Stress-induced respiratory pattern changes in asthma

Psychosomatic Medicine, 07/08/2011

Ritz T et al. – Expiratory lengthening and variable tidal volumes are characteristic for individuals with asthma during psychosocial stress. The function and possible association of these changes with symptom exacerbations require further study.

Methods

  • Studied respiration during resting conditions and an acute psychosocial stressor (a free speech and mental arithmetic task) in participants with asthma (n = 20) and healthy controls (n = 19)
  • Respiratory pattern was recorded with respiratory inductance plethysmography
  • Partial pressure of end–tidal carbon dioxide (PCO2) measured with capnometry before and after stress

Results

  • Overall minute ventilation was higher in asthma (mean [standard deviation] = 9.0 [4.0] L versus 6.8 [4.1] L, p < .05), but levels of the PCO2 were comparable (34.6 [3.5] mm Hg versus 35.0 [3.7] mm Hg, p = .667) to healthy controls during prestress and poststress phases
  • Participants with asthma also showed a significant lengthening of inspiration, expiration, and the total respiratory cycle during stress compared with healthy controls (p < .05)
  • During stress tasks, all participants showed marked increases in tidal volume, inspiratory flow, minute ventilation, tidal volume instability, ribcage contribution to tidal volume, and ribcage–abdominal asynchrony
  • Significant increase in tidal volume instability and tendency toward lengthening of expiration and total respiratory cycle were observed in quiet–sitting periods at prestress to poststress in asthma

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