Applied Psychophysiology and Biofeedback

, Volume 34, Issue 1, pp 1-6

First online:

Changes in pCO2, Symptoms, and Lung Function of Asthma Patients During Capnometry-assisted Breathing Training

  • Thomas RitzAffiliated withDepartment of Psychology, Southern Methodist University Email author 
  • , Alicia E. MeuretAffiliated withDepartment of Psychology, Southern Methodist University
  • , Frank H. WilhelmAffiliated withUniversity of Basel
  • , Walton T. RothAffiliated withStanford University School of Medicine and the VA Palo Alto Health Care System

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In a recent pilot study with asthma patients we demonstrated beneficial outcomes of a breathing training using capnometry biofeedback and paced breathing assistance to increase pCO2 levels and reduce hyperventilation. Here we explored the time course changes in pCO2, respiration rate, symptoms and lung function across treatment weeks, in order to determine how long training needs to continue. We analyzed in eight asthma patients whether gains in pCO2 and reductions in respiration rate achieved in home exercises with paced breathing tapes followed a linear trend across the 4-week treatment period. We also explored the extent to which gains at home were manifest in weekly training sessions in the clinic, in terms of improvement in symptoms and spirometric lung function. The increases in pCO2 and respiration rate were linear across treatment weeks for home exercises. Similar increases were seen for in-session measurements, together with gradual decreases in symptoms from week to week. Basal lung function remained stable throughout treatment. With our current protocol of paced breathing and capnometry-assisted biofeedback at least 4 weeks are needed to achieve a normalization of pCO2 levels and reduction in symptoms in asthma patients.


Asthma Hyperventilation pCO2 Biofeedback Asthma symptoms