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Are Aneroid Sphygmomanometers Accurate in Hospital and Clinic Settings?
Vincent J. Canzanello, MD;
Patricia L. Jensen, RN;
Gary L. Schwartz, MD
Arch Intern Med. 2001;161:729-731.
Background The aneroid sphygmomanometer is commonly used for the indirect measurement
of blood pressure despite significant concerns about its accuracy. Although
the mercury sphygmomanometer is highly accurate, there are concerns about
the environmental toxicity of mercury. In response to various external pressures
to become essentially mercury free, the Mayo Clinic, Rochester, Minn, has
replaced many mercury sphygmomanometers with aneroid devices. Since 1993,
a maintenance protocol has been in place to ensure proper function and accuracy
of these devices.
Methods We assessed the accuracy of 283 aneroid devices using as the reference
standard a digital pressure and vacuum meter that was calibrated using a mercury
sphygmomanometer.
Results The mean ± SD values from the aneroid device in millimeters of
mercury at each reference point (at 20–mm Hg intervals from 60 to 240
mm Hg defined by the reference device) were 59.9 ± 1.9 at 60; 79.9
± 1.9 at 80; 100.0 ± 1.8 at 100; 120.3 ± 1.8 at 120;
140.7 ± 1.4 at 140; 160.7 ± 1.7 at 160; 180.9 ± 1.3 at
180; 200.7 ± 5.0 at 200; 221.0 ± 1.3 at 220; and 240.8 ±
1.6 at 240 (r = 0.99; P<.001).
The values from the aneroid device underestimated those of the reference device
by a mean of 0.5 mm Hg (95% confidence interval, 0.3-0.7). Virtually 100%
of the values from the aneroid device were within the 4–mm Hg range
recommended by the Association for the Advancement of Medical Instrumentation.
Conclusion Aneroid sphygmomanometers provide accurate pressure measurements when
a proper maintenance protocol is followed.
From the Division of Hypertension, Mayo Clinic, Rochester, Minn.
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