Purpose:
To compare the accuracy & level of agreement of Oscar 2 & Spacelabs 90207 ABPMs with 2 observers (O1O2) using an Hg column & ThinkLabs digital stethoscope.
Methods:
O1O2 measured simultaneous same arm Hg column BPs & ABPMs assessed simultaneous opposite arm BPs in triplicate in 17 seated subjects (7 ♀, 10 ♂). Supine, seated & standing BPs were measured using non-dominant relaxed arms in 12 subjects.
Hypotheses:
ABPM & O1O2 BPs would differ clinically & statistically with accuracy based on posture because ABPM proprietary equations are derived from seated BPs & use peak cuff pressure to estimate systolic (SBP) & diastolic (DBP) pressures.
Results:
For seated subjects, the Oscar overestimated O1O2 SBP by ~ 10 mm Hg (Δ = -9.8 ± 9.4 mm Hg, P < 0.001), but with extreme variability as 95% of Oscar SBPs were 9.0 mm Hg below to 28.7 mm Hg above O1O2. The Spacelabs overestimated O1O2 SBP by ~ 5 mm Hg (Δ = -5.2 ± 7.8 mm Hg, P < 0.001) with 95% of Spacelabs SBPs 10.5 mm Hg below to 20.9 mm Hg above O1O2. There was a stepwise increase in the Oscars’ SBP overestimation of Hg column BPs from supine (-3.1 mm Hg, P < 0.01), to seated (-5.3 mm Hg, P < 0.001) to standing (-6.6 mm Hg, P < 0.01). The Oscar overestimated supine (-7.0 mm Hg, P < 0.001), but underestimated standing (3.9 mm Hg, P < 0.05) DBPs. The Spacelabs also overestimated supine (-6.5 mm Hg, P
<
0.001), but underestimated standing (4.8 mm Hg, P < 0.01) DBPs.
Conclusions:
Our results confirm that leading oscillometric ABPMs are prone to clinically & statistically significant errors even in a controlled lab setting. Given that ABPMs are motion intolerant & unable to assess & adjust for a patient’s posture, errors will be compounded during 24-hr field testing. Results will vary based on the ABPM & postural %s assumed by each patient. International & national ABPM testing protocols must be strengthened & require postural testing as an essential component of validation.
0270 : Ambulatory blood pressure monitors in our daily practice: why use it more often?
