An expert system for monitor alarm integration.
OBJECTIVE
Intensive care and operating room monitors generate data that are not fully utilized. False alarms are so frequent that attending personnel tends to disconnect them. We developed an expert system that could select and validate alarms by integration of seven vital signs monitored on-line from cardiac surgical patients.


METHODS
The system uses fuzzy logic and is able to work under incomplete or noisy information conditions. Patient status is inferred every 2 seconds from the analysis and integration of the variables and a unified alarm message is displayed on the screen. The proposed structure was implemented on a personal computer for simultaneous automatic surveillance of up to 9 patients. The system was compared with standard monitors (SpaceLabs PC2), using their default alarm settings. Twenty patients undergoing cardiac surgery were studied, while we ran our system and the standard monitor simultaneously. The number of alarms triggered by each system and their accuracy and relevance were compared. Two expert observers (one physician, one engineer) ascertained each alarm reported by each system as true or false.


RESULTS
Seventy-five percent of the alarms reported by the standard monitors were false, while less than 1% of those reported by the expert system were false. Sensitivity of the standard monitors was 79% and sensitivity of the expert system was 92%. Positive predictive value was 31% for the standard monitors and 97% for the expert system.


CONCLUSIONS
Integration of information from several sources improved the reliability of alarms and markedly decreased the frequency of false alarms. Fuzzy logic may become a powerful tool for integration of physiological data.
Oberli
C
C
Department of Electrical Engineering, Catholic University of Chile, School of Engineering, Santiago de Chile, Chile.
Urzua
J
J
Saez
C
C
Guarini
M
M
Ciprianio
A
A
Garayar
B
B
Lema
G
G
Canessa
R
R
Sacco
C
C
Irarrazaval
M
M
D001784:Blood Gas Analysis; D006348:Cardiac Surgical Procedures; D004562:Electrocardiography; D005103:Expert Systems; D005189:False Positive Reactions; D017143:Fuzzy Logic; D006439:Hemodynamics; D006801:Humans; D007431:Intraoperative Complications / Q000175:diagnosis*; D016343:Monitoring, Intraoperative; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D018511:Systems Integration