SLEEP-DISORDERED BREATHING

Effects of CPAP on oxidative stress and nitrate efficiency in sleep apnoea: a randomised trial

A Alonso-Fernández^1,2, F García-Río³, M A Arias⁴, Á Hernanz⁵, M de la Peña^1,2, J Piérola^2,6, A Barceló^2,7, E López-Collazo⁸, A Agustí^1,2,9

¹ Department of Pneumology, Hospital Universitario Son Dureta, Palma de Mallorca, Spain
² CIBER Enfermedades Respiratorias, Palma de Mallorca, Spain
³ Department of Pneumology, Hospital Universitario La Paz, Madrid, Spain
⁴ Department of Cardiology, Hospital Virgen de la Salud, Toledo, Spain
⁵ Department of Biochemistry and Molecular Biology, Hospital Universitario La Paz, Madrid, Spain
⁶ Investigation Unit, Hospital Universitario Son Dureta, Palma de Mallorca, Spain
⁷ Department of Clinical Analysis, Hospital Universitario Son Dureta, Palma de Mallorca, Spain
⁸ Research Unit, Laboratory of Tumor Immunology, Hospital Universitario La Paz, Madrid, Spain
⁹ Fundación Caubet-CIMERA Islas Baleares. International Centre for Advanced Respiratory Medicine, Bunyola, Mallorca, Spain

Dr A Alonso-Fernández, Servicio de Neumología, Hospital Universitario Son Dureta, C/Andrea Doria 55, 07014 Palma de Mallorca, Spain; alberto.alonso{at}ssib.es

Background: Previous studies have presented contradictory data concerning obstructive sleep apnoea syndrome (OSAS), lipid oxidation and nitric oxide (NO) bioavailability. This study was undertaken to (1) compare the concentration of 8-isoprostane and total nitrate and nitrite (NOx) in plasma of middle-aged men with OSAS and no other known co-morbidity and healthy controls of the same age, gender and body mass index; and (2) test the hypothesis that nasal continuous positive airway pressure (CPAP) therapy attenuates oxidative stress and nitrate deficiency.

Methods: A prospective, randomised, placebo controlled, double-blind, crossover study was performed in 31 consecutive middle-aged men with newly diagnosed OSAS and 15 healthy control subjects. Patients with OSAS were randomised to receive sham CPAP or effective CPAP for 12 weeks. Blood pressure, urinary catecholamine levels and plasma 8-isoprostane and NOx concentrations were obtained before and after both treatment modalities.

Results: Patients with OSAS had significantly higher 8-isoprostane levels (median (IQR) 42.5 (29.2–78.2) vs 20.0 (12.5–52.5) pg/ml, p = 0.041, Mann-Whitney test) and lower NOx levels (264 (165–650) vs 590 (251–1465) µmol/l, p = 0.022) than healthy subjects. Body mass index, blood pressure and urinary catecholamines were unchanged by CPAP therapy, but 8-isoprostane concentrations decreased (38.5 (24.2–58.7) pg/ml at baseline vs 22.5 (16.2–35.3) pg/ml on CPAP, p = 0.0001) and NOx levels increased (280 (177–707) vs 1373 (981–1517) µmol/l, p = 0.0001) after CPAP.

Conclusions: OSAS is associated with an increase in oxidative stress and a decrease in NOx that is normalised by CPAP therapy.

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