A retrospective case series of adaptive servoventilation for complex sleep apnea.

STUDY
OBJECTIVES: Central sleep apnea can be refractory to traditional positive airway pressure (PAP) therapy (CPAP or bilevel PAP), whether appearing first as a feature of baseline polysomnography or only later once PAP is applied in what is termed "complex sleep apnea" (CompSA). This retrospective study examined the efficacy of adaptive servoventilation (ASV) in 25 consecutive patients with PAP-refractory central sleep apnea, most exhibiting predominantly obstructive apnea during baseline polysomnography.
METHODS: Patient characteristics were: age = 59.8 ± 16.5 yr; BMI = 30.4 ± 6.1 kg/m(2); apnea/hypopnea index (AHI) = 48.5 ± 30.2/h; and central apnea index (CAI) = 10.8 ± 16.0/h. Following unsuccessful PAP titrations, patients underwent ASV titration. Eighteen met established criteria for CompSA.
RESULTS: On traditional PAP, AHI did not improve significantly compared to baseline, whether based on the entire titration (38.5 ± 23.4/h, p = 0.10) or the final PAP pressure(s) (44.4 ± 25.9/h, p = 0.54); CAI tripled across the titration (27.4 ± 23.5/h, p = 0.001) and at the final pressure(s) (34.8 ± 24.2/h, p < 0.001). On ASV, AHI fell to 11.4 ± 8.2/h across the titration (p < 0.001) and decreased further to 3.6 ± 4.2/h at the optimal end expiratory pressure (p < 0.001). AHI was ≤ 5/h in 80% of patients and < 10/h in 92%. ASV virtually eliminated central apneas at optimal end expiratory pressure (0.7 ± 2.2/h, p < 0.001). Respiratory arousals showed parallel improvements on ASV but not PAP.
CONCLUSIONS: ASV proved superior to traditional PAP in reducing the AHI, CAI, and respiratory arousals in a heterogeneous patient group with sleep disordered breathing in whom central apneas emerged or persisted on PAP.