Respiratory effects on experimental heat pain and cardiac activity.
OBJECTIVE
Slow deep breathing has been proposed as an effective method to decrease pain. However, experimental studies conducted to validate this claim have not been carried out.


METHODS
We measured thermal pain threshold and tolerance scores from 20 healthy adults during five different conditions, namely, during natural breathing (baseline), slow deep breathing (6 breaths/minute), rapid breathing (16 breaths/minute), distraction (video game), and heart rate (HR) biofeedback. We measured respiration (rate and depth) and HR variability from the electrocardiogram (ECG) output and analyzed the effects of respiration on pain and HR variability using time and frequency domain measures of the ECG.


RESULTS
Compared with baseline, thermal pain threshold was significantly higher during slow deep breathing (P = 0.002), HR biofeedback (P < 0.001), and distraction (P = 0.006), whereas thermal pain tolerance was significantly higher during slow deep breathing (P = 0.003) and HR biofeedback (P < 0.001). Compared with baseline, only slow deep breathing and HR biofeedback conditions had an effect on cardiac activity. These conditions increased the amplitude of vagal cardiac markers (peak-to-valley, P < 0.001) as well as low frequency power (P < 0.001).


CONCLUSIONS
Slow deep breathing and HR biofeedback had analgesic effects and increased vagal cardiac activity. Distraction also produced analgesia; however, these effects were not accompanied by concomitant changes in cardiac activity. This suggests that the neurobiology underlying respiratory-induced analgesia and distraction are different. Clinical implications are discussed, as are the possible cardiorespiratory processes responsible for mediating breathing-induced analgesia.
Chalaye
Philippe
P
Université de Sherbrooke, Faculté de Médecine, Sherbrooke, Québec, Canada.
Goffaux
Philippe
P
Lafrenaye
Sylvie
S
Marchand
Serge
S
D000328:Adult; D000698:Analgesia / Q000379:methods; D001288:Attention / Q000502:physiology; D001676:Biofeedback, Psychology / Q000379:methods / Q000502:physiology*; D001945:Breathing Exercises; D005260:Female; D006329:Heart Conduction System / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D006930:Hyperalgesia / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D008297:Male; D010146:Pain / Q000503:physiopathology / Q000523:psychology; D059408:Pain Management; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000502:physiology / Q000523:psychology; D010775:Photic Stimulation / Q000379:methods; D011603:Psychophysiology; D012143:Respiratory Physiological Phenomena; D016896:Treatment Outcome; D014630:Vagus Nerve / Q000502:physiology; D055815:Young Adult