Is Sedation of Choice in Thyroplasty Surgery? A Study on the Effects of Sedatives on Voice Quality

Abstract

In order to establish the ideal anesthetic protocol in thyroplasty type I surgery, where the intraoperative voice test is used to guide the medialization of the paralyzed fold, we have studied the effects of a sedation with midazolam premedication and adjusted intravenous doses of propofol and remifentanil on voice quality in patients without vocal fold pathology undergoing otorhinolaryngology surgery other than thyroplasty. Prospective cross-sectional study included 40 adult patients. A voice recording was performed when the patient was fully awake and when an appropriate level of conscious sedation was reached. Following premedication with midazolam at anxiolytic doses, remifentanil and propofol were administrated by target controlled infusion pumps (TCI). These results were compared with those obtained in a previous study carried out by the same team using intravenous bolus (IV) according to weight. The recorded voice analysis was performed using the computer program Praat (v.5.3.39) for a sustained vowel. All the parameters obtained from the acoustic analysis of the voice were altered after sedation with target controlled infusion in a statistically significant way. Comparing with bolus intravenous, harmonic and noise ratio (HNR) was the only parameter that decreased less in the TCI group. The state of sedation obtained using midazolam premedication, propofol and remifentanil adjusted intravenous doses alters significantly all the voice parameters, although this alteration is considerably less than the changes produced by the medication administered in bolus IV. According to these results, the sedation and the voice test during thyroplasty surgery would present a series of limitations when it comes to guiding the medialization of the paralyzed vocal fold and therefore it could not be considered as the ideal anesthetic protocol in thyroplasty surgery.