Postural hypotension: symptoms and management

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Postural hypotension:

is defined as a reduction in systolic blood pressure of 20mmHg or more after standing for at least one minute (Miller, 1999). Also known as orthostatic hypotension, it is a common problem in older people, affecting 10-33% of them (Harris et al, 1991; Patel et al, 1993).

VOL: 97, ISSUE: 03, PAGE NO: 39
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Phil Jevon, BSc, PGCE, RN, is a resuscitation officer, Walsall Hospitals NHS Trust

The prevalence of postural hypotension increases with age and it arises as a complication of a number of diseases, for example diabetes. It can present with clinical symptoms of dizziness, syncope and falls when the patient changes position.

Although it may seem to be a relatively harmless phenomenon, patients’ safety and quality of life can be seriously affected. An understanding of the causes, together with appropriate nursing management, is essential.

Maintaining blood pressure

The body needs to maintain blood pressure to ensure adequate perfusion of organs, particularly when an organ’s functional demands increase. This relies on the integrity of the heart and blood vessels, maintenance of intravascular volume and various circulating and local vasoactive agents (Mathias and Kimber, 1999).

Blood pressure is regulated in part by baroreceptors, which are located in the aortic arch, carotid arteries and carotid sinus. By influencing the heart rate and peripheral vascular resistance via the autonomic nervous system, these help to compensate for transient changes in arterial pressure, maintaining it at a constant level.

Age-related changes in the baroreflex mechanisms can precipitate postural hypotension. The baroreflex-mediated heart rate response to both hypotensive and hypertensive stimuli can become impaired.

In addition, blood pressure regulation can be affected by age-related and disease-related cardiovascular changes, such as atherosclerosis. Arterioles are less able to constrict in response to rapid changes in position, for example when standing up, which makes older people more susceptible to postural hypotension (Andresen, 1998; Miller, 1999).

Causes and risk factors:

Although the condition can occur in healthy older people, it is more common in those who have additional risk factors (Miller, 1999). It particularly affects people on prolonged bedrest and those aged over 74. However, it is not confined to the older population.

It can be caused by:

* Hypovolaemia;
* Diabetes;
* Peripheral neuropathy;
* Parkinson’s disease;
* Anaemia;
* Adrenal insufficiency.

There are also a number of drugs that can cause postural hypotension (Box 1).

Clinical features and diagnosis

The clinical features of postural hypotension relate to the degree of the fall in blood pressure and hypoperfusion of the brain and other organs.

The symptoms may vary from dizziness to syncope, which are both associated with visual disturbances ranging from blurred vision to blackouts (Mathias, 1995).

Other possible manifestations include weakness, angina, low backache and lethargy (Bleasdale-Barr and Mathias, 1998). Sometimes the patient may not have any symptoms.

One of the most common complaints older patients present with is a history of falls. Other symptoms include confusion and continence problems.

Diagnosis of postural hypotension involves demonstrating a postural fall in blood pressure after standing. The patient’s lying and standing blood pressure measurements should be taken, preferably in the morning (See Practical procedures, p41).

In a patient who has unexplained syncope and falls, the symptoms need to be reproduced to make a diagnosis. Assessing for the presence of postural hypotension is particularly relevant in older people with a history of falls (Jordan and Torrance, 1995).

Further investigation in a dedicated laboratory using a tilt table may also be necessary to ensure that patients with profound postural hypotension or with associated neurological disabilities can be returned to a horizontal position rapidly and safely (Mathias and Kimber, 1999).

Non-invasive 24-hour blood pressure monitoring may determine whether the patient has hypotension when standing and night-time hypertension when lying down. After eating a meal, the patient may experience a significant fall in blood pressure that may be a symptom of the condition. Again, this can only be diagnosed by measuring the patient’s standing blood pressure after a meal (O’Brien et al, 1995).

Nursing management and lifestyle advice

For patients with symptomatic postural hypotension, it is important to alleviate the symptoms and prevent them from recurring so as to minimise the risk of injury and maintain the patient’s quality of life. Key aspects of the nursing management of a patient with postural hypotension are described in Box 2.

It is of primary importance to provide patient education before discharge. Advice to the patient should include, for example, taking care when changing from a sitting to a standing position and when taking medication that could precipitate postural hypotension (Box 3).

Medical management:

In patients with chronic postural hypotension the aim is to ensure appropriate mobility and function, prevent falls and provide low-risk treatment while maintaining a suitable quality of life (Mathias and Kimber, 1999). If possible, the cause should be treated.

When non-pharmacological treatment measures are not wholly successful, drugs that help to raise the blood pressure may be considered: for example, although fludrocortisone is not licensed for the treatment of postural hypotension it is usually the drug of choice (Mathias and Kimber, 1999). Its actions include volume expansion and the promotion of arteriole vasoconstriction.

Conclusion

Postural hypotension is a common condition in older people. The lying and standing blood pressure measurements of all older patients should ideally be taken routinely. If they are taking hypotensive-inducing medication it is essential to monitor their lying and standing blood pressure (Mader, 1989).

Nurses have a key role in monitoring, maintaining and promoting a safe environment and providing lifestyle advice for patients with postural hypotension.
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