March 17, 2009 (Santa Ana Pueblo, New Mexico) — For individuals with blood-injection-injury (BII) phobia, a novel biobehavioral approach aimed at regulating breathing may lessen anxiety, new research suggests.
In a study presented at the Anxiety Disorders Association of America 2009 Annual Conference, investigators from Southern Methodist University, in Dallas, Texas, reported that breathing retraining treatment (BRT) was just as effective as standard treatment with applied tension (AT) for reducing anxiety in people with BII phobia, and both treatments were more effective than relaxation.
According to lead author Erica S. Ayala, BII phobia is common, with a reported prevalence of 3.5%, and is associated with a high cost to individuals and society because patients often avoid preventive and medical care due to their fears. Few studies have been done on potential treatments for the disorder, and understanding of the underlying physiology remains poor.
Given that up to 75% of people with BII phobia report BII-related syncope and that hyperventilation, in which cerebral vessels constrict, may play a role in fainting, Ayala and colleagues conducted the study to see whether hyperventilation contributes to phobic response and, if so, whether regulating breathing may reduce anxiety.
To test this, investigators replicated hyperventilation and compared the ability of BRT to reduce hyperventilation vs AT or relaxation. They also compared the impact of the 3 treatments in reducing anxiety.
Of the 60 patients enrolled in the trial, 20 were treated with BRT, 20 with AT, and 20 with relaxation. In each of the treatment groups, 9 reported a history of fainting, 5 reported almost fainting, and 6 reported no history of fainting.
To replicate hyperventilation, participants were asked to view film clips in 2 separate sessions. During session 1, the participants viewed 5 films to elicit different emotions (happiness, sadness, anger, disgust, and neutral) as well as 1 surgical film to elicit the BII response.
In session 2, the participants viewed a separate set of emotion-related films plus 2 BII-relevant films and were asked to practice the intervention techniques during film viewing and provide feedback.
Using capnography to measure end-tidal partial pressure of carbon dioxide (pCO2) respiration rate, the investigators found that during session 1, the mean pCO2 dropped to 33.4 mm Hg during the surgery film, compared with 34.4 to 35 mm Hg during the other films, and dropped again for 1-minute recoveries to 32.1 mm Hg for surgery, compared with 34.4 to 35.3 mm Hg during the other films.
The mean pCO2 significantly increased from session 1 to session 2 only in the patients treated with BRT, suggesting that only BRT reduced hyperventilation.
Based on self-reported ratings of anxiety, the study also showed that anxiety was significantly reduced in patients from session 1 to session 2, with a trend toward less improvement in anxiety reduction with the relaxation technique compared with BRT or AT.
Although patients treated with AT reported significantly more success in performing this technique compared with the other techniques, BRT and AT were reported as significantly more helpful in reducing the phobic response compared with relaxation.
The study did not show any significant differences in overt fainting among any of the treatments. However, the researchers did find that 25% of patients treated with relaxation during the surgery film terminated watching the film early, compared with 5% of the patients treated with BRT and 10% of those treated with AT (10%).
Commenting on the study, Walton Roth, MD, from the Stanford School of Medicine, in California, questioned the proposed mechanism of hyperventilation and fainting.
"Ordinarily, when people pass out, that is not hyperventilation from a medical point of view; it is usually thought that fainting of the kind that leads to falling to the floor has to do with a decrease in blood pressure that is mediated by a slower heart rate," he said. Dr. Roth added that he would have expected to see the study measure the effect of the therapies on blood pressure.
The authors are in the process of analyzing these data.
Anxiety Disorders Association of America 2009 Annual Conference: Poster 103C. Presented March 13, 2009.