Résumé :
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Rationale : Patients with restrictive disorders and hypoventilation benefit from nocturnal Non-invasive Ventilation (NIV). If they have reduction of exercise tolerance ambulatory oxygen is normally prescribed. However may also benefit from NIV. Objectives : Describe and analyze the efficacy of mouthpiece intermittent volume ventilation (MIVV) during walking in the improvement of the six-minute walking test parameters. Methods : Seven (six female) patients (mean age of 58 ± 13 years)with walking ability were included (4 with severe scoliosis and 3 with neuromuscular disease). Two patients were excluded from the study, one for inability to deal with MIVV, and the other because of osteoarticular pathology. The FVC was 814 ± 443 ml and all patients were hypercapnic (53 ± 10 mmHg) at home nocturnal NIV initiation (mean duration 70 ± 53 months). Due to clinical deterioration continuous NIV was started (daytime mouthpiece and nocturnal nasal mask). Every patient was evaluated by the six-minute walking test (6M) with and without MIVV (without supplemental oxygen). In the 6M with MIVV the tidal volume was identical to the previously titrated for each patient. Initial and final values of oxygen saturation (SpO2), Heart Rate, Borg scale, distance walked (meters) and maximum time performed (minutes) were measured in each 6M. Due to severe respiratory impairment (FVC - 18% predicted), there was one patient that could not perform the walking test without MIVV. Results : Exercise tolerance was improved in every patient during the six-minute walking test with MIVV. The distance walked increased 58%(151± 120 vs 238± 86, p<0,05) and initial SpO2 also increased (92 ± 3 vs 97 ± 3, p<0,05). Despite no statistically significant differences, we found improvement with MIVV in the duration of the walking test (4 ± 2,5 vs 5,4 ± 1,4 min), and medium oxygen desaturation (11,7 vs 8,7%). Conclusions : This study shows that intermittent volume ventilation by mouthpiece increases the distance walked, preventing and delaying desaturation, thus improving exercise tolerance in severe restrictive patients.
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