Clinical applications of adaptive servoventilation devices: part 2

Adaptive servoventilation (ASV) is an automated treatment modality used to treat many types of sleep-disordered breathing. Although default settings are available, clinician-specified settings determined in the sleep laboratory are preferred. Depending on the device, setting choices may include a fixed expiratory positive airway pressure (EPAP) level or a range for autotitrating EPAP; minimum and maximum inspiratory positive airway pressure or pressure support values; and type of backup rate algorithm or a selectable fixed backup rate. ASV was initially proposed for treatment of central sleep apnea and Hunter-Cheyne-Stokes breathing associated with congestive heart failure (CHF), and numerous observational studies have demonstrated value in this setting. Other studies have reported varying efficacy in patients with complex sleep apnea syndromes, including those with mixtures of obstructive and central sleep-disordered breathing associated with CHF, renal failure, or OSA with central apneas developing on conventional positive airway pressure therapy. Patients with opioid-induced sleep apnea, both obstructive and central, may also respond to ASV. The variability in response to ASV in a given patient along with the myriad choices of specific models and settings demand a high degree of expertise from the clinician. Finally, randomized controlled studies are needed to determine long-term clinical efficacy of these devices.