Adaptive Servo Ventilation Therapy
Mechanism of Action and Technical Operation
- The American Academy of Sleep Medicine describes Adaptive Servo Ventilation (ASV) as a form of bilevel positive airway pressure (BPAP) therapy that provides dynamic, breath-by-breath adjustment of inspiratory pressure support and an auto-backup respiratory rate, primarily used to treat central sleep apnea (CSA) and complex sleep-disordered breathing 1
- ASV differs from standard CPAP or BPAP by providing expiratory positive airway pressure (EPAP) that can be adjusted to control obstructive events, similar to CPAP, and dynamic inspiratory pressure support (IPS) that adjusts breath-by-breath based on the patient's ventilatory pattern 1, 2
- The device uses a three-minute moving average to monitor and determine an appropriate target minute ventilation, typically set to 90% of the patient's most recent minute ventilation, to prevent both under-ventilation and over-ventilation 2
- ASV functions as a hybrid system that combines a baseline of CPAP and periodic ventilatory support provided during central apneas, with the cumulative positive airway pressure during sleep typically ranging from 8 to 16 cmH₂O 3, 4
Clinical Efficacy and Safety
- The American Academy of Sleep Medicine recommends a stepwise approach to treating complex sleep apnea, starting with standard CPAP as first-line therapy, progressing to BPAP with backup rate if CPAP fails, and considering ASV only if BPAP proves inadequate and ejection fraction is >45% 6
- ASV is absolutely contraindicated in patients with heart failure and ejection fraction ≤ 45% with moderate or severe CSA due to demonstrated increased all-cause and cardiovascular mortality, as shown in the SERVE-HF trial 5, 6
Appropriate Clinical Applications and Treatment Algorithm
- The American Academy of Sleep Medicine recommends obtaining ejection fraction before considering ASV, as this is the critical safety determinant, and considering ASV only if BPAP proves inadequate and ejection fraction is >45% 6
- ASV may be considered in patients with CSA in heart failure with ejection fraction > 45%, with close monitoring and follow-up 5, 6