Phrenic Nerve Stimulation and Automatic Positive Airway Pressure Therapy for Treating Central Sleep Apnea and Residual Obstructive Sleep Apnea: A Case Study

Abstract

Introduction Central sleep apnea (CSA) is a neurological breathing disorder resulting from intermittent disruptions in the neural drive to breath. CSA and obstructive sleep apnea (OSA), caused by partial or complete blockage of the airway, frequently occur together. The remedē System (Respicardia, Minnetonka, MN) is an implantable device that delivers phrenic nerve stimulation therapy (PNS) to treat moderate to severe CSA. A remedē System pivotal trial patient presented following failure with mask-based therapies with baseline (BL) Apnea Hypopnea Index (AHI) 98.1 events/hour; Central Apnea Index (CAI)=60.8/Obstructive Apnea Index (OAI)=13.4/Mixed Apnea Index (MAI)=5.4/Hypopnea Index (HI)=18.4). The patient has a complex cardiovascular history including heart failure and classic sleep apnea symptoms. Hypothesis The combination of PNS and APAP for patients with CSA and residual OSA is feasible. Methods Patient was implanted with the PNS device and titrated to maximum effectiveness. Follow-up polysomnograms (PSG) were completed every 6 months. Results At the 6 month PSG, the patient transitioned from CSA into an OSA/OSA hypopnea pattern; Central Sleep Apnea Index (CAI)=1.4/Obstructive Apnea Index (OAI)=28.3/Mixed Apnea Index (MAI)=0.1/ Hypopnea Index (HI)=44.1 with Obstructive Hypopnea Index (OHI)=43.7 and this continued at the 12 month PSG. Mask-based therapy (APAP) was then added to supplement the PNS and the combination therapy was assessed during a routine PSG. Final APAP pressures of 6cmH2O-12cmH2O were well tolerated. The PSG demonstrated that with PNS off, APAP therapy treated the obstructive (apnea/hypopnea) events but did not treat the central events. PNS alone treated the CSA but did not resolve OSA (apnea/hypopnea) events. With both PNS and PAP therapy on, CSA and OSA were controlled and breathing was normalized (AHI 3.8). PSG testing at 18 months with PNS and APAP showed the AHI was reduced by 90% including a reduction in all AHI components; Central Apnea Index (CAI)=0.0/Obstructive Apnea Index (OAI)=3.9/Mixed Apnea Index (MAI)=0.0/Hypopnea Index (HI)=6.1). Epworth Sleepiness Scale improved (BL=14/6mo=4/9mo=5/12mo=6). PSG testing at 24 months with PNS on and APAP therapy off showed residual presence of hypopnic OSA and continued successful treatment of CSA; Central Apnea Index (CAI)=0.4/Obstructive Apnea Index (OAI)=0.8/Mixed Apnea Index (MAI)=0.0/Hypopnea Index (HI)=47.5 with Obstructive Hypopnea Index (OHI)=39.9). Patient remains treated with both PNS and APAP and sleeping well. Conclusion PNS effectively treated CSA. APAP therapy alone did not treat the CSA but did resolve obstructive apnea/hypopnea. Combination PNS and APAP safely and successfully treated both CSA and OSA.