Buspirone as a Potential Treatment for Recurrent Central Apnea (CSA treatment)

• Apnea-hypopnea index (number of central and mixed apneas/hour of sleep) [ Time Frame: single night polysomnogram ] [ Designated as safety issue: No ]
  

The hypothesis is that buspirone is a safe, effective drug to reduce the occurrence of recurrent central apnea and irregular breathing found in the setting of heart failure. A secondary hypothesis is that its effect will be similar to that or acetazolamide. Study Design: A one-dose double-blind crossover study of buspirone vs. placebo vs. acetazolamide will be performed to determine if active drug alters the number and/or severity of recurrent central apneas and hypopneas (AHI) in patients with heart failure. AHI is the primary outcome variable. In the initial phase of this study, we will recruit 18-20 patients to obtain ~15 complete studies, using the assumption of a ~20% drop-out, to reach a pre-set significance level of a 30% reduction in AHI in the drug groups with a power of 0.90 and a p=0.05 by post-hoc testing. Power estimates were calculated using the means and SDs derived from the population reported the study of acetazolamide by Javaheri et al (2006). A 30% reduction in AHI would be meaningful. A 15% dropout rate was present in the study by Javaheri et al (2006), but as our study is a three-way comparison, we chose a slightly higher rate. The reasons stated in these articles for a drop out included: viral illness, GI upset (on placebo or on theophyllin), tired of the sleep studies, and desire to terminate without cause. Statistical Analyses. Analysis of variance for repeated measures using Sidak's correction will be used to compare placebo, buspirone, and acetazolamide studies. For variables that are not normally distributed, Dunn's nonparametric test for multiple comparisons will be used. p > 0.05 will be considered significant. Mean values and SDs will be reported. This single dose, one night study is called Buspirone as a Potential Treatment for Recurrent Sleep Apnea I.

A one-week trial (Buspirone as a Potential Treatment for Recurrent Central Apnea II) is now (4/2010) in recruitment and will have similar end-points. Again the comparisons of buspirone, acetazolamide, and placebo. There are however measures of ventilatory control during the one week trial, to probe for potential mechanisms. The randomization will be in a block design, and the analysis will take into account the blocked design. We will recruit 30 patients to obtain ~27 complete studies, using the assumption of a ~25% drop-out, to reach a pre-set significance level of a 50% reduction in AHI in the drug groups with a power of 0.90 and a p=0.05 by post-hoc testing (see Table C below). Power estimates were calculated using the means and SDs derived from the population reported the study of a one week trial of acetazolamide by Javaheri, values similar to those in the drug trial for theophyllin. Our reasoning is that a 50% reduction in AHI would be most meaningful. Our drop-out rate in the one-night study is ~25%. Two were due to transportation related issues and one was dropped from the study for hypoglycemia, non-study related, due to diabetic control. There were no problems with GI distress, dizziness, or desire to terminate the study in the one-night trial, but these are possible problems in a one week trial.