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The US Food and Drug Administration (FDA) approved an implanted phrenic nerve-stimulator device as a new treatment for moderate-to-severe central sleep apnea (CSA).
The remedē System (Respicardia) consists of a pacemaker-like battery pack that’s surgically implanted in the upper chest beneath the skin. Wires electrically stimulate the phrenic nerve as it travels from the neck to the diaphragm. The system delivers phrenic nerve impulses while also monitoring the patient’s respiratory signals during sleep, to integrate stimulated breaths with natural breathing.
Respicardia treats central sleep apnea, in which the brain fails to send signals to breathe through the phrenic nerve. Central sleep apnea often coexists or is caused by other conditions like strokes and congestive heart failure. Untreated CSA can result in irregular breathing and low oxygen levels overnight. Because the usual treatments for obstructive sleep apnea (continuous positive airway pressure and its cousins) rely on natural breathing, they don’t fully correct central sleep apnea.
FDA approved remedē System after a small clinical trial in 141 patients, who were implanted with either the working system or an inactivated device. At six months of followup, about half the patients with the Respicardia system had a ≥50% decrease in their apnea-hypopnea index (number of impaired breathing events per hour). Only one in 9 patients with a deactivated system had a similar improvement in overnight breathing.
Generally speaking, the FDA has a much less rigorous review process to approve devices, compared to drugs. Manufacturers must prove the device is safe, probably effective, and roughly comparable to existing devices.
Patients with the implanted phrenic nerve stimulators occasionally experienced infections, interference with other devices like pacemakers, and erosion of the device into adjacent tissues. The device is not compatible with magnetic resonance imaging (MRI). Respicardia was not approved for patients with obstructive sleep apnea. Those OSA patients can get their own implantable tongue-buzzing nerve stimulator.