Ma. Kaufmann et al., OSCILLOMETRIC BLOOD-PRESSURE MEASUREMENTS BY DIFFERENT DEVICES ARE NOT INTERCHANGEABLE, Anesthesia and analgesia, 82(2), 1996, pp. 377-381
Blood pressure (BP) is frequently measured in patients by noninvasive
blood pressure (NIBP) monitors. Values obtained by oscillometric devic
es of different brands may appear in one patient's record as if they w
ere interchangeable; their concordance, however, has not been establis
hed. In 25 patients with major depression who were treated with electr
oconvulsive therapy (ECT) BP was measured on either arm by devices man
ufactured by SpaceLabs (SpL, 12 patients, 182 data points) and Marquet
te (Marq, 13 patients, 193 data points), respectively, and comparisons
were made with simultaneous measurements on the opposite arm by Dinam
ap 1846SX (DIN), during the awake state and at 1-min intervals up to 5
-7 min after ECT. Because ECT is associated with an intense, but short
-lasting hyperdynamic state, comparisons of BP values could be made ov
er a wide range of pressures. Bland-Altman plots were constructed to s
how the distribution of pressure differences at all pressures. Agreeme
nts between two instruments were judged according to guide lines by th
e American Association for Advancement of Medical Instrumentation (AAM
I). The standard deviation of the difference (SDD) between two DIN dev
ices was 7 nun Hg for systolic (SEP) and 6.3 mm Hg for diastolic blood
pressure (DBP), whereas mean differences were 0.9 and 0.2 nun Hg, res
pectively (P = not significant [NS]), thus showing reproducibility. Co
rresponding SDD values SpL versus DIN were 9.1 for SEP and 8.3 nun Hg
for DBP, while the mean differences were 1.6 (P = 0.026) and 7.3 (P =
0.0001) mm Hg, respectively. Corresponding SDD values for Marq versus
DIN were 11.8 and 9.7 mm Hg with mean differences of 0.8 (P = NS) and
0.3 (P = NS) mm Hg. Whereas SEP differences DIN versus DIN exceeded 10
mm Hg in only 10% of observations, they exceeded that threshold in 31
% and 32% of observations for SpL versus DIN and Marq versus DIN, resp
ectively. In view of the variability that exceeds the AAMI guidelines
and the one out of three occurrence of individual SEP differences exce
eding 10 mm Hg for comparisons of SpL or Marq versus DIN, measurements
by these three oscillometric devices are not interchangeable.