The Science Journal of the American Association for Respiratory Care

2002 OPEN FORUM Abstracts

EVALUATION OF INSPIRATORY RISE TIME AND WORK OF BREATHING.

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: In adult patients, changing the inspiratory flow rate has been shown to improve patient-ventilator synchrony. However, little is known about the effects of increasing inspiratory flow on work of breathing (WOB) in neonatal and pediatric patients.

Objective: The objective was to evaluate the effects of inspiratory rise time (IRT) on WOB and the response time of the ventilator.

Methods: Twelve neonatal and 12 pediatric intubated, sedated, spontaneously breathing piglets were ventilated in pressure support ventilation (2 cm H2O), PEEP (3 cm H2O) with IRT 1% and 10%, utilizing flow triggering on the Servo 300TM. 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 IRT 1% to IRT 10% we found no differences in WOB in neonatal animals, however, there were differences for ventilator work in pediatric animals (p=0.002). When waveforms were compared, we found no differences in the animals? effort to trigger, however, we found differences in ventilator response time. In neonatal animals, the slope of inspiratory flow was faster for IRT 1% (174%, p=0.002). The same was true for pediatric animals (113%, p=0.002).

Conclusions: Adjusting the IRT, had no effect on WOB in healthy neonatal and pediatric animals, but did affect the availability of flow during triggering of the ventilator.

Disclosure: Unrestricted grant from Siemens Medical Systems

OF-02-091

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