In an adult with persistent central sleep apnea despite a trial of fixed‑pressure continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) and a left‑ventricular ejection fraction (LVEF) ≥45%, what are the indications, contraindications, and initial settings for Adaptive Servo‑Ventilation (ASV) therapy?

ASV Therapy in Central Sleep Apnea with LVEF ≥45%

In adults with persistent central sleep apnea despite CPAP/BiPAP trials and LVEF ≥45%, ASV therapy is appropriate and safe, but should only be initiated after confirming ejection fraction >45% and documenting failure of simpler PAP modalities. 1, 2

Critical Safety Requirement

• Ejection fraction must be documented as >45% before considering ASV – this is the single most important safety determinant, as ASV is absolutely contraindicated in patients with LVEF ≤45% due to demonstrated increased all-cause and cardiovascular mortality in the SERVE-HF trial. 1, 2

Indications for ASV Therapy

ASV is indicated when the following criteria are met:

• Persistent central sleep apnea (AHI >15/hr with predominantly central events) despite optimal medical therapy for any underlying conditions. 3
• Documented failure of CPAP therapy – approximately 55% of patients will have persistent CSA (AHI ≥15/hr) after CPAP trial. 3
• Documented failure of BiPAP with backup rate – this represents the appropriate intermediate step before advancing to ASV. 1, 4
• LVEF confirmed >45% by echocardiography or other cardiac imaging. 1, 2

The American Academy of Sleep Medicine recommends a stepwise treatment algorithm: start with standard CPAP, progress to BiPAP with backup rate if CPAP fails, and consider ASV only if BiPAP proves inadequate. 1, 4

Absolute Contraindications

• Heart failure with LVEF ≤45% and moderate-to-severe central sleep apnea – this combination showed increased all-cause mortality (hazard ratio for cardiovascular death) and sudden cardiac death in the SERVE-HF trial despite reducing AHI. 3, 2

Initial ASV Settings

Based on the devices used in clinical trials and standard practice:

Expiratory Positive Airway Pressure (EPAP)

• Start with EPAP 4-5 cmH₂O to maintain upper airway patency and control any residual obstructive events. 3
• EPAP can be adjusted upward if obstructive apneas or hypopneas persist. 5

Inspiratory Pressure Support (IPS)

• Minimum pressure support: 0-3 cmH₂O (varies by device manufacturer). 3
• Maximum pressure support: typically 8-10 cmH₂O initially, which can be adjusted based on response. 3
• The device will automatically adjust IPS breath-by-breath between these limits. 1, 5

Target Ventilation

• Set to 90% of the patient's recent minute ventilation (this is typically automated by the device using a 3-minute moving average). 1
• This prevents both under-ventilation and over-ventilation while stabilizing breathing patterns. 1

Backup Rate

• Auto-backup respiratory rate is standard on ASV devices and adjusts dynamically. 1, 5
• The backup rate activates anticyclic to the patient's respiratory pattern to suppress central apneas. 5

Expected Pressure Range

• Total positive airway pressure during sleep typically ranges from 8-16 cmH₂O when combining EPAP and dynamic pressure support. 3

Clinical Efficacy Expectations

• ASV dramatically reduces AHI – studies show reduction from baseline AHI of 44-52/hr to 0.8-5/hr with ASV, significantly better than CPAP (AHI 31-34/hr) or BiPAP without backup rate (AHI 75/hr). 6, 7
• REM sleep improves from 10-12% at baseline to 18% with ASV. 6
• Response rate is approximately 64% achieving AHI <10/hr, with most patients reporting subjective improvement in sleep quality. 6

Monitoring Requirements

• Close monitoring and follow-up is mandatory when using ASV in any patient with heart failure, even with preserved ejection fraction. 1, 2
• Download device data regularly to assess adherence (note that SERVE-HF showed poor adherence at only 3.7 hours/night, which may have contributed to poor outcomes). 3
• Repeat sleep study at 1-3 months to document efficacy, as persistent CSA despite ASV may indicate need for alternative approaches. 3

Common Pitfalls to Avoid

• Never skip the stepwise approach – jumping directly to ASV without trying CPAP and BiPAP first is inappropriate, as simpler therapies may be effective and are less complex. 1, 4
• Never use ASV without confirming ejection fraction – this is a potentially fatal error given the mortality signal in reduced EF patients. 1, 2, 4
• Do not confuse device settings between manufacturers – SERVE-HF used EPAP 5 cmH₂O with minimum pressure support 3 cmH₂O, while ADVENT-HF used EPAP 4 cmH₂O with zero minimum pressure support, showing that settings vary. 3
• Avoid using oxygen as primary therapy – oxygen is only appropriate when PAP therapies fail or are contraindicated, not as first-line treatment. 4