The Science Journal of the American Association for Respiratory Care

2002 OPEN FORUM Abstracts

EVALUATION OF INSPIRATORY RISE TIME AND WORK OF BREATHING IN THE SERVOi ® VENTILATOR.

Mark J. Heulitt MD, Patricia C. Wankum MD, Shirley J. Holt RRT, Tracy L. Thurman. Pediatrics, UAMS/Arkansas Children?s Hospital, Little Rock, AR.

Background: Work of breathing (WOB) for pediatric and neonatal patients supported on mechanical ventilation relates to both patient effort and response time of the ventilator. Recent advances in mechanical ventilators include incorporation of computer controlled active exhalation valves to improve response time thus decrease WOB.

Objective: The objective was to evaluate the effects of an active exhalation valve on WOB and the response time during changing inspiratory flow or inspiratory rise time (IRT) on the Siemens Servoi ?.

Methods: Six neonatal and six pediatric ventilated spontaneously breathing piglets were studied in pressure support (2 cm H2O), PEEP (2 cm H2O) with IRT 0%, 5%, 10% and 20%, utilizing flow triggering. Data were collected using both a computerized respiratory monitor and data acquisition system to evaluate differences in the duration of inspiratory effort, trigger response time, and any significant pressure or flow variances relating to IRT. Response time of the ventilator included quantification of the slope of the inspiratory flow curve and the area of flow from the baseline pressure to when expiration began. In addition, WOB was measured.

Results: When comparing all levels of IRT, no differences in WOB were found in neonatal or pediatric animals. When waveforms were compared, we found no differences in the animals? effort to trigger. We also found no differences in slope.

Conclusions: In healthy animals, since the active exhalation valve optimizes flow, the lack of differences with changes in IRT can be explained by the ability of the active exhalation valve to respond to the animal?s effort or needs.

Disclosure: Unrestricted grant from Siemens Medical Systems

OF-02-089

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