Panic disorder, the ventilatory response to carbon dioxide and respiratory variables.

Increased sensitivity of the central carbon dioxide chemoreceptors to carbon dioxide has been hypothesized as a biologic determinant of panic attacks in panic disorder and on voluntary inhalation of carbon dioxide mixtures. The ventilatory response to carbon dioxide, a measure of sensitivity, was assessed in 12 patients with panic disorder and 12 matched normal controls. While mean sensitivity was similar for both groups, for the panic disorder patients, mean sensitivity due to the tidal volume component was significantly less than for the normal controls, and mean sensitivity due to the frequency component was significantly greater than for the normal controls. The interpretation of the effects of carbon dioxide inhalation as a neurobiologic and behavioral probe may be enhanced if the components of the ventilatory response are examined separately.