Abstract
IntroductionSleeve gastrectomy (SG) has become a widespread treatment option in patients affected by severe obesity. However, studies investigating the impact of the subsequent weight loss on the ventilatory response at rest and during physical exercise are lacking.MethodsThis is an observational study on 46 patients with severe obesity (76% females), comparing parameters of ventilatory function 1 month before and 6 months after SG. Patients were first evaluated by resting spirometry and subsequently with an incremental, maximal cardiopulmonary exercise test (CPET) on treadmill.ResultsThe important weight loss of 26.35 ± 6.17% of body weight (BMI from 43.59 ± 5.30 to 32.27 ± 4.84 kg/m2) after SG was associated with a significant improvement in lung volumes and flows during forced expiration at rest, while resting ventilation and tidal volume were reduced (all p ≤ 0.001). CPET revealed decreased ventilation during incremental exercise (p < 0.001), with a less shallow ventilatory pattern shown by a lower increase of breathing frequency (∆BFrest to ATp = 0.028) and a larger response of tidal volume (∆TVAT to Peakp < 0.001). Furthermore, a concomitant improvement of the calculated dead space ventilation, VE/VCO2 slope and peripheral oxygen saturation was shown (all p ≤ 0.002). Additionally, the increased breathing reserve at peak exercise was associated with a lower absolute oxygen consumption but improved exercise capacity and tolerance (all p < 0.001).ConclusionThe weight loss induced by SG led to less burdensome restrictive limitations of the respiratory system and to a reduction of ventilation at rest and during exercise, possibly explained by an increased ventilatory efficiency and a decrease in oxygen demands.
Highlights
Sleeve gastrectomy (SG) has become a widespread treatment option in patients affected by severe obesity
The effects of bariatric surgery on obesity-related ventilatory disorders, such as obesityhypoventilation syndrome or obstructive sleep apnoea syndrome, should be addressed by future research. This is the first study to investigate the impact of sleeve gastrectomy (SG) on ventilation at rest and during incremental exercise, evaluating respiratory function, breathing pattern/efficiency and the effects on exercise capacity, in a highly selected and homogeneously treated study population of severely obese patients
It is possible to affirm that the massive weight loss during the first 6 months after SG leads to an improvement in respiratory restrictive limitations and in ventilation mechanics that contribute to a more efficient ventilation both at rest and during exercise
Summary
Sleeve gastrectomy (SG) has become a widespread treatment option in patients affected by severe obesity. Adipose tissue accumulation on chest wall, abdomen and in proximity of the upper airways may have an impact on lung function, even in the absence of a specific pulmonary disease This may cause a limitation in thorax and diaphragm mobility, required for appropriate chest wall compliance and ventilatory efficiency [2, 3]. Hyperinflation reduces the efficiency of inspiratory muscles, leading to increased oxygen costs of breathing This shallow and rapid ventilatory pattern may bypass counteracting elastic forces, the relative dead space ventilation increases [2, 4, 8, 9]. All these issues contribute to reducing the ventilatory efficiency during exercise in these patients [4, 10]
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