Can we trust ambulatory blood pressure monitors? Might a postural adjustment model improve accuracy & reliability

The hypertensive disorders of pregnancy remain a significant problem in antenatal care. The measurement of blood pressure in pregnancy is fundamental in diagnosing and managing these conditions. The introduction of technology in the form of ambulatory automated blood pressure monitors has allowed multiple, standardised measurements to be made away from the clinical environment, and has addressed many of the errors associated with conventional sphygmomanometry. This article explores the potential role of ambulatory blood pressure monitoring in pregnancy.

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Abstract P200: Oscillometric Ambulatory Blood Pressure Monitors Are Prone To Clinically & Statistically Significant Errors When Tested In A Controlled Laboratory Setting

Hypertension ◽

10.1161/hyp.76.suppl_1.p200 ◽

2020 ◽

Vol 76 (Suppl_1) ◽

Author(s):

V. P Lombardi ◽

Patrick C Reichhold ◽

Jennifer L Cramer ◽

Hannah P Harkness ◽

Natalie J DeBell ◽

...

Keyword(s):

Blood Pressure ◽

Ambulatory Blood Pressure ◽

Cuff Pressure ◽

Field Testing ◽

Laboratory Setting ◽

Essential Component ◽

Blood Pressure Monitors ◽

Extreme Variability ◽

Testing Protocols ◽

Level Of Agreement

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.

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