Orthostatic, or postural, vital signs are used to evaluate the body’s response to position changes when volume loss is suspected. Under normal conditions blood pooling in the lower extremities during
position change is directed back to the upper body through the vasoconstriction of blood vessels
(Winslow, Lane, & Woods, 1995). However, conditions leading to hypovolemia and autonomic failure
may result in a sudden drop in blood pressure known as orthostatic hypotension (OH) and result in
impaired perfusion to the upper body. The American Autonomic Society and the American Academy of
Neurology define OH as a 20 mmHg or greater decrease in systolic blood pressure (SBP) and a 10 mmHg
or greater decrease in diastolic blood pressure (DBP) within three minutes of standing (American
Academy of Neurology, 1996). This drop in blood pressure may be associated with symptoms such as
lightheadedness, dizziness, blurred vision, weakness, fatigue, cognitive impairment, nausea,
palpitations, tremulousness, headache, neck ache and syncope (American Academy Neurology, 1996;
Cooke et al., 2009; Koziol-McLain, Lowenstein, & Fuller, 1991; Naschitz, & Rosner, 2007; Sarasin et al.,
2002).
