Comparison of Portapres® with standard sphygmomanometry in pregnancy

Background: Continuous beat-to-beat noninvasive blood pressure (BP) measurement is possible with Portapres(R). It constructs finger arterial waveforms beat-to-beat. Dedicated software is used to analyze the arterial waveforms. A new technique has been developed to reconstruct brachial intraarterial pressure that uses return to flow (RTF). This method has been validated against invasive intraarterial measurements in nonpregnant individuals. Objectives: To validate Portapres in normal and preeclamptic pregnant women against standard aneroid sphygmomanometry according to Riva-Rocci-Korotkoff (RRK). Methods: In 30 normotensive (10 in each trimester) and 20 preeclamptic women, two trained observers blinded from each other's results took BP measurements with a standard sphygmomanometer. These measurements were compared with sequential same-arm averaged measurements obtained during 30 sec by Portapres, following protocols from the Association for the Advancement of Medical Instrumentation (AAMI, mean accepted difference less than or equal to 5 mm Hg, SD less than or equal to 8) and British Hypertension Society (BHS, gradings A down to D). Results: A total of 150 measurement pairs were analyzed. Cumulative percentages of absolute pressure differences for all women (BHS) and mean pressure differences (SD) for different trimesters and preeclampsia (AAMI) between sphygmomanometry and Portapres were calculated. Overall, mean difference (SD) for systolic BP was 5 (SD 8) and for diastolic BP was - 3 (SD 8), although analysis of variance revealed a significant effect for preeclampsia on diastolic differences between the two methods of BP measurement (p<0.001). Conclusions: Portapres with RTF developed to equal intraarterial brachial pressure, compares reasonably well to RRK and overall meets the criteria set by the AAMI. According to the BHS, Portapres receives a B-grading for diastolic BP and a C-grading for systolic BP. As Portapres measures BP and calculates cardiac output continuously and noninvasively, it would appear worthwhile to further evaluate this device in pathological pregnancies.