to a smaller stroke volume and a fall in blood pressure as you stand. So the scenario is best described by inadequate ventricular filling during diastole. Increased venous tone would help return blood to the heart and reduce pooling, not cause this drop. Decreased hydrostatic pressure in capillary beds isn’t the mechanism behind standing-induced hypotension. Parasympathetic stimulation of the heart would slow the heart rate, but the primary issue here is insufficient venous return/preload rather than reflex bradycardia.

Orthostatic hypotension after prolonged bed rest is explained by reduced venous return when standing, which lowers how much blood fills the ventricles during diastole. With less filling, the end-diastolic volume (preload) drops, leading to a smaller stroke volume and a fall in blood pressure as you stand. So the scenario is best described by inadequate ventricular filling during diastole.

Increased venous tone would help return blood to the heart and reduce pooling, not cause this drop. Decreased hydrostatic pressure in capillary beds isn’t the mechanism behind standing-induced hypotension. Parasympathetic stimulation of the heart would slow the heart rate, but the primary issue here is insufficient venous return/preload rather than reflex bradycardia.