Background: The aneroid sphygmomanometer is commonly used for the indirect
measurement of blood pressure despite significant concerns about its accura
cy. Although the mercury sphygmomanometer is highly accurate, there are con
cerns about the environmental toxicity of mercury. In response to various e
xternal pressures to become essentially mercury free, the Mayo Clinic, Roch
ester, Minn, has replaced many mercury sphygmomanometers with aneroid devic
es. Since 1993, a maintenance protocol has been in place to ensure proper f
unction and accuracy of these devices.
Methods: We assessed the accuracy of 283 aneroid devices using as the refer
ence 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 mer
cury at each reference point (at 20-mm Hg intervals from 60 to 240 mm Hg de
fined 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 210 (r=0.99; P<.001). The values from the aneroid device underestimat
ed those of the reference device by a mean of 0.5 mm Hg (95% confidence int
erval, 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 measurement
s when a proper maintenance protocol is followed.