The validity of emergency department triage blood pressure measurements

Objective: Automated blood pressure (ABP) devices are ubiquitous at emergency department (ED) triage. Previous studies failed to evaluate ABP devices against accepted reference standards or demonstrate triage readings as accurate reflections of blood pressure (BP). This study evaluated ED triage measurements made using an ABP device and assessed agreement between triage BP and BP taken under recommended conditions. Methods: A prospective study was conducted at an urban teaching hospital. Patients were enrolled by convenience sampling. Simultaneous automated and manual triage BPs were obtained using one BP cuff with a Y-tube connector. Research assistants were certified in obtaining manual BP as described by the British Hypertension Society (BHS). Patients were placed in a quiet setting, and manual BP was repeated by American Heart Association (AHA) standards. Data analysis was performed using methods described by Bland and Altman. The ABP device was assessed using Association for the Advancement of Medical Instrumentation (AAMI) and BHS criteria. Results: One hundred seventy-one patients were enrolled. Systolic BP (sBP) range was 81 to 218 mm Hg; diastolic BP (dBP) range was 43 to 130 mm Hg. Automated vs. manual sBP difference was 3.8 +/- 11.2 mm Hg (95% confidence interval [CI] = 2.1 to 5.4); dBP difference was 6.6 +/- 9.0 mm Hg (95% CI = -7.9 to -5.2). Manual triage BP vs. AHA standard SBP difference was 11.6 +/- 12.8 mm Hg (95% CI = 9.1 to 14.1); dBP difference was 9.9 +/- 10.4 mm Hg (95% CI = 7.9 to 12.0). The ABP device failed to meet AAMI criteria and received a BHS rating of "D." Poor operator technique and extraneous patient and operator movement appeared to hamper accuracy. Conclusions: ABP triage measurements show significant discrepancies from a reference standard. Repeat measurements following AHA standards demonstrate significant decreases in the measured blood pressures.