Inspiratory muscle training in patients with bronchial asthma. Inspiratory muscle training in patients with cystic fibrosis. Inspiratory muscle training is ineffective in mechanically ventilated critically ill patients. Inspiratory muscle training improves lung function and exercise capacity in adults with cystic fibrosis.
In patients with asthma, the respiratory muscles have to overcome the increased resistance while they become progressively disadvantaged by hyperinflation. We hypothesized that increasing respiratory muscle strength and endurance with specific inspiratory muscle training (SIMT) would result in improvement in asthma symptoms in patients with asthma. Thirty patients with moderate to severe asthma were recruited into 2 groups; 15 patients received SIMT (group A) and 15 patients were assigned to the control group (group B) and got sham training in a double-blind group-comparative trial. The training was performed using a threshold inspiratory muscle trainer. Subjects of both groups trained five times a week, each session consisted of 1/2-h training, for six months. Inspiratory muscle strength, as expressed by the PImax at RV, increased significantly, from 84.0 +/- 4.3 to 107.0 +/- 4.8 cm H2O (p < 0.0001) and the respiratory muscle endurance, as expressed by the relationship between Pmpeak and PImax from 67.5 +/- 3.1 percent to 93.1 +/- 1.2 percent (p < 0.0001), in patients of group A, but not in patients of group B. This improvement was associated with significant improvements compared with baseline for asthma symptoms (nighttime asthma, p < 0.05; morning tightness, p < 0.05; daytime asthma, p < 0.01; cough, p < 0.005), inhaled B2 usage (p < 0.05), and the number of hospital (p < 0.05) and sick-leave (p < 0.05) days due to asthma. Five patients were able to stop taking oral/IM corticosteroids while on training and one in the placebo group. We conclude that SIMT, for six months, improves the inspiratory muscle strength and endurance, and results in improvement in asthma symptoms, hospitalizations for asthma, emergency department contact, absence from school or work, and medication consumption in patients with asthma. Little information is available about the effects of inspiratory muscle training in patients with cystic fibrosis (CF). In this study the effects of inspiratory-threshold loading in patients with CF on strength and endurance of the inspiratory muscles, pulmonary function, exercise capacity, dyspnoea and fatigue were evaluated. Sixteen patients were assigned to one of two groups using the minimization method: eight patients in the training group and eight patients in the control group. The training was performed using an inspiratory-threshold loading device. Patients were instructed to use the threshold trainer 20 min a day, 5 days a week for 6 weeks. Patients in the training group trained at inspiratory threshold loads up to 40% of maximal static inspiratory pressure (Pimax) and patients in the control group got 'sham' training at a load of 10% of Pimax. No significant differences were found among the two groups in gender, age, weight, height, pulmonary function, exercise capacity, inspiratory-muscle strength and inspiratory-muscle endurance before starting the training programme. Mean (SD) age in the control group was 19 (5.5) years, mean (SD) age in the training group was 17 (5.2) years. Mean FEV1 in both groups was 70% predicted, mean inspiratory-muscle strength in both groups was above 100% predicted. All patients except one, assigned to the training group, completed the programme. After 6 weeks of training, mean inspiratory-muscle endurance (% Pimax) in the control group increased from 50% to 54% (P = 0.197); in the training group mean inspiratory muscle endurance (% Pimax) increased from 49% to 66% (P = 0.003). Statistical analysis showed that the change in inspiratory-muscle endurance (% Pimax) in the training group was significantly higher than in the control group (P = 0.012). After training, in the training group there was a tendency of improvement in Pimax with an increase from 105 to 123% predicted, which just fell short of statistical significance (P = 0.064). After training no significant differences were found in changes from baseline in pulmonary function, exercise capacity, dyspnoea and fatigue. It is concluded that low-intensity inspiratory-threshold loading at 40% of Pimax was sufficient to elicit an increased inspiratory-muscle endurance in patients with CF. Invasive mechanical ventilation is associated with complications, and its abbreviation is desirable. The imbalance between increased workload, decreased inspiratory muscle strength and endurance is an important determinant of ventilator dependence. Low endurance may be present due to respiratory muscle atrophy, critical illness, or steroid use. Specific inspiratory muscle training may increase or preserve endurance. The objective of the study was to test the hypothesis that inspiratory muscle training from the beginning of mechanical ventilation would abbreviate the weaning duration and decrease reintubation rate. As a secondary objective, we described the evolution of inspiratory muscle strength with and without inspiratory muscle training.
                Prospective, randomized clinical trial in an adult clinical-surgical intensive care unit. Twelve patients trained the inspiratory muscles twice a day, and 13 patients did not (control). Training was performed adjusting the sensitivity of the ventilator based on the maximal inspiratory pressure. Patients underwent daily surveillance of the maximal inspiratory pressure.
                The weaning duration (31 +/- 22 hr, control and 23 +/- 11 hr, training group; P = .24) and reintubation rate (5 control and 3 training group; P = .39) were not statistically different. The maximal inspiratory pressure of the control group showed a trend toward a modest increase. In contrast, the training group showed a small decrease (P = .34).
                In acute critically ill patients, inspiratory muscle training from the beginning of mechanical ventilation neither abbreviated the weaning duration, nor decreased the reintubation rate. Inspiratory muscle strength tended to stay constant, along the mechanical ventilation, with or without this specific inspiratory muscle training. To investigate the effects of high-intensity inspiratory muscle training (IMT) on inspiratory muscle function (IMF), diaphragm thickness, lung function, physical work capacity (PWC), and psychosocial status in patients with cystic fibrosis (CF).
                Twenty-nine adult patients with CF were randomly assigned to three groups. Two groups were required to complete an 8-week program of IMT in which the training intensity was set at either 80% of maximal effort (group 1; 9 patients) or 20% of maximal effort (group 2; 10 patients). A third group of patients did not participate in any form of training and acted as a control group (group 3; 10 patients).
                In all patients, baseline and postintervention measures of IMF were determined by maximal inspiratory pressure (Pimax), and sustained Pimax (SPimax); pulmonary function, body composition, and physical activity status were also determined. In addition, diaphragm thickness was measured at functional residual capacity (FRC) and total lung capacity (TLC) [TDIcont], and the diaphragm thickening ratio (TR) was calculated (TR = thickness during Pimax at FRC/mean thickness at FRC). Subjects also completed an incremental cycle ergometer test to exhaustion and two symptom-related questionnaires, prior to and following training.
                Following training, significant increases in Pimax and SPimax (p < 0.05), TDIcont (p < 0.05), TR (p < 0.05), vital capacity (p < 0.05), TLC (p < 0.05), and PWC (p < 0.05) were identified, and decreases in anxiety scores (p < 0.05) and depression scores (p < 0.01) were noted in group 1 patients compared to group 3 patients. Group 2 patients significantly improved Pimax and SPimax (both p < 0.05) only with respect to group 3 patients. No significant differences were observed in group 3 patients.
                An 8-week program of high-intensity IMT resulted in significant benefits for CF patients, which included increased IMF and thickness of the diaphragm (during contraction), improved lung volumes, increased PWC, and improved psychosocial status.
Currently 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.