Hypotension

A number of factors can cause hypotension (low blood pressure). Hypotension is considered less than 90/60 mm Hg in a normotensive adult. However, low blood pressure measurements are always interpreted in the context of a client’s baseline and past blood pressure readings as well as their current health state. Common symptoms associated with hypotension are lightheadedness, loss of consciousness, blurry vision, nausea, and fatigue.

Orthostatic Hypotension

Orthostatic hypotension is a specific type of hypotension that involves a drop in blood pressure associated with postural changes. Specifically, there is a drop in blood pressure when the client moves from lying to standing position (and sometimes from sitting to standing).

Have you ever stood up quickly and felt dizzy for a moment? This is because, blood is not getting to your brain so it is briefly deprived of oxygen. It can appropriate to assess for the presence of orthostatic hypotension when a client reports feeling dizzy, light-headed, or syncope when they sit up or stand up, or with a client who has been experiencing falls with no specific cause.

When a person moves from supine to standing, there is a gravitational pull in which a significant amount of blood moves from the core of the body to the periphery (e.g., the legs). Normally, there is a hemodynamic response which maintains venous return and cardiac output; this response involves a slight increase in the heart rate, constriction of the vasculature, and the maintenance of the blood pressure or a slight decrease. This hemodynamic response keeps the brain oxygenated so that cognitive and other neural processes are not interrupted. However, sometimes this response does not work properly.

If the sympathetic system cannot increase cardiac output, then blood pressure decreases, and a neurological loss can be felt. This can be brief, such as a slight dizziness when standing up too quickly, or could lead to a loss of balance, a fall, and neurological impairment for a period of time. The name for this is orthostatic hypotension, which means that blood pressure falls with postural changes from supine to standing. It can be the result of standing up faster than the reflex can occur, which may cause a benign ‘head rush,’ or it may be the result of an underlying cause.

There are several reasons why orthostatic hypotension occurs that can be cardiac or neurogenic related. For example, the blood volume may be too low and the sympathetic reflex is not effective. This hypovolemia may be the result of dehydration (related to factors such as severe diarrhea or vomiting) or medications that affect fluid balance, such as diuretics or vasodilators. The second underlying cause of orthostatic hypotension is autonomic failure. Several disorders can result in compromised sympathetic functions, ranging from diabetes to multiple system atrophy (a loss of control over many systems in the body), and addressing the underlying condition can improve the hypotension. Orthostatic hypotension is more common with advancing age and can be aggravated by antihypertensive medications.

How to Assess Orthostatic Hypotension

Orthostatic hypotension is assessed by measuring orthostatic or postural blood pressure and pulse changes. This procedure is done by assessing when the client moves from supine to sitting to standing and sometimes from supine to standing. There are variations in how this procedure is done in terms of position changes as well as timing (Arnold & Raj, 2017; Fedorowski et al., 2022; Kim & Farrell, 2022; Wieling et al., 2022). For example, blood pressure and pulse can be assessed immediately following position change to assess for initial orthostatic hypotension or at 3 minutes to assess for delayed orthostatic hypotension (Fedorowski et al., 2022). Because of the variations of assessment, you should document the approach (position changes) and the timing used. Here is a common way to proceed:

1. The client rests supine for five minutes.
2. Take blood pressure and pulse in supine position.
3. The client stands up.
4. Take blood pressure and pulse immediately (within 30 seconds) and then again at 3 minutes.

NOTE: if the client is severely symptomatic, you may add a sitting position between supine and standing. Alternatively, some practitioners use only sitting to standing due to convenience in primary care. In addition, some clients may be referred for a title table test.

How to Evaluate the Findings 

Normal variation is a 10 mm Hg decrease in blood pressure (systolic) from lying to standing and an increase in pulse of 10–15 bpm.

A decrease in blood pressure from lying to standing of systolic ≥ 20 mm Hg or diastolic ≥ 10 mm Hg is identified as orthostatic hypotension. An increase in pulse from lying to standing of ≥ 20 bpm is identified as orthostatic tachycardia.

References

Arnold, A. & Raj, S. (2017). Orthostatic hypotension: A practical approach to investigation and management. Canadian Journal of Cardiology, 33(12), 1725-1728.

Fedorowski, A. et al. (2022). Orthostatic hypotension: Management of a complex, but common, medical problem. Circulation: Arrhythmia and Electrophysiology, 15(3).

Kim, M. & Farrell, J. (2022). Orthostatic hypotension: A practical approach. American Family Physician, 105(1), 39-49.

Wieling, W. et al. (2022). Diagnosis and treatment of orthostatic hypotension. The Lancet Neurology, 21(8), 735-746.