Medical Information - Geriatric and healthcare of the elderly - Understanding Blood Pressure in the Elderly

Geriatric and healthcare of the elderly's series: Understanding Blood Pressure in the Elderly

BLOOD PRESSURE IN THE ELDERLY

 

More than half of all elderly people may have essential hypertension, which is not benign in this age group.  Their Cardiovascular morbidity and mortality rise more steeply with rising systolic pressure than in the middle aged.

 

Classification of Arterial Hypertension

	Pressure (mmHg)	Class
Systolic	< 140 140-159 >160	Normal Borderline isolated systolic hpt Isolated systolic hpt
Diastolic	<85 85-89 90-104 105-114 >115	Normal High normal Mild Moderate Severe

 

Classification	Systolic BP	Diastolic BP
Combined hpt	>160	>90
Borderline hpt	140-159	>90
Predominant systolic	> diastolic twice	>90
Isolated systolic hpt	>160	<90

 

BP measurement in the elderly is complicated by their increased variability of arterial pressure, but changes in the Korotkoff sounds, and by false low and high readings due to increased arterial stiffness.

 

Clinical evaluation

 

The principal diagnostic goals are:     

 

• to determine if the patient really has hypertension
• to search for secondary causes
• to assess end-organ damage to identify other risk factors for CV disease
• to assess comorbidity as older patients are more likely to have coexisting cardiac, vascular, and renal disease and are more likely to have different factors contributing to their hypertension.

 

History           

 

History of severe hypertension of sudden onset is particularly suggestive of renovascular (kidney-related) hypertension. 

 

Queries should be made about lifestyle factors, including diet, alcohol consumption, level of physical activity and smoking history. 

 

Drug Use

 

Some painkillers like NSAIDs may decrease the efficacy of several classes of antihypertensives.  Previously unsuccessful or poorly tolerated drugs need to be noted.

 

Type of Hypertension and BP occurrences common in the Elderly

 

i. White Coat Hypertension

 

This is an occurrence whereby the patient develops high BP in the consultation room of the doctor, but when BP is being measured at home for the rest of the day, it is normal.

 

ii. Pseudohypertension (increased blood pressure)

 

Arterial wall stiffness can interfere with blood pressure measurement.  A higher cuff pressure is needed to compress a hardened sclerotic artery than an elastic one, leading to discrepancies of up to 64 mmHg between cuff and intra arterial pressures. 

 

The Osler maneuver circumvents this by inflating the cuff above the systolic pressure and the radial/ brachial artery carefully palpated.  It is then determined if the patient is Osler positive or negative by the palpability of the pulse. 

 

This has important clinical consequences.  People misdiagnosed as having essential hypertension may be needlessly subjected to the inconvenience, cost, risk, and adverse effects of antihypertensive drugs. 

 

The elderly are particularly susceptible to adverse reactions of these drugs, which include transient ischemic episodes and fatal neurological events.

 

iii. Pseudohypotension (lowered blood pressure)

 

Localised atherosclerosis in some arteries may cause a drastic drop in pressure, so that it may be low in the arms yet be very high centrally. 

 

BP differences between the arms are common in the elderly, but high-grade occlusion in both arms are rare.  It is a possible consideration in patients with normal readings with excessive target organ disease, like high-grade retinopathy, LVH and renal failure.

 

iv. Korotkoff sound hiatus  

 

In patients with systolic hypertension the Korotkoff sounds may appear as the cuff pressure is lowered to about 220 mmHg, then disappear at around 190, to reappear at a much lower level, perhaps 140 and finally disappear at the true diastolic level of 90 mmHg. 

 

The cause of this hiatus is unknown.  To avoid spuriously low readings with elderly patients, the cuff must be inflated until the palpable arterial pulse disappears, and then be deflated very slowly.  This may cause a problem with automated equipment.

 

v. Nocturnal variation of BP

 

 

Systolic BP dropped by 14 to 16 mmHg (about 11%) and diastolic BP by 13 to 14 mmHg (about 17%). 

 

However, its measurement may not be accurate, as nocturnal measurement of BP has been found to disturb patient's sleep by up to 16 seconds, and therefore, could affect its result. 

 

This is important because some investigators believe that the failure of BP to fall during sleep may predict end-organ damage.

 

vi. Hypertension syndrome

 

Hypertension in the elderly may actually exist as a syndrome rather as a singular diagnosis. 

 

The syndrome comprises of:

 

• hypertension
• increased vascular diseases
• LV hypertrophy
• renal impairment
• insulin resistance
• obesity
• abnormal lipid profile.

 

Though it may exist as a cause and effect, there is evidence to show that they may all have common causes such as:

 

i. LVH- 50% of all hypertensive have increased LV mass.  LVH is an independent risk factor for CV events or deaths, and is associated with ventricular arrhythmia.

 

ii. Insulin resistance - 50% of untreated hypertensive has glucose intolerance due to resistance to glucose clearing action of insulin.

 

Hypertension, glucose intolerance and abnormal lipid profiles are individual risk for CV mortality and morbidity, and their effects together are more than additive.     

 

Hence, we have to ensure that treatment of one does not worsen the other e.g. of hypertension with diuretics will worsen lipid profile and glucose intolerance.

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