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(Hypertension. 1995;26:383-389.)
© 1995 American Heart Association, Inc.
Articles |
Isolated Elevation of Diastolic Blood Pressure
Real or Artifactual?
From the Cardiovascular Center, The New York Hospital–Cornell University Medical Center, New York, NY (S.G.B., S.J.M., G.D.J., T.G.P.); Department of Electromechanical Engineering Technology, New York City Technical College/CUNY, Brooklyn, NY (S.G.B.); and Acoustic Research Department, AT&T Bell Laboratories, Murray Hill, NJ (J.E.W.).
Correspondence to Seymour G. Blank, PhD, Department of Electromechanical Engineering Technology, New York City Technical College, 186 Jay St, Room V633, Brooklyn, NY 11201.
Abstract Not infrequently, blood pressure measurement by the
standard auscultatory technique yields a normal systolic pressure with
an elevated diastolic pressure. The relatively narrow pulse
pressure of such a measurement raises concern about the accuracy of the
blood pressure measurement. The purpose of this study was to assess the
accuracy of auscultatory blood pressure measurements in patients with
an uncommonly narrow pulse pressure, particularly patients with an
elevated diastolic but normal systolic pressure.
Auscultatory blood pressure measurements were compared with an
objective noninvasive standard, called K2 analysis, which has
been shown to be more accurate than the auscultatory technique.
Blood pressure was measured simultaneously by auscultatory
and K2 techniques in 175 subjects. Comparisons were performed (1)
in the group as a whole, (2) in four clinical subgroups (normotensive
[<140/<90 mm Hg, n=69], hypertensive [
140/90 mm Hg, n=53],
isolated systolic hypertensive [140/<90 mm Hg, n=38], and
isolated diastolic hypertensive [<140/90 mm Hg,
n=15]), and (3) in two subgroups whose ratio of pulse pressure to
diastolic pressure was greater than or equal to 0.45
(n=151) or less than 0.45 (n=24). Subjects in the isolated
diastolic hypertensive group and in the group with a pulse
pressure ratio less than 0.45 were considered to have a narrow pulse
pressure. In the group as a whole, consistent with previous
auscultatory-K2 comparisons, systolic pressure was slightly higher and
diastolic pressure slightly lower when measured by K2
versus the auscultatory technique (auscultatory, 145/85 mm Hg; K2,
147/83 mm Hg). For diastolic pressure auscultatory
measurements averaged 7 mm Hg greater than K2 in the isolated
diastolic hypertensive group (94±4 versus 87±5 mm Hg)
but were less than 3 mm Hg (greater) in the other three groups
(P<.0004). For systolic pressure, differences were less
than 3 mm Hg in all four clinical groups. Auscultatory-K2 differences
of diastolic pressure exceeding 5 mm Hg (and 10 mm Hg)
were seen in 73.3% (and 40.0%) of isolated diastolic
hypertensive subjects versus only 14.5% (2.9%) of normotensive
subjects, 22.6% (1.9%) of hypertensive subjects, and 7.9% (2.6%) of
isolated systolic hypertensive subjects (P<.0001).
Similarly, the auscultated diastolic pressure exceeded the
K2 measurement by at least 5 mm Hg (and 10 mm Hg) in 62.5% (29.2%)
of subjects with a pulse pressure ratio less than 0.45 versus 13.9%
(2.0%) in subjects with a ratio greater than or equal to 0.45
(P<.0001). Auscultatory-K2 differences of
diastolic pressure were strongly and inversely related to
the pulse pressure ratio (r=-.68, P<.0001)
independent of sex, race, or body weight. In conclusion, when the pulse
pressure is particularly narrow, auscultation frequently overestimates
the true diastolic pressure by 5 mm Hg or more. The
treatment implications of this finding, particularly in patients with
elevated diastolic but normal systolic pressure, merit
further study.
Key Words: pseudohypertension • blood pressure determination
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