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Voluntary breath holding in panic and generalized anxiety disorders
W T Roth1, F H Wilhelm, W Trabert
1Department of Psychiatry and Behavioral Sciences, Stanford University, California, USA. wtroth@stanford.edu
Objective:
Because breath holding causes arterial pCO2 to increase, we used it to test the hypothesis that in panic disorder (PD) a biological suffocation monitor is pathologically sensitive.
Method:
Nineteen patients with PD, 17 with generalized anxiety disorder (GAD), and 22 normal controls took deep breaths on signal and held them until a release signal was given 30 seconds later. This was repeated 12 times separated by 60-second normal breathing periods.
Results:
PD patients reported having had in the past more symptoms of shortness of breath when anxious, and more frequent frightening suffocation experiences than the other groups. However, increases in self-rated anxiety between periods of normal breathing and periods of breath holding were similar in all three groups. Skin conductance, blood pressure, and T-wave amplitude reactions to breath holdings were also similar, but heart rate acceleration upon taking a deep breath was greater in GAD patients. Before and after individual breath holdings, end-tidal pCO2 was lower in PD patients than in normal controls; GAD patients were intermediate. Inspiratory flow rate did not differ between groups.
Conclusions:
Our physiological results provide no direct support for an overly sensitive suffocation alarm system in PD. Lower pCO2 may be due to anxiety causing hyperventilation in patients prone to panic.