PATTERN OF LUNG-VOLUMES IN PATIENTS WITH SIGHING BREATHING

Background-Sighing breathing is observed in subjects suffering from an xiety with no apparent organic disease. Methods-Lung volumes and expir atory flow rates were measured in 12 patients with a sighing pattern o f breathing and in 10 normal subjects matched for age, gender, and ant hropometric data. In both groups the measurements were made by spirogr aphic and plethysmographic techniques. In normal subjects functional r esidual capacity (FRC) and residual volume (RV) were measured during n ormal breathing and again during simulated sighing breathing to exclud e technical artifacts resulting from hyperventilation during measureme nt by the helium closed circuit method. Results-Patients with a sighin g pattern of breathing had a normal total lung capacity (TLC) but sign ificantly different partitioning of lung compartments compared with no rmal subjects. The vital capacity (VC) was lower when measured by both spirographic and plethysmographic methods and RV was higher. The forc ed expiratory volume in one second (FEV1) was also lower in patients w ith sighing breathing. The FEV1/VC and the maximal expiratory flow rat es at 50% and at 25% of the forced vital capacity (V50 and V25) were n ormal and similar in both groups. In normal subjects there were no dif ferences in RV when measured during quiet or simulated sighing breathi ng. Conclusions-Subjects with sighing breathing have a normal TLC with a higher RV and lower VC than normal subjects. There was no obvious p hysiological or anatomical explanation for this pattern.