Paroxetine Decreases Respiratory Irregularity of Linear and Nonlinear Measures of Respiration in Patients with Panic Disorder

Previous studies indicate that serotonin reuptake inhibitors do not appear to have serious cardiac side effects. However, the effects of these agents on respiratory measures have not been studied in detail. Several studies indicate that patients with anxiety exhibit irregular breathing patterns as measured by tidal volume and respiratory rate. In this study, we evaluated the effects of a serotonin reuptake inhibitor, paroxetine, on respiratory variability in patients with panic disorder (n = 13), using linear and nonlinear measures of regularity, approximate entropy (APEN) and a measure of chaos, the largest Lyapunov exponent (LLE), with pre- and posttreatment lung volume time series (256 s long sampled at 4 Hz). Our results show that paroxetine significantly decreases some of the linear measures of variability and supine APEN and standing LLE of lung volume series after successful treatment. The implications of these findings on respiratory and cardiovascular function have been discussed.