Mild Hypothermia During Cochlear Implantation

Hypothermia has been shown to have a protective effect following trauma to the central nervous system and the peripheral auditory system. We have previously demonstrated a protective effect of mild hypothermia on auditory function caused by cochlear implant electrodes in animal models. Preservation of residual hearing of patients undergoing cochlear implantation is highly desirable and based on these animal studies, it may be possible to achieve in human subjects using mild degrees of hypothermia. We propose to investigate the hypothesized protective effect of intra-operative hypothermia on adult subjects undergoing cochlear implantation.

Inclusion Criteria: Adults greater than or equal to 18 years of age with some measurable auditory function who are undergoing cochlear implantation as routine management of severe to profound hearing loss.

Exclusion Criteria: Pure tone average hearing (mean of .5, 1 and 2 KHz) worse than 100dB; Age > 70 years; History of arrhythmia or ischemic heart disease; sickle cell trait or disease; immune incompetence; coagulation disorders; revision cochlear implant; body-mass index > 35; cold related disorders.

Phase I: Up to 40 healthy adult subjects who have qualified for CI will undergo implantation with core body temperature lowered to 34 degree Centigrade for approximately one hour before electrode insertion and 30 minutes after insertion. Otherwise, the surgical technique will be unchanged from our standard procedure.

The heating/cooling blanket is an FDA approved device. similar temperature controlling blankets are used in virtually all operations done under general anesthesia. Each subject's temperature will be gradually lowered only after they are put to sleep. Warming will being at least 30 minutes before the subject is awakened. We will measure and record the subject's temperature every 5 to 15 minutes while they are in the operating room and also while they are in the recovery room.