title: Influence of intravenous anesthetics on neuromonitoring of the recurrent laryngeal nerve during thyroid surgery.
abstract: Limited reports are available in the literature on the impact of intravenous administration of anesthetics on laryngeal electromyographic (EMG) activity. The purpose of this study was to determine the influence of the two commonly used intravenous anesthetics (propofol and thiamylal) on EMG amplitude evoked from the recurrent laryngeal nerve (RLN) during thyroid surgery. A total of 40 patients were randomized to receive a bolus of propofol (0.5 mg/kg; n = 20) or thiamylal (1.5 mg/kg; n = 20) to increase anesthetic depth when the surgeon found patient movement intraoperatively. Evoked potentials were obtained before and every 1 minute after the administration of each agent for up to 5 minutes by stimulating the RLN. The magnitude of evoked potentials at each time point and hemodynamic response were compared within groups. The mean amplitude of evoked potentials did not change significantly after administration of either propofol or thiamylal (p > 0.05 within groups). Mean arterial pressure measured from 1 minute to 5 minutes was significantly lower in the propofol group than in the thiamylal group (p < 0.05). Heart rate measured within 5 minutes did not differ significantly within groups. Low dose of propofol (0.5 mg/kg) or thiamylal (1.5 mg/kg) did not affect EMG readings during neuromonitoring of the RLN in thyroid surgery. Our results show that thiamylal provides better hemodynamic stability than propofol, and is therefore a preferable agent to increase anesthesia depth and prevent further patient movement during intraoperative neuromonitoring.
authors.affiliation: Department of Anesthesiology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung, Taiwan.
authors.forename: Pi-Ying
authors.initials: PY
authors.lastname: Chang
authors.affiliation: Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Otorhinolaryngology-Head and Neck Surgery, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
authors.forename: Che-Wei
authors.initials: CW
authors.lastname: Wu
authors.affiliation: Department of Anesthesiology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; Department of Nursing, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
authors.forename: Hsiu-Ya
authors.initials: HY
authors.lastname: Chen
authors.affiliation: Department of Nursing, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
authors.forename: Hui-Chun
authors.initials: HC
authors.lastname: Chen
authors.affiliation: Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Anesthesiology, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
authors.forename: Kuang-I
authors.initials: KI
authors.lastname: Cheng
authors.affiliation: Department of Anesthesiology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung, Taiwan; Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Institute of Clinical Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan. Electronic address: u9251112@gmail.com.
authors.forename: I-Cheng
authors.initials: IC
authors.lastname: Lu
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; Department of Otorhinolaryngology-Head and Neck Surgery, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Feng-Yu
authors.initials: FY
authors.lastname: Chiang
mesh_terms: D018686:Anesthetics, Intravenous / Q000008:administration & dosage / Q000494:pharmacology*; D062186:Arterial Pressure / Q000187:drug effects; D004576:Electromyography; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D064926:Neurophysiological Monitoring; D015742:Propofol / Q000008:administration & dosage / Q000494:pharmacology; D012009:Recurrent Laryngeal Nerve / Q000187:drug effects*; D013840:Thiamylal / Q000008:administration & dosage / Q000494:pharmacology; D013961:Thyroid Gland / Q000187:drug effects / Q000601:surgery*
chemical_list: D018686:Anesthetics, Intravenous; D013840:Thiamylal; D015742:Propofol
keywords: Intraoperative neuromonitoring; Propofol; Recurrent laryngeal nerve; Thiamylal; Thyroid surgery