Chest
Volume 143, Issue 1, January 2013, Pages 37-46
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Original Research
Sleep Disorders
Impact of Different Backup Respiratory Rates on the Efficacy of Noninvasive Positive Pressure Ventilation in Obesity Hypoventilation Syndrome: A Randomized Trial

https://doi.org/10.1378/chest.11-2848Get rights and content

Background

Unintentional leaks, patient-ventilatory asynchrony, and obstructive or central events (either residual or induced by noninvasive positive pressure ventilation [NPPV]) occur in patients treated with NPPV, but the impact of ventilator settings on these disturbances has been little explored. The objective of this study was to investigate the impact of backup respiratory rate (BURR) settings on the efficacy of ventilation, sleep structure, subjective sleep quality, and respiratory events in a group of patients with obesity hypoventilation syndrome (OHS).

Methods

Ten stable patients with OHS treated with long-term nocturnal NPPV underwent polysomnographic recordings and transcutaneous capnography on 3 consecutive nights with three different settings for BURR in random order: spontaneous (S) mode, low BURR, and high BURR. No other ventilator parameter was modified.

Results

The S mode was associated with the occurrence of a highly significant increase in respiratory events, mainly of central and mixed origin, when compared with both spontaneous/timed (S/T) modes. Accordingly, the oxygen desaturation index was significantly higher in the S mode than in either of the S/T modes. The results of nocturnal transcutaneous Pco2 (Ptcco2) (mean value and time spent with Ptcco2 > 50 mm Hg) were similar over the three consecutive nocturnal recordings. The quality of sleep was perceived as slightly better, and the number of perceived arousals as lower with the low- vs high-BURR (S/T) mode.

Conclusions

In a homogenous group of patients treated with long-term NPPV for obesity-hypoventilation, changing BURR from an S/T mode with a high or low BURR to an S mode was associated with the occurrence of a highly significant increase in respiratory events, of mainly central and mixed origin.

Section snippets

Patients

Patients with OHS treated with long-term nocturnal NPPV, in stable clinical condition, and followed by the Division of Pulmonary Diseases of Geneva University Hospital were included in the study. OHS was defined as the association of morbid obesity (BMI > 30 kg/m2) and daytime hypercapnia without any other obstructive or restrictive pulmonary pathology.19 Exclusion criteria were age < 18 years, FEV1/FVC < 70%, history of an acute episode of cardiac and/or respiratory failure within the past 3

Results

Figure 2 shows the flowchart of patient inclusion. All 10 patients included (eight men) had been placed under NPPV after at least one episode of acute hypercapnic respiratory failure. Their characteristics and usual ventilator settings are summarized in Table 1. All had associated severe obstructive sleep apnea-hypopnea syndrome. Nine patients used a facial mask. Four patients used supplemental oxygen.

Based on an analysis of ventilator software over the 2 preceding weeks, the low median BURR

Discussion

This is, to our knowledge, the first study to analyze the impact on sleep structure and treatment efficacy of changes in BURR performed in a random order in a group of patients familiar with NPPV, all suffering from OHS and treated with the same bilevel NPPV device. No other ventilator setting was modified. Results show highly significant differences between the S mode and both S/T modes in terms of respiratory events, and, more specifically, of central and mixed events. Both the occurrence of

Conclusions

In summary, in a short-term trial of patients treated with long-term NPPV for obesity-hypoventilation, using the same NPPV device, changing BURR from an S/T mode with a high or low BURR to an S mode was associated with a highly significant increase in respiratory events, mainly central and mixed events. All respiratory events were lowest under the high-BURR S/T mode. Although our sample size precludes any definite conclusions as to the possible impact of these observations on sleep structure,

Acknowledgments

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

Dr Adler: contributed to the recording and analysis of data and revision of the manuscript.

Dr Borel: contributed to the recording and analysis of data and writing and revision of the manuscript.

Mr Espa: contributed to the recording and analysis of data and writing and revision of the manuscript.

Dr Perrig: contributed to the writing and

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  • Cited by (0)

    Funding/Support: This study was supported by an unrestricted grant from the Pulmonary League of Geneva (www.lpge.ch), the Swiss Society of Pulmonology, and the Lancardis Foundation.

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

    *

    Drs Rodenstein, Pépin, and Janssens are from the SomnoNIV group

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