Pursed lips breathing: Are we closer to understanding who might benefit?

It is pleasing to see increased research activity that focuses on therapeutic management of dyspnoea and, in particular, greater recognition of the important role that breathing techniques can provide in the amelioration of symptoms associated with Chronic Obstructive Pulmonary Disease (COPD). For many years, the concept of breathing exercises has been poorly understood and, therefore, treatments underutilised. Pursed lip breathing (PLB) sits within that poorly defined toolbox termed ‘breathing exercises’. Traditionally, breathing exercises are insufficiently described, the terminology used is at best, arbitrary, and frequently the same name is given to different interventions. Generally, there is little attempt to standardise the therapy delivered or the breathing technique performed. The American Thoracic Society guidelines describe the technique of PLB as involving ‘a nasal inspiration followed by expiratory blowing against partially closed lips, avoiding forceful exhalation’. Bhatt et al. in the article published in this edition of Chronic Respiratory Disease ‘Volitional pursed lips breathing in stable COPD patients improves exercise’ make the further distinction that ‘exhalation should continue slowly over 4 to 6 seconds without cheek puffing or forced exhalation’. This description of PLB enables better standardisation of a technique that has been the focus of debate for many years. The primary contention surrounding PLB is not so much whether it is effective; over a decade ago, there was sufficient evidence to say that PLB reduces respiratory rate, minute ventilation, and carbon dioxide level; increases tidal volume, arterial oxygen pressure, and oxygen saturation; and we ourselves showed positive effects on respiratory rate and time to recovery post exercise. As such, many people with COPD spontaneously adopt this technique; the contention around PLB concerns its use in people with COPD who do not naturally perform the technique and whether reductions in respiratory rate and oxygen saturation translate into improved exercise tolerance and perception of dyspnoea. Bhatt’s article addresses this question nicely. Giving patients adequate training in the technique and excluding any subjects who used it automatically (none did) they performed, in a randomised order, two 6-minute walk tests (6MWT), including an earlier practice test, with and without the use of PLB. These were patients with severe lung impairment (mean FEV1 38% predicted). Interestingly, the population was, on average, relatively young (mean age 53 years) with a fairly short duration of symptoms for such impairment suggesting that these may be patients who have not had sufficient time, or experience, to develop additional coping strategies such as PLB. One memorable patient from our clinic, when asked why he used PLB, told us it was because he was taught it by another patient in the rehabilitation class and finding it helpful he had continued to use it. Clinically we see patients adopting PLB during periods of acute illness, and the use of PLB at rest is an indicator of increased work of breathing. In Bhatt’s article, use of PLB in this group of patients with severe COPD, unaccustomed to the technique, resulted in a small but statistically significant improvement in a 6-minutewalk distance (6MWD); the improvement however just failed to reach the lower confidence interval of the minimally clinically important difference in 6MWD. Whether these effects are accompanied by improvements in the perception of dyspnoea are as yet unknown. Furthermore, since oxygen saturation was not recorded, we cannot make a comment on the role of PLB in patients who show exercise desaturation. In this study, as in others, there was no consistent