Affiliations: Complejo Hospitalario de Jaén, Jaén, Spain,
Hospital Universitario Son Dureta Palma de Mallorca, Spain,
Hospital Universitario La Paz, Madrid, Spain
Correspondence to: Miguel A. Arias, MD, PhD, Pza de Curtidores No. 2, 4°Dcha, 23007 Jaén, Spain; e-mail: firstname.lastname@example.org
The study by El-Gamal et al (December 2005)1presented evidence of an association between the degree of dyspnea and both an increased ventilatory drive and reduced static lung volumes. Indeed, weight loss was accompanied by improvement in dyspnea and a reduction in respiratory drive measurements. We would like to comment on one other possible mechanism that was not addressed by the authors explaining the frequent presence of dyspnea in obese patients and the improvement in the degree of such symptoms after weight loss. Left ventricular diastolic dysfunction is a frequent cause of dyspnea. It is commonly present in obese subjects and is correlated with increasing body mass index.2In obese subjects, weight loss produces an improvement in left ventricular diastolic function that is linked to weight loss-related decreases in left ventricular mass and beneficial alterations in left ventricular loading conditions.3On the other hand, the authors did not perform polysomnography to rule out obstructive sleep apnea or other sleep disorders, as they acknowledge in the “Discussion” section of their article. It is well-recognized that the vast majority of sleep apnea patients are undiagnosed, and that obstructive sleep apnea is a very common condition affecting obese subjects. This sleep-related disordered breathing has also been independently associated with left ventricular diastolic dysfunction4and reduced cardiac response to exercise.5 Weight loss in obese obstructive sleep apnea patients is coupled with an improvement in sleep disorder severity, and the reduction of apneic events has also been associated with subsequent improvement in left ventricular diastolic function and hemodynamic response to exercise.4–5
In view of the aforementioned comments, it would be helpful for El-Gamal et al1 to provide data on cardiac function and structure for the patients studied to more precisely understand the possible factors playing a role in the presence of dyspnea and its improvement after weight loss.
Drs. Arias, Alonso-Fernández, and García-Río have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.
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