CENTRAL APNEA INDEX DECREASES AFTER PROLONGED TREATMENT WITH ACETAZOLAMIDE

Only a limited number of studies dealing with the epidemiology and the rapy of central sleep apnea syndrome (CA) are available. The treatment strategies are poorly defined and not well evaluated. The aim of our present study was to treat selected CA patients with low dose acetazol amide (ACET) for a longer time period than has been done before. Previ ous studies were performed with high dose ACET provoking severe metabo lic acidosis, not for more than 1 wk or only in obstructive apnea pati ents. Referred patients with suspicion of sleep-related breathing diso rders (SRBD) were included in the study if, after a first selection ni ght, their central apnea index (CAI) was > 5 or their apnea-hypopnea i ndex (AHI) > 10 and their obstructive apnea index (OAI) < 5. Of 327 sc reened patients, 14(4.3%) fulfilled these criteria. Patients were then treated with ACET (250 mg, 1 h before sleep). Polysomnography was rep eated once after one single dose (N2) and twice after 1-mo chronic tre atment without (N3) and with (N4) additional ACET administration. Afte r each study night, arterial blood gases and chemical drive were measu red. CAI (25.5 +/- 6.8 at N1) already decreased during N2(13.8 +/- 5.2 ) and further during N3(6.6 +/- 2.9) and N4(6.8 +/- 2.8)(p < 0.01). OA I remained unchanged. Total sleep time (TST) and sleep efficiency inde x (SEI) did not change significantly. The number of arousals decreased from 62 +/- 11 at N1 to 40 +/- 5 at N3(p = 0.019). All patients subje ctively improved with fewer complaints of hypersomnolence, falling asl eep during the day, memory losses, and tiredness in the morning (p < 0 .01). Pa-O2 improved from 77.0 +/- 2.7 (N1) to 91.0 +/- 2.4 mm Hg (N3) (p < 0.01), whereas pH dropped from 7.41 +/- 0.01 (N1) to 7.38 +/- 0. 01 (N4) (p < 0.01). It is concluded that chronic therapy with low dose ACET in patients with nonhypercapnic central sleep apnea improved the breathing pattern and pulmonary gas exchange and reduced daytime slee piness.