EVALUATION OF A KNOWLEDGE-BASED SYSTEM PROVIDING VENTILATORY MANAGEMENT AND DECISION FOR EXTUBATION

We evaluated whether a knowledge-based system (KBS) connected to a ven tilator in pressure support mode could correctly predict the ability o f patients to tolerate total withdrawal from ventilatory support. The KBS was designed to continuously adapt ventilatory assistance to the n eeds of the patient, to manage a strategy of gradually decreasing vent ilatory assistance, and to indicate when the patient was able to breat he without assistance. Thirty-eight patients for whom weaning was bein g considered were evaluated using a conventional battery of parameters , including weaning criteria, tolerance of a T-piece trial, and outcom e 48 h after permanent withdrawal of ventilation. The results of this evaluation were compared with the suggestions made by the KBS at the e nd of a period of KBS-driven mechanical ventilation inserted in the co nventional weaning procedure. The positive predictive value of the KBS was 89%, versus 77% for the conventional procedure and 81% for the ra pid shallow breathing index alone. The KBS correctly predicted the cou rse of five patients who tolerated a T-piece trial but required ventil ation within 48 h. We conclude that our KBS ensured appropriate patien t management during the weaning period and improved our ability to pre dict responses to weaning.