Chest
Volume 142, Issue 2, August 2012, Pages 367-376
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Original Research
Critical Care
Patient-Ventilator Asynchrony During Noninvasive Ventilation: A Bench and Clinical Study

https://doi.org/10.1378/chest.11-2279Get rights and content

Background

Different kinds of ventilators are available to perform noninvasive ventilation (NIV) in ICUs. Which type allows the best patient-ventilator synchrony is unknown. The objective was to compare patient-ventilator synchrony during NIV between ICU, transport—both with and without the NIV algorithm engaged—and dedicated NIV ventilators.

Methods

First, a bench model simulating spontaneous breathing efforts was used to assess the respective impact of inspiratory and expiratory leaks on cycling and triggering functions in 19 ventilators. Second, a clinical study evaluated the incidence of patient-ventilator asynchronies in 15 patients during three randomized, consecutive, 20-min periods of NIV using an ICU ventilator with and without its NIV algorithm engaged and a dedicated NIV ventilator. Patient-ventilator asynchrony was assessed using flow, airway pressure, and respiratory muscles surface electromyogram recordings.

Results

On the bench, frequent auto-triggering and delayed cycling occurred in the presence of leaks using ICU and transport ventilators. NIV algorithms unevenly minimized these asynchronies, whereas no asynchrony was observed with the dedicated NIV ventilators in all except one. These results were reproduced during the clinical study: The asynchrony index was significantly lower with a dedicated NIV ventilator than with ICU ventilators without or with their NIV algorithm engaged (0.5% [0.4%-1.2%] vs 3.7% [1.4%-10.3%] and 2.0% [1.5%-6.6%], P < .01), especially because of less auto-triggering.

Conclusions

Dedicated NIV ventilators allow better patient-ventilator synchrony than ICU and transport ventilators, even with their NIV algorithm. However, the NIV algorithm improves, at least slightly and with a wide variation among ventilators, triggering and/or cycling off synchronization.

Section snippets

Materials and Methods

This study involved a bench part and a clinical part. An extensive description of both the bench and clinical protocols is provided in e-Appendix 1.

Triggering Delay

The ICU and transport ventilators with their NIV algorithm turned off in the absence of leaks exhibited a total triggering delay (TD) of 117 milliseconds (99-131 milliseconds) and 143 milliseconds (114-174 milliseconds), respectively (P = .37) (Fig 2). The addition of inspiratory leaks did not significantly modify these values except for the Engstrom, G5, and T1, which had an increased TD, and the Medumat, which showed a reduced TD. Turning on the NIV algorithm while maintaining inspiratory

Discussion

To our knowledge, this study is the first to compare patient-ventilator synchronization during NIV between ICU, transport, and dedicated NIV ventilators, with both a bench and a clinical evaluation. The observations made with these two approaches were consistent, offering a strong validation of the bench model, a logical explanation for the clinical data, and lending strength to the main results of this study, which are:

  • In NIV conditions, most dedicated NIV ventilators allowed better

Conclusion

In conclusion, our study shows that dedicated NIV ventilators allow a better patient-ventilator synchrony in the presence of leaks than ICU and transport ventilators, even if their NIV algorithm is engaged, especially for what concerns auto-triggering. When using an ICU or transport ventilator to perform NIV, the NIV algorithm usually improves, at least slightly and with variations among ventilators, triggering and/or cycling synchronization.

Acknowledgments

Author contributions: Dr Carteaux is the guarantor of the paper.

Dr Carteaux: contributed to the study design, patient enrollment, data collection, data analysis, data interpretation, and manuscript preparation, and read and approved the final manuscript.

Dr Lyazidi: contributed to the study design, patient enrollment, data collection, data analysis, data interpretation, and manuscript preparation, and read and approved the final manuscript.

Dr Cordoba-Izquierdo: contributed to the study design,

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    For editorial comment see page 274

    Funding/Support: This study was supported in part by a research grant from Philips Respironics (€10,000). This study was performed while Dr Carteaux was funded by an institutional grant, the Année Recherche, from the Ministère de l'éducation nationale, de l'enseignement supérieur et de la recherche (French Ministry for Education and Research).

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.

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