Chest
Volume 136, Issue 2, August 2009, Pages 448-456
Journal home page for Chest

Original Research
Critical Care Medicine
Bilevel vs ICU Ventilators Providing Noninvasive Ventilation: Effect of System Leaks: A COPD Lung Model Comparison

https://doi.org/10.1378/chest.08-3018Get rights and content

Background

Noninvasive positive-pressure ventilation (NPPV) modes are currently available on bilevel and ICU ventilators. However, little data comparing the performance of the NPPV modes on these ventilators are available.

Methods

In an experimental bench study, the ability of nine ICU ventilators to function in the presence of leaks was compared with a bilevel ventilator using the IngMar ASL5000 lung simulator (IngMar Medical; Pittsburgh, PA) set at a compliance of 60 mL/cm H2O, an inspiratory resistance of 10 cm H2O/L/s, an expiratory resistance of 20 cm H2O/L/s, and a respiratory rate of 15 breaths/min. All of the ventilators were set at 12 cm H2O pressure support and 5 cm H2O positive end-expiratory pressure. The data were collected at baseline and at three customized leaks.

Main results

At baseline, all of the ventilators were able to deliver adequate tidal volumes, to maintain airway pressure, and to synchronize with the simulator, without missed efforts or auto-triggering. As the leak was increased, all of the ventilators (except the Vision [Respironics; Murrysville, PA] and Servo I [Maquet; Solna, Sweden]) needed adjustment of sensitivity or cycling criteria to maintain adequate ventilation, and some transitioned to backup ventilation. Significant differences in triggering and cycling were observed between the Servo I and the Vision ventilators.

Conclusions

The Vision and Servo I were the only ventilators that required no adjustments as they adapted to increasing leaks. There were differences in performance between these two ventilators, although the clinical significance of these differences is unclear. Clinicians should be aware that in the presence of leaks, most ICU ventilators require adjustments to maintain an adequate tidal volume.

Section snippets

Materials and Methods

Nine ICU mechanical ventilators and one bilevel ventilator (Table 1) were compared using the ASL5000 lung simulator (IngMar Medical; Pittsburgh, PA) with increasing system leaks. The ASL5000 is a computerized lung simulator consisting of a piston moving inside a cylinder.13 Compliance, resistance, and the inspiratory muscle pressure profile (negative pressure created by respiratory muscles) are set by the user.

Each ventilator evaluated was connected to the ASL5000 by the manufacturer's standard

Baseline Performance

The trigger pressure was smaller for the Esprit, Vision (Respironics), Vela, PB840 (Puritan Bennett; Boulder, CO), and Raphael (Hamilton Medical AG; Rhazuns, Switzerland) ventilators than for the other ventilators (Fig 3). Trigger pressure was greater for the Servo I (Maquet; Solna, Sweden), e360 (Newport), e500, and e500 auto. The time to trigger was shortest for the Esprit (approximately 100 ms) and longest for the iVent (VersaMed; Pearl River, NY) and Esprit Auto-Trak (approximately 160 ms) [

Discussion

The main findings of this study are as follows: (1) at baseline, all ventilators were able to deliver adequate tidal volume, maintain airway pressure, and synchronize with the simulator, without missed efforts or auto-triggering; (2) as the leak was sequentially increased, all ventilators, except for the Vision and the Servo I, needed adjustment of sensitivity and/or inspiratory termination criteria to maintain synchrony, and some ventilators transitioned to backup ventilation; and (3) the

Acknowledgments

Author contributions: All authors contributed to the design of the study, the evaluation of the results, and the writing of the manuscript. Data gathering was primarily preformed by Dr. Ferreira and Mr. Chipman. Data analysis was primarily preformed by Dr. Ferreira.

Financial/nonfinancial disclosures: Dr. Kacmarek has received research grants and honorariums for lecturing from Hamilton Medical, Puritan-Bennett Corp, Respironics Inc. Cardinal Medical, Drager Medical, Newport, and Maquet Medical

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Funding/Support: This study was partially funded by an unrestricted grant from Respironics Inc. Dr. Ferreira was partially funded by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Brazil.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/site/misc/reprints.xhtml).

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