Near-continuous, noninvasive blood pressure monitoring in the out-of-hospital setting

Objectives. This study was conducted to test out-of-hospital performance of a noninvasive radial artery tonometry device to assess blood pressure (BP), providing readings every 10-12 seconds. The primary objective was to determine the correlation between noninvasive BPs calculated with radial artery tonometry and standard oscillometric cuff methods. The secondary objective was to determine whether the difference observed between the two techniques was consistent over the range of BPs measured. Methods. This prospective trial enrolled adults transported by helicopter (n = 9 patients), fixed-wing airplane (n = 1), or ground vehicle (n = 10) of a single transport service. Patients had BP assessed simultaneously, by both standard automatic cuff and radial artery tonometry device, every 5 minutes. Data were assessed with correlation coefficients, and Bland-Altman techniques were utilized to assess for bias over the range of mean arterial pressures (MAPs) encountered. For all tests, p was set at 0.05. Results. No major problem with radial artery tonometry device field performance was noted. There were 139 pairs of MAP assessments in 20 patients. The correlation coefficient for the two assessment modalities was 0.96. Bland-Altman bias plot and Pitman's test (p = 0.11) revealed good correlation between the two assessment mechanisms over the entire range of MAPs (42 to 163 mm Hg) encountered in the study. Conclusion. The radial artery tonometry device provided MAP assessments that were highly correlated with readings from a standard oscillometric device. The radial artery tonometry device performed well in a variety of patient types and in multiple transport vehicles, and there was no sign that its performance was adversely affected by the out-of-hospital setting.