Chest
Volume 141, Issue 2, February 2012, Pages 469-476
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Original Research
Respiratory Care
Monitoring of Noninvasive Ventilation by Built-in Software of Home Bilevel Ventilators: A Bench Study

https://doi.org/10.1378/chest.11-0485Get rights and content

Background

Current bilevel positive-pressure ventilators for home noninvasive ventilation (NIV) provide physicians with software that records items important for patient monitoring, such as compliance, tidal volume (Vt), and leaks. However, to our knowledge, the validity of this information has not yet been independently assessed.

Methods

Testing was done for seven home ventilators on a bench model adapted to simulate NIV and generate unintentional leaks (ie, other than of the mask exhalation valve). Five levels of leaks were simulated using a computer-driven solenoid valve (0-60 L/min) at different levels of inspiratory pressure (15 and 25 cm H2O) and at a fixed expiratory pressure (5 cm H2O), for a total of 10 conditions. Bench data were compared with results retrieved from ventilator software for leaks and Vt.

Results

For assessing leaks, three of the devices tested were highly reliable, with a small bias (0.3-0.9 L/min), narrow limits of agreement (LA), and high correlations (R2, 0.993-0.997) when comparing ventilator software and bench results; conversely, for four ventilators, bias ranged from −6.0 L/min to −25.9 L/min, exceeding −10 L/min for two devices, with wide LA and lower correlations (R2, 0.70-0.98). Bias for leaks increased markedly with the importance of leaks in three devices. Vt was underestimated by all devices, and bias (range, 66-236 mL) increased with higher insufflation pressures. Only two devices had a bias < 100 mL, with all testing conditions considered.

Conclusions

Physicians monitoring patients who use home ventilation must be aware of differences in the estimation of leaks and Vt by ventilator software. Also, leaks are reported in different ways according to the device used.

Section snippets

Materials and Methods

A panel of home ventilators distributed in Western Europe and equipped with built-in software providing at least monitoring of leaks, RR, and Vt were tested. Seven ventilators were included: Monnal T30 (Airox), Synchrony and Trilogy (Philips Respironics), Ventimotion (Weinmann), Vivo 40 (Breas), and VPAP III ST and VPAP IV ST-A (ResMed). Software brands and the modes of estimation of leaks are summarized in Table 1. Tests were performed between July and September 2009.

Leaks

Figure 2 and Table 2 summarize results regarding leaks. For ventilators F and G, intentional leaks (ie, of mask exhalation valve) are not included in data reported by the ventilator software, and therefore were subtracted from total leaks measured by the bench test to allow comparison between the bench test and software values. With this kept in mind, the threshold of clinical relevance for leaks suggested, arbitrarily, by manufacturers is 24 L/min for devices F and G.8, 21 For other devices,

Discussion

The present study is, to our knowledge, the first to assess the reliability of two important parameters, leaks and Vt, provided by the software of recent home bilevel ventilators by comparing results with objective assessment on a bench test. Results show the following: (1) different devices do not estimate leaks in the same way, that among seven ventilators tested, results provided were calculated in three different ways; (2) the precision of estimation of leaks varied very significantly

Acknowledgments

Author contributions: Mr Contal: contributed to the study design and protocol, recording and analysis of data, and writing and revision of the manuscript.

Ms Vignaux: contributed to the recording and analysis of data and revision of the manuscript.

Dr Combescure: contributed to the analysis of data, statistical analysis, and revision of the manuscript.

Dr Pepin: contributed to the study design and protocol, analysis of data, and writing and revision of the manuscript.

Dr Jolliet: contributed to the

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    Funding/Support: The authors have reported to CHEST that no funding was received for this study.

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

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