Browsing by Author "Garayar, B"

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    An expert system for monitor alarm integration
    (1999) Oberli, C; Urzua, J; Saez, C; Guarini, M; Cipriano, A; Garayar, B; Lema, G; Canessa, R; Sacco, C; Irarrazaval, M
    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 uni ed 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 (Space-Labs (TM) 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.
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    Comparison of two doses of aprotinin in patients receiving aspirin before coronary bypass surgery
    (ARNOLD, HODDER HEADLINE PLC, 2000) Moran, SV; Lema, G; Medel, J; Irarrazaval, MJ; Zalaquett, R; Garayar, B; Flaskamp, R
    This study was designed to evaluate efficacy and tolerability of two different doses of aprotinin in patients receiving aspirin before undergoing coronary artery bypass grafting. Forty-two patients were randomized to receive either placebo (group I), or aprotinin in doses of 4 000 000 KIU (group II) or 6 000 000 KIU (group III). Drug efficacy was determined by measuring postoperative blood loss and transfusion of blood products. Both doses were effective in reducing blood loss and transfusion requirements. Blood loss through thoracotomy drainage was 450 +/- 224, 182 +/- 144, 142 +/- 98 mi, respectively, for control and treatment groups II and III (p = 0.0001). The numbers of patients with blood transfusions were seven (50%), two (17%) and two (17%) for group I and treatment groups II and ill, respectively (p = 0.10). Tolerability was excellent and complications few and reversible.