The use of mouth taping in people with asthma: a pilot study examining the effects on end-tidal carbon dioxide levels

ObjectivesThe use of mouth taping, to encourage nose breathing, is currently being recommended by some Buteyko practitioners, but its effects on physiology are unknown. This preliminary study aimed to investigate the effects of mouth taping on end-tidal carbon dioxide (ETCO2).DesignPreliminary study with an experimental single group repeated measures design.SettingResearch laboratory, university campus.ParticipantsNine university students and staff with mild stable asthma.InterventionsPhysiological data were recorded before and during two experimental breathing conditions: oral breathing and nasal breathing (encouraged by mouth taping), carried out on two separate occasions 5–14 days apart. Between visits, participants familiarised themselves with the mouth taping technique.Outcome measuresPrimary outcome was ETCO2. Secondary outcomes were respiratory rate, pulse rate, oxygen saturation and lung function.ResultsThere was an increase in ETCO2 from baseline during both breathing conditions. The mean ETCO2 for oral breathing was 4.4 kPa versus 4.7 kPa for nasal breathing, with mean difference of 0.3 kPa (95% confidence interval −0.2 to 0.8 kPa). It was also found that ETCO2 increased more in ‘natural’ oral breathers than ‘natural’ nasal breathers.ConclusionsThe results of this pilot study provide data to power a larger study and suggest ETCO2 may be increased in people with asthma during nasal breathing, particularly in those who normally primarily breathe through the mouth. The methodology was found to be acceptable to this sample of people with mild asthma.