PURPOSE: CSA occasionally develops during therapeutic CPAP titration studies in patient with obstructive sleep apnea (OSA). We hypothesized that these events will progressively improve with CPAP therapy.
METHODS: Prospective analysis of patients with OSA (Apnea-Hypopnea index ≥ 5 events/hour) who manifest CSA events defined by CSA index (CSAI) ≥ 5 events/hour during CPAP titration portion of split night study. Subjects with CSA on diagnostic polysomnogram (PSG), CHF, COPD, or cerebrovascular disease were excluded. All patients underwent transthoracic echocardiogram (TTE), pulmonary function tests (PFTs) and arterial blood gas (ABG). A repeat PSG on CPAP pressure determined during the baseline CPAP titration study after 8 weeks on average of adequate therapy was obtained. A p < 0.05 was considered statistically significant.
RESULTS: Ten patients were included in the study. The average daily CPAP use was 5.9±0.4 hours. The mean CSAI decreased from 21.2±16.6 to 2.5±5.2 events/hour (p=0.007). Complete resolution of CSA was observed in majority of patients (n=7). Significant CSA continued to occur only in one subject in whom diastolic heart failure was evident on TTE. Sleep efficiency (84.3±4.9 vs. 74.4±11.1, p=0.03), WASO (12.5±5.3 vs. 20.2±11.5, p=0.06) and total arousals (18.8±7.7 vs. 32.3±8.6, p<0.01) showed improvement compared to baseline study. The sleep architecture was characterized by a significant reduction in sleep stage 1 percentage on follow up study (5.1±1.2 vs. 7.8±2.8, p=0.01).
CONCLUSION: CPAP related central sleep apnea may be caused by the sleep fragmentation during initial CPAP titration as demonstrated by improvement in arousals, stage 1 and WASO with continued CPAP therapy.
CLINICAL IMPLICATIONS: CPAP initiated for the first time may be cumbersome resulting in frequent awakenings, arousals and sleep stages shifts, thus facilitating ventilatory instability and potentially leading to the generation of central sleep apnea. These events are self limited and will resolve with time in most patients.
DISCLOSURE: Tarek Dernaika, None.