The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts

WORKLOAD MEASUREMENTS OF 5 DIFFERENT NONINVASIVE PRESSURE-TARGETED VENTILATORS DURING VARIOUS LEVELS OF INSPIRATORY DEMAND AND OXYGEN TITRATION: A BENCH TEST STUDY.

Michael D. Coutts, RRT, Kelly Jager, RRT, Martin Tweedale, MB, PhD. Vancouver Hospital & Health Science Centre, Vancouver, British Columbia, Canada

Introduction: The number of noninvasive pressure-targeted ventilators being developed have increased dramatically over the past few years. The purpose of this study is to compare 5 different models of pressure-targeted ventilators (PTVs) when different levels of inspiratory demand and different levels of titrated oxygen flow are applied. Methods: A two chambered lung model was used with one side attached to the PTV and the other side attached to a ventilator (PB 7200ae), which simulated the patient efforts. A leak was maintained in the NIV circuit using a Respironics whisper swivel. Two PTVs of each model were tested (STD 30 BiPAP, PB 335, PB 320b, Quantum, and VPAP) and three consecutive breaths were recorded for each test. Each test was done at flowrates of 30, 60, 90, and 120 L/min and at oxygen flowrates of 5, 10, 15 L/min, and flush. All PTVs were tested at IPAP of 10 cmH_{2}O and EPAP of 4 cmH_{2}O. The response time (Tr), rise time, and maximum negative pressure (Pneg) was determined. Statistical analysis was done by ANOVA with differences considered significant when p < = 0.05. Results: Significant differences between all PTVs were noted throughout all testing levels. During testing of oxygen titration the Quantum had a Tr that was slower and had a Pneg that was more negative than the other PTVs, the rise times were consistent throughout all machines. During testing of the different flowrates the results varied between the different PTV. At a ventilator flowrate of 60L/min the PB 335 and PB 320b achieved the fastest rise time. The STD 30, PB 335 and VPAP had the best Tr. The Std 30, PB 320b and VPAP obtained the lowest Pneg. Mean values at a ventilator flowrate of 60 l/min are listed below.

Quantum STD 30 PB 335 PB 320b VPAP

Rise Time(s) .35±0.04 .40±0.10 .20±0.05* .29±0.04 .54±0.01

Tr(s) .42±0.03 .12±0.02 .18±0.02 .26±0.2 .14±0.02

[star] [star] [star]

Pneg (cmH_{2}O) -1.76±0.46# -.66±0.25 -1.08±0.10 -.81±0.27 -.44±0.06

[box]

* p < = 0.01 PB 335 significantly lower rise time vs Quantum, VPAP, STD 30

[star] p < = 0.01 STD 30, PB 335, VPAP significantly lower Tr vs Quantum, PB 320b

# p < = 0.01 Quantum significantly higher Pneg vs STD 30, PB 335, PB 320b, VPAP

[box] p < = 0.01 PB 335 significantly higher Pneg vs VPAP

Conclusions: As the data indicates there are differences between all the PTV. Each PTV achieved optimal values in one or more of the measured parameters. Therefore it is difficult to make a clear decision as to which PTV performs optimally in all testing situations. This data was obtained from a bench test perspective therefore, to make a definitive decision on a specific bilevel unit further studies should be performed within the clinical setting.

OF-97-034

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