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Jean-Christian Borel, PhD; Renaud Tamisier, MD, PhD; Patrick Levy, MD, PhD; Jean-Louis Pépin, MD, PhD
Author and Funding Information

From INSERM U 1042, HP2 Laboratory, Faculté de Médecine, Université Joseph Fourier; and CHU, Pôle Rééducation et Physiologie, Hôpital A. Michallon.

Correspondence to: Jean Louis Pépin, MD, PhD, Laboratoire EFCR, CHU de Grenoble, BP217X, 38043 Grenoble cedex 09, France; e-mail: jpepin@chu-grenoble.fr


Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

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


Chest. 2012;142(2):541-542. doi:10.1378/chest.12-0902
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To the Editor:

We appreciate the interest of Dr Murphy and colleagues in our article in CHEST1 on a randomized control study investigating the efficacy of noninvasive ventilation (NIV) on respiratory, sleep, cardiovascular, metabolic, and inflammatory outcomes in obesity hypoventilation syndrome (OHS). We acknowledge that our control group was not submitted to sham-NIV, but had only lifestyle counseling. Indeed, any participation in a clinical research study is likely to improve a patient’s lifestyle. Therefore, patients in both groups may have changed their lifestyle (eg, increased their physical activity). In any case, this cannot mask a specific effect of NIV on cardiovascular and metabolic parameters.

Our study demonstrated that short-term NIV dramatically improves sleep and blood gases but does not alter inflammatory, metabolic, or cardiovascular markers. This suggests a need to address these comorbidities by offering combined treatment modalities. Programs aimed at reducing the detrimental consequences of obesity systematically target an increase in physical activity and a reduction in sedentary behaviors. In their recent work in patients with OHS, Murphy and colleagues2 reported objective improvement in physical activity after 3 months of nocturnal NIV. This elegant study, including patients both in a stable state and in post-acute respiratory failure, compared two ventilatory modes with a randomized control design. Therefore, all patients were exposed to NIV treatment. Thus, it is disputable whether weight loss and physical activity improvements were related to NIV per se or to lifestyle changes associated with inclusion in a clinical research protocol. Moreover, patients placed on NIV during post-acute respiratory failure were likely to have low physical activity at baseline, whereas a dramatic improvement in activity was expected after 3 months of recovery.

Actually, obesity itself promotes limited physical activity and sedentary behavior partly because of exercise-related dyspnea. NIV during exercise training in rehabilitation programs might enhance exercise capacity by reducing the respiratory load in subjects who are morbidly obese.3 Additionally, we have demonstrated that the training of respiratory muscles in subjects who are obese improves dyspnea and exercise capacity.4 We are currently evaluating these tools in rehabilitation programs aimed at reducing cardiometabolic risks in obese subjects,5 in addition to nocturnal NIV. NIV initiation could, thus, be the appropriate starting time for such integrated programs, although the best modalities to improve motivation and adherence have yet to be determined.6 Future studies should not only evaluate the efficacy of combining nocturnal NIV and rehabilitation programs, but also determine the rate of drop-outs and the cost-effectiveness of such combined strategies in OHS treatment.

Borel J-C, Tamisier R, Gonzalez-Bermejo J, et al. Noninvasive ventilation in mild obesity hypoventilation syndrome: a randomized controlled trial. Chest. 2012;141(3):692-702.
 
Murphy PB, Davidson C, Hind MD, et al. Volume targeted versus pressure support non-invasive ventilation in patients with super obesity and chronic respiratory failure: a randomised controlled trial [published online ahead of print March 1, 2012]. Thorax. doi:10.1136/thoraxjnl-2011-201081.
 
Dreher M, Kabitz HJ, Burgardt V, Walterspacher S, Windisch W. Proportional assist ventilation improves exercise capacity in patients with obesity. Respiration. 2010;80(2):106-111.
 
Villiot-Danger JC, Villiot-Danger E, Borel JC, Pépin JL, Wuyam B, Vergès JS. Respiratory muscle endurance training in obese patients. Int J Obes (Lond). 2011;35(5):692-699.
 
National Institutes of Health Clinical CenterNational Institutes of Health Clinical Center. Obese patients with obstructive sleep apnea syndrome (OSAS) and exercise training (OBEX1). NCT01155271 ClinicalTrials.gov.Bethesda, MD: National Institutes of Health; 2010.http://clinicaltrials.gov/ct2/show/NCT01155271. Updated March 13, 2012.
 
Jordan KE, Ali M, Shneerson JM. Attitudes of patients towards a hospital-based rehabilitation service for obesity hypoventilation syndrome. Thorax. 2009;64(11):1007.
 

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References

Borel J-C, Tamisier R, Gonzalez-Bermejo J, et al. Noninvasive ventilation in mild obesity hypoventilation syndrome: a randomized controlled trial. Chest. 2012;141(3):692-702.
 
Murphy PB, Davidson C, Hind MD, et al. Volume targeted versus pressure support non-invasive ventilation in patients with super obesity and chronic respiratory failure: a randomised controlled trial [published online ahead of print March 1, 2012]. Thorax. doi:10.1136/thoraxjnl-2011-201081.
 
Dreher M, Kabitz HJ, Burgardt V, Walterspacher S, Windisch W. Proportional assist ventilation improves exercise capacity in patients with obesity. Respiration. 2010;80(2):106-111.
 
Villiot-Danger JC, Villiot-Danger E, Borel JC, Pépin JL, Wuyam B, Vergès JS. Respiratory muscle endurance training in obese patients. Int J Obes (Lond). 2011;35(5):692-699.
 
National Institutes of Health Clinical CenterNational Institutes of Health Clinical Center. Obese patients with obstructive sleep apnea syndrome (OSAS) and exercise training (OBEX1). NCT01155271 ClinicalTrials.gov.Bethesda, MD: National Institutes of Health; 2010.http://clinicaltrials.gov/ct2/show/NCT01155271. Updated March 13, 2012.
 
Jordan KE, Ali M, Shneerson JM. Attitudes of patients towards a hospital-based rehabilitation service for obesity hypoventilation syndrome. Thorax. 2009;64(11):1007.
 
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