Blood Pressure and Dizziness –Part II

Alan Desmond
April 12, 2011

Last week we talked about blood pressure and dizziness, and a condition known as orthostatic hypotension. This week we dig a bit deeper, and talk about proper measurement techniques as well as problems with diagnosing this condition.
Orthostatic hypotension is a clinical sign, not a disease. The most common symptom associated with OH is postural pre-syncope (a lightheaded or near faint sensation), frequently noted when rising from the sitting or supine position. Other symptoms may include vague dizziness, loss of balance and visual disturbance (all due to insufficient blood flow to the brain). The symptoms are typically worse when standing and improve with lying down. Some patients may even describe the sensation as vertigo. When given a forced choice (e.g. Is it more like spinning, or more like feeling faint?) most will choose “feeling faint.”
Typical complaints of OH include:
“I get dizzy and off balance when I stand up.”
“I get up and start to walk and feel like I am going to fall over.”
“When I get up quickly, I feel like I could faint.”
The American Academy of Neurology (1996) has issued a consensus statement defining orthostatic hypotension:
“Orthostatic hypotension (OH) is a reduction of systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at least 10 mm Hg within three minutes of standing. It is a physical sign and not a disease. An acceptable alternative to standing is the demonstration of a similar drop in blood pressure within three minutes, using a tilt table in the head up position, at an angle of at least 60 degrees. Confounding variables to be considered when reaching a diagnosis should include: food ingestion, time of day, state of hydration, ambient temperature, recent recumbency, postural deconditioning, hypertension, medications, gender, and age. Orthostatic hypotension may be symptomatic or asymptomatic. Symptoms of OH are those that develop on assuming the erect posture or following head-up tilt and usually resolve on resuming the recumbent position. They may include lightheadedness, dizziness, blurred vision, weakness, fatigue, cognitive impairment, nausea, palpitations, tremulousness, headache and neck ache. If the patient has symptoms suggestive of, but does not have documented, orthostatic hypotension, repeated measurements of blood pressure should be performed. Occasional patients may not manifest significant falls in blood pressure until they stand for at least ten minutes.” (American Academy of Neurology, 1996).

There is some inconsistency in both education and practice regarding measurement techniques for orthostatic hypotension. Orthostatic hypotension can be evaluated by having the patient lie down for 5 to 10 minutes and then checking blood pressure while still in the supine position. The examiner then asks the patient to stand up quickly, and rechecks the blood pressure immediately and again after about 1 and 3 minutes. If the patient has a history of postural pre-syncope, and no decrease in BP is noted, it is advisable to have the patient remain standing and recheck BP at intervals over a ten minute period. Improper technique can result in failure to identify significant drops in blood pressure. It is recommended that the patient be brought directly from supine to standing, skipping a measurement in the sitting position. Even with proper technique, positive findings in measurement for orthostatic hypotension suffer from poor reproducibility. Vara-Gonzalez et al. (2006) report that “reproducibility of postural changes of BP in hypertensive elderly patients in a primary care setting is low. Thus, the assessment of postural hypotension should be based on repeated measurements taken on several occasions.” In my practice we have patients perform self-monitoring of blood pressure on a home basis. This allows repeated measurement at different times of day, over several days. Home blood pressure measurements have been found to be generally reliable in most patients. Home measurement devices used on the wrist or finger have been found to be less reliable than a traditional arm worn monitors. A more sensitive and sophisticated measure for orthostatic hypotension (and other orthostatic symptoms) is a tilt table test.

NOTE: Although orthostatic hypotension is commonly seen in a balance clinic, the diagnosis and treatment of this condition is within the scope of a medical doctor, not a doctor of audiology. We work closely with our medical doctor colleagues in evaluating this complaint, but always refer back to the primary care physician for management.
Reproducibility of postural changes of blood pressure in hypertensive elderly patients in primary care.Vara-González L et al. Blood Press Monit. (2006)

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