Influence of Treatment with Continuous Positive Airway Pressure on Respiratory Muscle Function and Physical Fitness in Patients with Obstructive Sleep Apnoea and Overlap Syndrome

Abstract

Introduction: The aim of this study was to evaluate the effect of CPAP treatment on respiratory muscle strength and exercise tolerance in patients with obstructive sleep apnoea (OSA) and overlap syndrome (OS). Material and methods: 9 patients with OSA and 9 patients with OS were studied. Respiratory muscle assessment, 6 minute walking distance (6MWD) and cycloergometry exercise test were performed before and after six month period of CPAP treatment. Results: In OSA group exercise tolerance did not change after the treatment. Mean 6MWD was 571.8 ± 76.6 m before and 554.0 ± 125.5 m after treatment, mean Wmax was 142 ± 41 W before and 139 ± 38 W after treatment. PImax in OSA group did not change significantly, 140.4 ± 32.0 cm H2O before and 155.9 ± 31.5 after treatment (p = 0.14). PEmax improved from 170.5 ± 49.2 cm H2O, to 199.9 ± 27.6 cm H2O (p = 0.067). Handgrip force in OSA group improved from 50.5 ± 16.5 kg to 61.0 ± 17.0 kg (left hand) (p = 0.05) and from 53.3 ± 14.2 to 58.9 ± 15.9 (right hand) (p < 0.05). In OS group exercise tolerance improved by 17% after CPAP treatment from Wmax = 81 ± 33 W before to 95 ± 38 W after. Mean 6MWD was at the same level before (504 ± 144 m) and after treatment (492 ± 108 m). PImax in OS group improved from 89.2 ± 35.7 cm H2O to 106.3 ± 31.4 cm H2O (p < 0.05). PEmax in OS group did not change significantly, 159.9 ± 45.8 cm H2O before and 184.2 ± 45.0 cm H2O after treatment (NS). Handgrip force in OS group improved from 38.1 ± 15.9 kg to 46.9 ± 11.1 kg (left hand) (p < 0.05) and did not change in right hand (44.5 ± 17.7 kg vs. 47.9 ± 10.4 kg) (NS). Data analysis of the whole group (18 pts) showed clear tendency to improve strength of respiratory muscles in patients treated with CPAP. Mean PImax improved from 123 to 133 cm H2O (p = 0.006) and PEmax improved from 168.1 to 192 cm H2O (p = 0.02). Conclusions: CPAP treatment improved strentgh of respiratory and skeletal muscles in patients with OSA and OS and improved exercise tolerance in patients with OS.