Background: Spinal anesthesia with sedation is a common anesthetic technique in infraumbilical surgeries. Dexmedetomidine has been widely used as a sedative during spinal anesthesia, and is recognized as an adjuvant that prolongs the duration of spinal anesthesia. We compared the effects of a continuous intravenous infusion of dexmedetomidine to provide intraoperative sedation on the duration of sensory and motor blockade induced by spinal anesthesia, with those of midazolam. Methods: A double-blind randomized controlled trial was performed on 40 patients, aged between 20 and 75 years, who requested intraoperative sedation, and were classified as American Society of Anesthesiologists (ASA) physical status I-II, and underwent elective surgeries under spinal anesthesia. After spinal anesthesia with 13 mg (2.6 ml) of 0.5% hyperbaric bupivacaine, patients were randomized to receive intravenous dexmedetomidine 3 μg/kg/h for 10 mins followed by an infusion of 0.5 μg/kg/h (Group D), or intravenous midazolam 0.15 mg/kg/h for 10 mins followed by an infusion of 0.025 mg/kg/h (Group M). Sedation was titrated to Observer's Assessment of Alertness/Sedation (OAA/S) score of 3. Sensory and motor blockade was evaluated using the pinprick test and modified Bromage scale, respectively. Results: The time taken to achieve OAA/S score 3 was similar in the two groups. The maximal level of sensory blockade was 5.3 ± 1.3 min in group D and 4.1 ± 1.5 in group M (P = 0.03). No significant differences were observed in the time taken to achieve the maximal level or the two-segment regression time of sensory blockade between the two groups. The time to sensory regression to the L2 level was significantly longer in group D than in group M (234.6 ± 78.1 mins versus 172.4 ± 41.

The authors encountered a case involving difficult intubation during anesthesia for revision of cervical fixation angle in a 62-year-old woman, with a history of chronic rheumatoid arthritis, who experienced dysphagia after initial posterior occipitocervical fusion to correct atlantoaxial subluxation. Two days after initial surgery, she developed trismus with neck flexion and dysphagia, and underwent revision surgery. General anesthesia was planned; however, tracheal intubation using the McGrath laryngoscope and bronchofiberscope was difficult, which prolonged anesthesia induction. Narrowing of the oral and pharyngeal cavities associated with overcorrection of the cervical spine was believed to be the reason for difficulty in manipulating the tracheal intubation devices. In posterior occipitocervical fusion, intraoperative evaluation of the occipito-second cervical vertebra (O-C2) angle is reported to be useful in preventing postoperative dyspnea and/or dysphagia, and avoids the need for revision of fixation angle. However, when revision surgery is needed, selection of airway management methods and tracheal intubation devices are important considerations because patients are likely to have restricted mobility in the cervical spine and narrowing of the oral and pharyngeal cavities.