Bilateral Indirect and Direct Arterial Pressures

Abstract

Bilateral determinations of the blood pressures were made nonsimultaneously and simultaneously by the indirect method under basal conditions on 447 patients. In this group 26.6 per cent of the paired measurements by the nonsimultaneous indirect method exhibited systolic differences of 10 mm. Hg or greater and 15 per cent exhibited diastolic differences of this magnitude, whereas only 5.3 per cent of the measurements by the simultaneous indirect method had systolic differences and only 4 per cent had diastolic differences of this degree. This indicates that bilateral determinations of blood pressure must be performed simultaneously on patients being examined for possible inequalities of blood pressure. Bilateral differences in blood pressure obtained by the simultaneous indirect and simultaneous direct methods in 14 normal subjects and 53 selected patients were compared. In the normal subjects, 3 of the 42 paired indirect measurements and none of the paired direct measurements in either the radial or brachial arteries had systolic differences of 10 mm. Hg or greater, and none of the diastolic differences were of this level. In the 53 selected patients, 10 per cent of the indirect and 6 per cent of the direct measurements of systolic blood pressure differed by 10 mm. Hg or more and 8 per cent of the paired indirect measurements of diastolic blood pressure and less than 1 per cent of the paired direct measurements differed by this amount. These differences in bilateral blood pressures were characterized by their inconstancy and lack of agreement with subsequent measurements when studied by both the indirect and direct methods, which apparently separates them from those due to altered hemodynamics from pathologic conditions of the aortic arch or its tributaries. Bilateral differences of blood pressure are of clinical importance when they are great and are reproducible by the direct as well as by the indirect methods, as illustrated by a patient encountered in this study. In addition, 1 case of extreme obesity and 1 of advanced arteriosclerosis were reported. Both patients were found to have pseudohypertension, which was detected in this study. A slight increase in the incidence of bilateral differences in indirect blood pressures was found in a group of patients whose blood pressures were measured while they were in the supine and then in the sitting position. A slight increase in the incidence of bilateral differences was found at higher levels of blood pressure by comparing the blood pressures of nonhypertensive and hypertensive patients and of hypertensive patients before and during treatment with antihypertensive drugs. Bilateral inequalities of blood pressure did not appear to be related to the age or sex of the subjects. Likewise, differences in circumferences of the arm or right or left-handedness did not appear to influence these inequalities, and there was no marked side dominance for differences found. Bilaterally simultaneous, indirect measurements of blood pressure should be carried out on patients with hypertension who will be treated with antihypertensive drugs. Bilateral direct measurements may be used to verify the existence of inequality of blood pressures detected by the indirect method and to determine the correct pressure to be followed. This is particularly important in patients being screened for pheochromocytomas, since such differences may produce false-positive results.

The interarm blood pressure difference as predictor of cardiovascular events in patients with hypertension in primary care: cohort study

“…Although our prevalence figures of 23% with a sIAD X10 mm Hg and 6% with a dIAD X10 mm Hg are lower than the figures that we and others have reported previously from primary care, 3,7,15,16 they are close to the best estimates we have calculated from the most methodologically robust studies. 4 We had anticipated a higher prevalence of the IAD than we reported previously, as it has been shown to occur more frequently in hypertensive than normotensive populations in selective studies, 4,[17][18][19] but no previous series of hypertensive patients reported from primary care was available to support this contention. The final prevalence figures were lower than those in our interim report 3 on this cohort, but we have previously shown that prevalence will fall with repeated pairs of measurements.…”

Is the blood pressure the same in both arms?

“…Of the 447 patients studied by Harrison et al (1960) with nonsimultaneous measurements, 27 % had systolic differences and 15 % had diastolic differences in excess of 10 mmHg for individual recordings. When the indirect readings were made simultaneously the respective percentages were 5 % for systolic and 4 % for diastolic pressures.…”

“…It is not suprising, therefore, to find wide interarm differences in single indirect readings, although these are greatly diminished by taking the average of several readings. Even if great care is taken to ensure that exactly the same technique is followed for each measurement, that comparative measurements are made simultaneously with cuffs of the same dimensions, and that the instruments used are accurate and give the same readings when checked against each other, variable differences will be found (Allen and Hines 1939;Harrison et al, 1960). …”

Inter-arm blood pressure difference and mortality: a cohort study in an asymptomatic primary care population at elevated cardiovascular risk

“…[36][37][38][39][40][41] Studies looking specifically at left or right handedness have also failed to demonstrate an association with the higher-reading arm. 33,42 In the current study, blood pressures were recorded in a fixed sequence for anklebrachial index assessment, 18 which may account for the bias towards higher rightarm blood pressures observed through order effects.…”