Central sleep apnea (CSA) is a disorder with a variable clinical presentation. Abnormalities in gain of metabolic ventilatory control system or circulatory abnormalities may contribute to unstable, periodic ventilation during sleep. Acetazolamoide (ACET) is known to potentiate the ventilatory response to chemical stimuli and to alter brain blood flow. Likely, via one or both these mechanisms, ACET has been found to improve sleep-induced periodic breathing and central sleep apnea. Worsening of obstructive sleep apnea (OSA) has also been reported with ACET. Based on these concepts, we hypothesized that in patients, primarily with CSA but with mild OSA, CSA would be improved and OSA worsened by ACET.
Patients were selected with a Central AH index > 5/h and OSA index < 5/hr. Central Apnea/Hypopnea and obstructive Apnea/Hypopnea were defined using standarized polysomnographic (PSG)criteria. In an open label, prospective study of 8 patients diagnosed with CSA, ACET 250 mg orally bid was administered for 6 weeks, followed by repeat PSG in the last week of therapy.
Average age was sixty-one, race distribution C/AA 4/4 and gender difference M/F 7/1. Respiratory disturbance index (RDI) decreased by approximately 50%, but because of variability and small group size, this was not statistically significant (42 ± 12 vs. 20 ± 14 P = NS). Central apnea index (16 ± 16 vs. 2 ± 3 P = .0001) and central hypopnea index (20 ± 15 vs. 3 ± 4 P =.019) improved during NREM and REM sleep. Obstructive AH index (1 ± 2 vs. 15 ± 10 P = .001) worsened with ACET. ACET use did not improve Epworth sleepiness scale (ESS) (12 ± 5 vs. 9 ± 5 P = NS) .
Acetazolamide tended to decrease the overall RDI, but primarily changed the sleep disordered breathing pattern in CSA patients.
We speculate that ACET may influence respiratory pattern generation but worsen factors contributing to upper airway collapse during sleep.
I. Sharief, None.