Dysfunction of phrenic pacemakers induced by metallic rescue blankets

Phrenic pacing can restore diaphragmatic contractions in patients with cent ral respiratory paralysis. It relies on radiofrequency transmission of ener gy from an external unit to implanted receivers through circular coil anten nas. The case of a patient is reported in rt hom severe hypoventilation occ urred following the use of a metallic rescue blanket. The phenomenon was co nfirmed in two subsequent patients and during benchmark tests. Possible mec hanisms include reflection and diffusion of high frequency waves by a Farad ay-like effect. Patients with implanted devices relying on telemetric contr ol or powering, and their care givers, should be warned against the use of metallic rescue sheets.