A clinical evaluation of rapid automatic noninvasive blood pressure determination with the Ohmeda 2120 "return-to-flow" method.

Most commercial noninvasive blood pressure devices use the oscillometric method for determination of blood pressure. The Ohmeda 2120 noninvasive blood pressure monitor uses the oscillometric technique, but it also includes a "Sys Stat" mode for rapid determination of systolic blood pressure up to ten times per minute. This Sys Stat mode uses the "return-to-flow" method, in which the pressure on an upper arm cuff decreases in small steps until a finger sensor detects the first pulse of blood. Data from 16 patients monitored with the Ohmeda 2120 unit and with an arterial cannula were analyzed. The line of regression was Sys Stat = 0.85 (arterial) + 9.49. The Ohmeda 2120 monitor tended to underestimate the arterial pressure, particularly at higher pressures. Several factors could have contributed to this underestimation. Even so, the accuracy is sufficient for clinical use under most circumstances. More importantly, in an urgent situation, the Sys Stat mode can provide a reading of systolic blood pressure within seconds.