The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts

TIDAL VOLUME PRECISION OF NEONATAL VOLUME-TARGETED, SPONTANEOUS MODES IN AN ACTIVE AND PASSIVE INFANT LUNG MODEL.

Dave N. Crotwell, Rob DiBlasi; Respiratory Care, Seattle Children’s Hospital and Research Institute, Seattle, WA

BACKGROUND:Volume-targeted spontaneous modes are used in premature infants to provide a consistent tidal volume (VT). We evaluated 4 neonatal ventilator’s ability to maintain target VT with changes in condition and respiratory effort. We hypothesized that there would be no difference in the delivered VT between ventilator brands while varying mechanics and respiratory effort in a premature infant lung model. METHODS:4 neonatal ventilators were tested using volume-targeted spontaneous modes, including:1) GE Carestation(PSV-VG); Marquet Servo-i(PRVC-Auto Mode); Drager Babylog8000 plus(PSVG); Carefusion Avea(Machine Volume-Flow Cycle). A standard infant disposable patient circuit and humidifier was attached to each ventilator and a circuit test was performed.The ventilators were set at VT=5 mL, BU RR 40 b/min, PEEP 5 cmH2O, and FIO2 0.21. Gases were humidified at 37∞C before testing. When available, the ventilator was set to limit volume delivery at 125-130% of the set VT. The Ingmar ASL 5000 was configured using a customized breath sequence (n=265) of erratic, spontaneous and apneic breathing patterns with ongoing changes in mechanics and breathing effort. Each ventilator was attached to the ASL 5000 with a 2.5mm ID ET tube. Breath to breath VT delivery was measured using ASL software version 3.0 for the entire breath sequence. Data were compared using ANOVA with SNK for post-hoc analyses. The precision of VT delivery was calculated using coefficient of variation (CV). RESULTS:Delivered VT was lower during AVEA (Machine Volume-flow cycle) than with any other ventilator tested (P < 0.05; Figure). The CV for each ventilator tested was: Servo-I 22%, Carestation 12%, AVEA 40%, and BabyLog 8000 plus 33%. CONCLUSION/DISCUSSION:It appears that neonatal ventilators servo-control pressure to maintain small VT within an acceptable clinical range when exposed to breathing patterns that are commonly experienced by premature infants. The AVEA ventilator had a tendancy deliver a lower VT than targeted initially. The Avea targets an uncorrected volume measured at the ventilator gas outlet, not at the proximal flow sensor. The Carestation ventilator had the best VT precision as noted by the lowest CV value. While these data may be important for ventilating premature infants, we only tested one of each specified ventilator brand. Additional testing using more ventilators is needed before any inferences can be made about the performance of these modes in premature infants. Sponsored Research - None