Effects of breathing training on voluntary hypo- and hyperventilation in patients with panic disorder and episodic anxiety.

Anxiety disorders are associated with respiratory abnormalities. Breathing training (BT) aimed at reversing these abnormalities may also alter the anxiogenic effects of biological challenges. Forty-five Panic Disorder (PD) patients, 39 Episodic Anxiety patients, and 20 non-anxious controls underwent voluntary hypoventilation and hyperventilation tests twice while psychophysiological measures were recorded. Patients were randomized to one of two BT therapies (Lowering vs. Raising pCO(2)) or to a waitlist. Before treatment panic patients had higher respiration rates and more tidal volume instability and sighing at rest than did non-anxious controls. After the Lowering therapy, patients had lower pCO(2) during testing. However, neither reactivity nor recovery to either test differed between patients and controls, or were affected by treatment. Although the two treatments had their intended opposite effects on baseline pCO(2), other physiological measures were not affected. We conclude that baseline respiratory abnormalities are somewhat specific to PD, but that previously reported greater reactivity and slower recovery to respiratory challenges may be absent.