Expert alarm system to predict critical hypotension before serious events

Even in the latest anesthesia/critical care monitors, an alarm is only evok ed when a parameter breaks the reference level. There is no commercial prod uct that evokes an alarm before reaching a critical level. Generally, the e xpert anesthesiologists often predict critical hypotension far before serio us events occur, since they can recognize trends in blood pressure (BP). The author has introduced a new alarm system, which is based on the expert system that estimates BP. The program was developed with Future BASIC ver 2 .3 (Staz Software, USA) under Mac OS system 7.6.1J using Macintosh PowerBoo k (Apple computer, USA). The basic principle is as follows: The continuous data of either the invasi ve BP or the noninvasive tonometry BP of the vital sign monitor (BP-508, Co lin, Japan) are sampled every 30 s. The rate of change is obtained by the l inear least-significant regression procedure from the latest 10 points. Thi s regression line is then extrapolated 5 min further. When the future BP ex ceeds either the alert or warning level, the visible and audible alarm is e voked. The visual trend graph is added to check the estimation. This alarm system could reproduce a similar level of recognition of BP tren ds as the board-certificate anesthesiologist.