Abstract
Breathing at low pulmonary volumes is one of the several respiratory factors that distinguish obesity and contribute to limit the ventilator constraint on exercise capacity in these patients.
In order to investigate if obese adolescents are characterized by a specific pattern of adaptation of their ventilator pump, 12 male patients (age: 16±1 [x±standard deviation] years, body mass index: 37±5 Kgcm-2) were evaluated during incremental exercise (increments of 20W/minute until the limit of tolerance) on a cycle ergometer. Total and compartmental chest wall volumes were measured by opto-electronic plethysmography during rest and exercise.
The progressive increase in tidal volume was achieved by a progressive increase of end-inspiratory chest wall volume while end-expiratory chest wall volume significantly decreased only at maximal workload.
End-expiratory abdominal and ribcage volumes showed an opposite behaviour. The former significantly decreased while the latter increased with time. End-inspiratory ribcage expansion augmented during exercise (figure 1).
Our results suggest that dynamic ribcage hyperinflation occurs in obese adolescent during incremental exercise. It seems that a ventilatory adaptation oriented toward higher ribcage operating volume is adopted to try to benefit from breathing at higher lung volumes and to exploit the exercise-induced lung volume recruitment where these patients maybe meet a better thoracic compliance.
- © 2014 ERS
