Is there a role for phrenic nerve stimulators (PNS) in treating treatment-emergent central sleep apnea (CSA)?

Role of Phrenic Nerve Stimulators in Treatment-Emergent Central Sleep Apnea

Phrenic nerve stimulation should not be considered a first-line treatment for treatment-emergent central sleep apnea (TECSA), but may be considered as a salvage therapy when other treatments have failed and the patient has moderate-to-severe persistent CSA despite optimal management of underlying conditions. 1

Understanding Treatment-Emergent Central Sleep Apnea

Treatment-emergent central sleep apnea (TECSA) is a form of central sleep apnea that develops during treatment of primary obstructive sleep apnea, most commonly with positive airway pressure therapy, but can also occur with other treatments including hypoglossal nerve stimulation 2.

Treatment Algorithm for TECSA

First-Line Approaches

1. Optimize underlying condition management

   • For patients with heart failure, optimize heart failure treatment according to cardiology guidelines 1
   • Address any traumatic brain or spinal cord injury if present 1
   • Improve sleep hygiene and treat any coexisting obstructive sleep apnea 1

2. Positive Airway Pressure Therapy Adjustments

   • Continuous positive airway pressure (CPAP) may help alleviate heart failure and can reduce AHI in approximately 45% of patients with CSA 3
   • Consider waiting 3 months on CPAP therapy as TECSA often resolves spontaneously

Second-Line Options

1. Supplemental Oxygen Therapy

   • May be considered for persistent CSA, though evidence is limited 1
   • Use with caution in heart failure patients as supplemental oxygen alone may impair cardiac function 3

2. Adaptive Servo-Ventilation (ASV)

   • Consider for persistent, severe cases of CSA without contraindications 1
   • IMPORTANT CONTRAINDICATION: ASV is contraindicated in heart failure patients with reduced ejection fraction (EF ≤45%) due to increased cardiovascular mortality 1

Salvage Therapy: Phrenic Nerve Stimulation

When considering phrenic nerve stimulation for TECSA, the following should be evaluated:

1. Patient Selection Criteria:

   • Moderate-to-severe CSA that persists despite optimal management of underlying conditions 1
   • Failure of other treatment options 1
   • No contraindications for implantable devices 1

2. Efficacy Considerations:

   • Transvenous phrenic nerve stimulation (TPNS) has shown a significant reduction in apnea-hypopnea index (AHI) and central apnea index (CAI) 4, 5
   • Studies have demonstrated improvements in quality of life and sleepiness 4
   • In heart failure patients, improvements in left ventricular ejection fraction and 6-minute walk distance have been reported 6

3. Safety Considerations:

   • Risk of serious adverse events in approximately 1 in 10 patients 3, 1
   • Common complications include lead dislodgement, particularly in the early post-implantation period 6, 4
   • The procedure is minimally invasive but requires specialized expertise 7

Implementation Challenges

1. Limited Access:

   • Patient access to TPNS therapy remains limited due to the small number of specialized centers 7
   • Reimbursement issues may further restrict availability 7

2. Program Requirements:

   • Successful implementation requires establishment of a specialized multidisciplinary program 7
   • Support from healthcare systems and hospitals is essential 7

Clinical Monitoring and Follow-up

For patients who receive phrenic nerve stimulation:

• Regular follow-up is essential, particularly in the first month post-implantation due to risk of lead dislodgement 6
• Monitor for improvements in sleep parameters, quality of life, and cardiac function in heart failure patients 4
• Adjust stimulation parameters as needed, noting that higher voltages may sometimes trigger central events 2

Conclusion

While phrenic nerve stimulation shows promise for treating persistent central sleep apnea, including treatment-emergent CSA, it should be reserved for cases where first-line and second-line therapies have failed. The decision to use this therapy must carefully weigh potential benefits against risks, considering the underlying etiology of CSA and patient-specific factors.