Do blood phobia patients hyperventilate during exposure by breathing faster, deeper, or both?
BACKGROUND
Recently we found that patients with blood-injection-injury (BII) phobia tend to hyperventilate when exposed to feared stimuli. Hyperventilation results from increases in minute ventilation above levels required by metabolic demand and can result from increases in either frequency or depth of breathing, or a combination of both.


METHODS
In order to determine which of these factors contributed most to hyperventilation in BII phobia we analyzed breathing patterns of BII phobia patients (N=12) and non-anxious controls (N=14), recorded with respiratory inductance plethysmography. Participants viewed ten film clips of either an emotionally positive, negative, or neutral quality, as well as surgery and asthma-relevant clips. During five film clips (one from each category) they also tensed their leg muscles.


RESULTS
Minute ventilation was markedly increased in blood phobia patients compared to other groups during surgery films. Also, tidal volume and irregularity of tidal volume showed strong increases, while respiration rate was not affected. Leg muscle tension increased ventilation in general but far below the extent brought about by hyperventilation in BII phobia. Patients who were breathing deeper during exposure reported stronger symptoms of dizziness, light-headedness and faintness. In general, patients showed a higher rate of spontaneous sighs throughout all film presentations, but not at baseline.


CONCLUSIONS
Thus, hyperventilation in blood phobia is produced by excessively deep and irregular breathing and may contribute to fainting responses. Behavioral interventions for BII phobia could benefit from attention to this aspect of dysfunctional breathing.
Ritz
Thomas
T
Department of Psychology, Southern Methodist University, Dallas, Texas 75205, USA. tritz@smu.edu
Wilhelm
Frank H
FH
Meuret
Alicia E
AE
Gerlach
Alexander L
AL
Roth
Walton T
WT
D000328:Adult; D001143:Arousal; D001769:Blood; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000523:psychology*; D007267:Injections / Q000523:psychology; D008297:Male; D008875:Middle Aged; D010698:Phobic Disorders / Q000523:psychology*; D010993:Plethysmography, Whole Body; D012119:Respiration; D013575:Syncope / Q000523:psychology; D014947:Wounds and Injuries / Q000523:psychology; D055815:Young Adult