A Comparison of Anesthetic Techniques for Awake Intubation in Neurosurgical Patients:

Two different methods of achieving upper airway anesthesia for awake fiberoptic intubation were prospectively compared in patients undergoing surgery for cervical spine instability. Forth patients were randomized to either topical anesthesia or nerve block groups. Topical anesthesia patients were administered nebulized 4% lidocaine (approximately 20 ml) via the oropharynx plus a transtracheal injection of 4% lidocaine (3 ml). Nerve block patient underwent bilateral glossopharyngeal and superior laryngeal nerve blocks with 2% lidocaine (0.5-2 ml per injection site) plus a transtracheal injection of 4% lidocaine (3 ml). The quality of anesthesia for intubation was graded by observers blinded to group assignment. Mean arterial pressure, heart rate, Pao2, Paco2, pHa, SpO2, and plasma lidocaine concentrations were measured during the intubation sequence. Patient recall of intubation and discomfort were assessed during the postoperative period with visual analog scales. Time required for successful intubation and quality of intubation and discomfort were not different between groups. Physiologic values for the two groups were similar. The mean total dose of lidocaine in the topical anesthesia group was approximately 2 times greater than that in the nerve block group (815 versus 349 mg; p < 0.0001). In contrast, mean plasma lidocaine concentration at initiation of intubation in the topical anesthesia group was half that of nerve block group (2.16 versus 4.23 mug/ml; p < 0.0001). Ten minutes later there was no difference of seizures lidocaine concentration between groups. No patients had evidence of seizures or neurologic change during the procedure. Patients in the topical anesthesia group recalled change during the procedure. There was no difference in patient perception of discomfort during the procedure. Patients in the topical anesthesia group recalled the intubation better than those in the nerve block group (p = 0.004). Both techniques for airway anesthesia were found to be similarly safe and effective and offer alternatives when patients with cervical spine disorder require awake oral fiberoptic intubation of the trachea.