Targeting pCO2 in Asthma: Pilot Evaluation of a Capnometry-Assisted Breathing Training

Abstract

Objectives: This pilot study aimed to evaluate the feasibility and potential benefits of a novel biofeedback breathing training for achieving sustained increases in pCO2 levels.Methods: Twelve asthma patients were randomly assigned to an immediate 4-week treatment group or waiting list control. Patients were instructed to modify their respiration in order to change levels of end-tidal pCO2 using a hand-held capnometer. Treatment outcome was assessed in frequency and distress of symptoms, asthma control, lung function, and variability of peak expiratory flow (PEF).Results: We found stable increases in pCO2 and reductions in respiration rate during treatment and 2-month follow-up. Mean pCO2 levels rose from a hypocapnic to a normocapnic range at follow-up. Frequency and distress of symptoms was reduced and reported asthma control increased. In addition, mean PEF variability decreased significantly in the treatment group.Conclusions: Our pilot intervention provided evidence for the feasibility of pCO2-biofeedback training in asthma patients.Response to Reviewers: Dear Dr. Gevirtz, Thank you for the latest comments on our manuscript "Targeting PCO2 in asthma: Pilot-evaluation of a capnometry-assisted breathing training" (APBI55). We have now amended the manuscript by following the reviewrs suggestions in the remaining details. The amended passages are marked in yellow.Thank you for the opportunity to have our work reviewed for your journal. We are excited that it has generated sufficient interest among our reviewers and look forward to seeing it in press. Please let us know if you need more information or materials.

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

“…Across sessions, basal pCO 2 levels increased by more than 4 mmHg, bringing patients from a hypocapnic into a normocapnic range. In addition, weekly asthma symptoms declined steadily across weeks, which is in line with our earlier analysis that focused on changes from pre-to post-treatment and follow-up (Meuret et al 2007). Thus, our findings confirm the need for the full 4-week course of pCO 2 -biofeedback assisted home exercises to obtain the full benefit of the training.…”

“…Because these baseline levels were averaged across all daily exercises, they included a training gain already in the first week as compared to the initial session, as well as a training ''deficit'' in the fourth week compared with the final session. However, given the demonstrated stable levels of pCO 2 and asthma outcome improvement throughout 2-month follow-up (Meuret et al 2007), adding further training sessions or home exercise weeks might turn out be an unnecessary burden and expense.…”

“…Results of our pilot study with asthmatic patients showed substantial increases of pCO 2 across treatment and 2-months followup, together with increases in asthma control and reductions in symptoms and variability of lung function. Basal lung function remained unaffected by the intervention (Meuret et al 2007).…”

“…Methods of the study were presented in detail in our earlier publication (Meuret et al 2007). In short, the present analysis is based on eight asthma patients (six females; mean age = 43.5 years, SD = 11.0) who were assigned randomly to the immediate treatment group.…”

“…This motivated us to adapt and test a capnometry-biofeedback assisted breathing training for patients with asthma (Meuret et al 2007) that had been applied before in panic patients (Meuret et al 2001(Meuret et al , 2004, where it was effective both in reducing pCO 2 levels and panic symptoms (Meuret et al 2008). The training comprised five weekly 1-h therapist-guided training sessions along with home work exercises performed twice-daily home using a portable capnometry device.…”