Inspiratory muscle training for asthma.

backgroundIn moderate to severe chronic obstructive pulmonary disease there is good evidence of a generalised loss of muscle bulk (including the respiratory muscles). It is possible that similar loss of respiratory muscle strength occur particularly in more severe asthma related in part to the effects of steroid therapy. Thus the respiratory muscle function may well be of relevance in asthma and if dysfunctional, may be a suitable target for training.

objectivesTo evaluate the efficacy of inspiratory muscle training with an external resistive device in patients with asthma. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2002), MEDLINE (January 1966 to March 2002), EMBASE (January 1985 to March 2002), CINAHL (to March 2002) and the UK National Research Register of trials (January 1982 to March 2002) and reference lists of articles. We also searched on line respiratory journals and contacted manufacturers of training devices to obtain trials. SELECTION CRITERIA: All randomised-controlled trials that involved the use of an external inspiratory muscle training device versus a control (sham or no inspiratory training device) were considered for inclusion. DATA COLLECTION AND ANALYSIS: Two reviewers independently selected articles for inclusion, evaluated methodological quality of the studies and abstracted data. MAIN

resultsFive studies were included in the review with four of the studies being produced by the same group. PI(max) (maximum inspiratory pressure) reported in three studies with 76 patients showed significant improvement with inspiratory muscle training when compared to the control group (WMD 23.07 cmH(2)O, 95%CI 15.65 to 30.50). Unfortunately, due to the paucity of included studies and data no other outcome was reported by more than one study. Therefore it is not possible to confirm whether this increase seen with PI(max) translates into any measurable clinical benefit. REVIEWER'S

conclusionsCurrently there is insufficient evidence to suggest that inspiratory muscle training provides any clinical benefit to patients with asthma. Due to the limited availability of studies in this area there is a need for further trials evaluating the efficacy of inspiratory muscle training devices in patients with asthma. These studies should investigate asthmatics with a range of severity. They should investigate clinically relevant outcomes such as lung function, symptoms, exacerbation rate and concomitant medications.