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Slow recovery from voluntary hyperventilation in panic disorder.
F H Wilhelm1, A L Gerlach, W T Roth
1Department of Psychiatry and Behavioral Sciences, Stanford University, California, USA. fwilhelm@stanford.edu
Psychosomatic Medicine
|August 4, 2001
Summary
Patients with panic disorder (PD) and social phobia (SP) experience more distress during hyperventilation than controls. However, PD patients show slower recovery, indicating distinct physiological responses.
Area of Science:
- Psychiatry
- Psychophysiology
Background:
- Hyperventilation is central to panic disorder (PD) theories, but less so for social phobia (SP).
- Understanding diagnostic differences in responses to hyperventilation is crucial for refining these theories.
Purpose of the Study:
- To compare psychological and physiological responses to voluntary hyperventilation in patients with PD, SP, and healthy controls.
- To investigate diagnosis-specific differences in recovery from hyperventilation-induced hypocapnia.
Main Methods:
- 14 PD patients, 24 SP patients, and 24 controls underwent paced hyperventilation and recovery periods.
- Physiological measures including end-tidal pCO2, heart rate, and skin conductance were recorded.
- Subjective reports of anxiety, dyspnea, and suffocation were collected.
Main Results:
- Both PD and SP patients reported increased anxiety, dyspnea, and suffocation compared to controls during hyperventilation.
- PD patients exhibited slower recovery of physiological measures (pCO2, heart rate, skin conductance) and reported greater awareness of breathing post-hyperventilation.
- Slower recovery in PD was associated with higher sigh breath frequency.
Conclusions:
- Patients with PD and SP experience greater distress from hypocapnia than controls.
- Panic disorder patients demonstrate significantly slower symptomatic and physiological recovery compared to SP patients and controls.
- Findings challenge existing hyperventilation, cognitive-behavioral, and suffocation alarm theories of PD.