# An Interesting Outcome of Central Sleep Apnea With Phrenic Nerve Stimulation Therapy

## TL;DR

A phrenic nerve stimulator improved severe central sleep apnea and cognitive function in a 60-year-old man.

## Contribution

Demonstrates successful treatment of severe CSA with phrenic nerve stimulation and cognitive improvements.

## Key findings

- Phrenic nerve stimulation reduced AHI from 63.4 to 11.4 per hour.
- CSA index resolved completely to 0.0 per hour post-implantation.
- Patient showed improved verbal fluency, math skills, and cognition.

## Abstract

Central sleep apnea (CSA) is secondary to inadequate ventilation during sleep, causing individuals to experience repeated hypoxic episodes with long-term consequences of oxygen desaturation, such as arrhythmias, hypertension, congestive heart failure, stroke, coronary artery disease, cognitive issues, increased risk of accidents, type 2 diabetes, and worsening Parkinson’s disease. The phrenic nerve stimulator, remedē System (ZOLL Respicardia, Inc., Minnetonka, MN) is indicated as treatment for moderate-to-severe CSA in adults. It works by stimulating the phrenic nerve, which, in turn, causes the diaphragm to contract and helps restore normal breathing patterns during sleep. A 60-year-old male with obesity, essential hypertension, seizure, and stroke with biventricular hemorrhage secondary to cerebral aneurysm was seen in a sleep medicine clinic for sleep apnea. His polysomnogram showed severe primary CSA with an apnea-hypopnea index (AHI) of 63.4 per hour, central apnea index of 51.8 per hour, and lowest oxygen saturation of 73% with nocturnal hypoxemia of 6.9 minutes below 88% oxygen saturation. After remedē System implantation, the patient’s WatchPAT® sleep study showed a residual AHI of 11.4 per hour, CSA index of 0.0 per hour, and lowest oxygen saturation 84% with nocturnal hypoxemia of 3.2 minutes below 88% oxygen saturation. In our unique case, we found significant improvement of AHI and resolution of CSA along with improvement in verbal fluency, mathematical skills, and cognition with the use of remedē System.