Out-of-hospital use of a pulse oximeter to determine systolic blood pressures.

ABSTRACT

STUDY OBJECTIVE: Blood pressure (BP) in the out-of-hospital setting is one of the most important diagnostic tools used by emergency medical services (EMS) providers. Conventional methods of palpation and auscultation can be time consuming, and the measurements often are inaccurate because of the adverse working conditions encountered. Pulse oximetry waveform systolic blood pressure (POWSBP) measurement has been used successfully in emergency departments to monitor BP. The objective of this study was to compare the accuracy of field POWSBP measurements obtained by noninvasive electronic BP measurement (NIBPM), auscultation, and palpation in the out-of-hospital environment. DESIGN: Blood pressure measurements used for this study were obtained by POWSBP, NIBPM (PROPAQ model 102; Protocol Systems, Beaverton, Oregon USA), auscultation, and palpation on patients in moving ambulances. Measurement of POWSBP was accomplished by observing the return of the waveform on the pulse oximeter at the time of cuff deflation. The order in which the readings were obtained as well as the arm chosen for measurement were randomized. SETTING AND PARTICIPANTS: Paramedics and emergency medical technicians in an urban, inner-city emergency medical services (EMS) system. MEASUREMENTS AND MAIN RESULTS: Blood pressure measurements were sampled from 69 patients. Regression analysis identified significant correlation between POWSBP and the four methods utilized, with r = 0.92 for NIPBM, r = 0.95 for auscultation, and r = 0.97 for palpation, all significant at p < 0.0001. CONCLUSIONS: The use of POWSBP measurement is a fast, easy, and accurate technique with which to measure systolic BP in the field. It may have special importance for noisy environments and moving vehicles in which conventional methods of auscultation or palpation may be difficult.