What is the role of volume assured pressure support (VAPS) in the treatment of central sleep apnea?

Volume Assured Pressure Support in Central Sleep Apnea Treatment

Volume assured pressure support (VAPS) is an effective treatment option for central sleep apnea (CSA), reducing apnea-hypopnea index (AHI) significantly in approximately 42% of patients, though it should be considered after first-line therapies have failed. 1

Mechanism and Effectiveness

• VAPS automatically adjusts inspiratory positive airway pressure (IPAP) between set minimum and maximum limits to deliver a targeted tidal volume, helping prevent the hypoventilation that characterizes central sleep apnea 2
• VAPS can be used in spontaneous, spontaneous-timed (ST), or timed modes, with ST mode recommended for patients with central apneas due to the importance of a backup rate 2
• In a retrospective study, VAPS reduced AHI from 63.3 ± 19.1 to 30.5 ± 30.3 events/hour (p<0.003) in patients with CSA, with 42% of patients achieving an AHI <15 events/hour 1

Clinical Application and Settings

• Initial recommended settings for VAPS include:

  • EPAP = 4 cm H₂O
  • IPAP min = EPAP + 4 cm H₂O
  • IPAP max = 25-30 cm H₂O
  • Target tidal volume = approximately 8 mL/kg ideal body weight 2

• A backup rate should always be used (ST mode) in patients with central hypoventilation, central apneas, or inappropriately low respiratory rates 2

• Starting backup rate should equal or be slightly less than the spontaneous sleeping respiratory rate (minimum 10 breaths/minute) 2

• IPAP time should be set to provide an inspiratory time between 30-40% of the cycle time 2

Advantages Over Standard Pressure Support

• Standard pressure support ventilation (PSV) can worsen sleep quality and induce central apneas in 54% of patients due to hyperventilation and hypocapnia 2, 3
• PSV-induced central apneas lead to arousals, awakenings, and sleep fragmentation 2
• VAPS addresses this issue by automatically adjusting pressure to maintain consistent ventilation and prevent hypocapnia 1
• The backup rate in ST mode prevents central apneas that might occur with fixed pressure support 2, 3

Patient Selection

• VAPS may be particularly beneficial for:

  • Patients with CSA who have failed CPAP therapy 4
  • Patients with treatment-emergent central sleep apnea 4
  • Patients with CSA related to opioid use 1, 5
  • Patients with CSA and Cheyne-Stokes respiration 1

• Caution is warranted in heart failure patients with reduced ejection fraction, as adaptive servoventilation (a similar but distinct technology) has been associated with increased mortality in this population 6

Titration Protocol

• VAPS titration with polysomnography is the recommended method to determine effective settings 2
• EPAP should be adjusted first to eliminate obstructive events 2
• Pressure support should be increased if:
  • Tidal volume is low (<6-8 mL/kg)
  • Arterial PCO₂ remains elevated
  • SpO₂ remains below 90% 2
• Backup rate should be increased in 1-2 breaths per minute increments every 10 minutes if goals are not met 2

Monitoring and Follow-up

• Sleep architecture, AHI, oxygen saturation, and PCO₂ levels should be monitored during titration 2
• Transcutaneous or end-tidal PCO₂ may be used to adjust settings if properly calibrated 2
• Patient comfort and mask fit are essential for adherence 2

Common Pitfalls and Limitations

• VAPS may not be effective for all patients with CSA, with approximately 58% not achieving optimal AHI reduction 1
• Higher BMI may be associated with reduced effectiveness of VAPS in some patients 4
• Lack of hypertension has been identified as a predictor of better response to VAPS therapy 1
• Patient-ventilator asynchrony can occur and should be minimized through careful titration 2