title: Should flow-volume loop be monitored in sleep apnea patients treated with continuous positive airway pressure?
abstract: Nasal continuous positive airway pressure (nCPAP) has been widely established in the treatment of obstructive sleep apnea syndrome (OSAS). However, only few studies have evaluated long-term effects of this treatment on lung function. This study assesses the effect of nCPAP on lung function parameters and response to bronchodilators in 50 OSAS patients. Spirometry and arterial blood gas measurements were performed before starting nCPAP and after 16.8 +/- 8 months of treatment. Of the 50 study patients (55 +/- 12 years, with an apnea/hypopnea index of 47 +/- 34h(-1)), 15 had asthma, 13 had chronic obstructive pulmonary disease (COPD) and 22 had no obstructive airway disease (NOAD). In the entire population, significant decreases in FEF50 (from 69 +/- 38% to 61 +/- 30%, P < 0.005), FEF25 (from 53 +/- 34% to 46 +/- 28%, P < 0.05) and FEF25-75 (from 65 +/- 33% to 57 +/- 27%, P < 0.005) were observed after treatment. No impairment of lung function was found in COPD and asthmatic patients. In contrast, lung function was changed in the NOAD group where FEF50, FEF25 and FEF25-75 as well as FEV1 and FEV1/VC ratio were significantly reduced. Moreover, bronchial hyperresponsiveness occurred in five of 22 patients of this group. These results suggest that tolerance of nCPAP should be handled by long-term follow-up of flow-volume loops.
authors.affiliation: Service de Physiologie-Explorations Fonctionnelles, Hôpital Louis Mourier (AP-HP), 178, rue des Renouillers, Colombes 92700, France.
authors.forename: Marcel
authors.initials: M
authors.lastname: Bonay
authors.forename: Alain
authors.initials: A
authors.lastname: Nitenberg
authors.forename: Dominique
authors.initials: D
authors.lastname: Maillard
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001249:Asthma / Q000150:complications / Q000628:therapy; D016535:Bronchial Hyperreactivity; D001993:Bronchodilator Agents / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000503:physiopathology*; D008297:Male; D008449:Maximal Expiratory Flow-Volume Curves; D008875:Middle Aged; D010991:Plethysmography; D011175:Positive-Pressure Respiration / Q000009:adverse effects*; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000628:therapy; D012129:Respiratory Function Tests; D012891:Sleep Apnea Syndromes / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D013147:Spirometry
chemical_list: D001993:Bronchodilator Agents