RESUMEN
Background: The effects of expiratory muscle strength training (EMST) has not yet been investigated in MSA patients. Objective: The primary objective was to test the effects of EMST on expiratory muscle strength and voluntary peak cough flow (vPCF) in patients with multiple system atrophy (MSA). The secondary objective was to assess the suitability of the pulmonary dysfunction index as a tool for identifying MSA patients with expiratory muscle weakness and reduced voluntary peak cough flow. Methods: This was an open label, non-controlled study, with an 8-week intensive home-based EMST protocol. The outcome measures included: maximal expiratory pressure (MEP) and vPCF. The sensitivity and specificity of the index of pulmonary dysfunction in the respiratory diagnostic process were assessed using receiver operating characteristic (ROC) analysis. Results: Fifteen MSA patients were enrolled in the study. Twelve MSA patients completed the training period. After the training period, MEP significantly increased (P = 0.006). Differences in vPCF were not significant (P = 0.845). ROC analysis indicated that the overall respiratory diagnostic accuracy of the index of pulmonary dysfunction had an outstanding capability to detect patients at risk of less effective coughing and an acceptable capability of detecting patients with decreased expiratory muscle strength. Conclusions: These findings indicate non-significant differences in vPCF after 8 weeks of EMST. The index of pulmonary dysfunction appears to be a promising prognostic screening tool for identifying altered cough efficacy in MSA patients. Test cut-offs may be used to select an appropriate respiratory physiotherapy technique.
RESUMEN
BACKGROUND: The efficacy of expiratory muscle strength training (EMST) in patients with multiple sclerosis (MS) is controversial. The current study's primary objective was to test the effects of a progressive and intensive 12 week home based EMST program on expiratory muscle strength and voluntary cough strength. The secondary objective was to determine the retention of EMST benefits. METHODS: Thirty-five severely disabled MS patients (relapsing-remitting MS, n = 15; primary progressive MS, n = 5; secondary progressive MS, n = 15) with Expanded Disability Status Scale (EDSS) 5.0 - 7.0 were included in the study. Within 36 weeks, patients completed 12 weeks of a non-training period, 12 weeks of EMST and 12 weeks of a detraining period. Maximal expiratory pressure (PEmax) and voluntary peak cough flow (vPCF) were assessed 4 times: at week 0 (baseline), week 12 (pre-training), week 24 (post-training), and week 36 (post-detraining). MS patients included in the study were compared to age- and sex-matched healthy subjects. In the healthy controls, the PEmax and vPCF were assessed once to obtain normative data. RESULTS: Twenty-six patients completed the training period (mean age 52.7 ± 10.2, EDSS 5.9 ± 0.6) and were compared to 26 sex- and age-matched healthy subjects (mean age 53.5 ± 5.8). Patients with MS had a lower PEmax (p = 0.002) and vPCF (p = 0.022) at baseline than the healthy control group. In training period, the PEmax and vPCF increased (p = 0.0000; effect size: d = 0.94 and p = 0.0036; d = 0.57 respectively) in comparison with the non-training period (p = 0.0692; d = -0.36 and p = 0.5810; d = 0.11 respectively). Following the 12 weeks detraining period, the PEmax and vPCF declined but remained 16.7% and 5.5% respectively above the pre-training values. No differences were observed in the PEmax and vPCF between the MS group at the post-training and post-detraining timepoint and the healthy control group normative values. CONCLUSIONS: EMST improves expiratory muscle strength and voluntary cough strength in severely disabled MS patients.