CT-guided transthoracic lung biopsy: predictive factors of pneumothorax.

association has been described with similar results and could be due to a combination of the effects of obesity and diffuse airway obstruction. Obesity is known to be a major risk factor for OSA linked with increased neck circumference and amounts of peripharyngeal fat, which could narrow and compress the upper airway; obesity may also play a role by reducing lung volumes. Obesity affects ERV by decreasing FRC, and ERV may also be reduced with an increase in residual volume (RV) that occurs, not exclusively, but particularly in the obese, due to premature closure of the small peripheral airways. We found that the absolute effect of the correlation of ERV with obstructive events was similar to the effect of BMI, but ERV remained influential independently of all confounders such as BMI. The reduction in end-expiratory lung volumes, which are accentuated in sleep, may lead to a reduction in tracheal traction on the pharynx and so increasing its collapsibility. Conversely, increases in lung volumes have been shown to increase tracheal traction with stabilization of the upper airway during inspiration, and in OSA patients, they have been shown to decrease positive airway pressure requirements and OSA severity, suggesting improvements in pharyngeal collapsibility. Although this relationship seems unequivocal, as shown in our study, more research is needed in order to define more precisely which end-expiratory volume -ERV, FRC or even RV -plays the major role and how it influences the occurrence of obstructive events during sleep. References