The Science Journal of the American Association for Respiratory Care

2002 OPEN FORUM Abstracts

Evaluation of a Computerized Closed Loop Ventilator Mode, Using a Neonatal Porcine MODEL

Mark J. Heulitt MD, Patricia C. Wankum MD, Stacy M. McBain , Shirley J. Holt RRT, Tracy L. Thurman and Katherine L. Menees 1. Pediatrics, UAMS/Arkansas Children?s Hospital, Little Rock, AR.

Background: Weaning mechanical ventilation in patients optimally includes meeting their needs by making frequent ventilator adjustments. Computerized closed loop ventilation (CLV) is designed so the ventilator can be interactive with the patient?s needs by making breath by breath adjustments in both control and support modes.

Objective: The objective was to document the level of work of breathing (WOB) and to validate that a CLV ventilator algorithm responded aptly using a neonatal animal model with drug induced apnea.

Methods: We ventilated six sedated piglets using CLV in PRVC/VS, PC/PSV,VC/ VS. Data were collected using both a computerized respiratory monitor and data acquisition system. Data collection began with the animals breathing spontaneously in each support mode followed by the administration of a short acting neuro-muscular blocker to induce apnea, thus allowing the ventilator to switch between modes automatically. Data were collected before, during, and after apnea to observe the duration of inspiratory effort, trigger response time, and any significant pressure or flow variances of the CLV feature. In addition, patient WOB (WOBp) was measured before and after each phase.

Results: We found no instances of CLV failure to follow the predetermined algorithms. There was a difference in duration of inspiratory effort by each animal during triggering in the post-paralysis phase for PC/PS (p<0.05). Maximum flow reached was lower in the post-paralysis phase for PC/PS (p<0.05). We also found WOBp decreased in the post-paralysis phase for all modes tested (p<0.05).

Conclusions: We conclude that differences in response time and maximum flow reached were due to continued weakness from the neuromuscular blocker.

Disclosure: Unrestricted grant from Siemens Medical


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