Hyperventilation in panic disorder and asthma: empirical evidence and clinical strategies

Abstract

Sustained or spontaneous hyperventilation has been associated with a variety of physical symptoms and has been linked to a number of organic illnesses and mental disorders. Theories of panic disorder hold that hyperventilation either produces feared symptoms of hypocapnia or protects against feared suffocation symptoms of hypercapnia. Although the evidence for both theories is inconclusive, findings from observational, experimental, and therapeutic studies suggest an important role of low carbon dioxide (CO2) levels in this disorder. Similarly, hypocapnia and associated hyperpnia are linked to bronchoconstriction, symptom exacerbation, and lower quality of life in patients with asthma. Raising CO2 levels by means of therapeutic capnometry has proven beneficial effects in both disorders, and the reversing of hyperventilation has emerged as a potent mediator for reductions in panic symptom severity and treatment success.

Figure 1

Changes in PCO₂ and respiration rate during a standardized voluntary hyperventilation test. Upper line represents end-tidal PCO₂ and lower line represents respiration.

Figure 2

Illustration of the ambulatory set-up for 24-h monitoring with panic disorder patients. Capnometry device [9] with attached nasal cannula [1], sound sensor [2], EKG [3], thoracic and abdominal plethysmography bands [4], accelerometers [5], external and finger temperature sensors [6], electrodermal activity [7].