Lidocaine Infusion Improves the Functionality of Intraoperative Nerve Monitoring During Thyroid Surgery: A Prospective, Randomized, Double-Blinded Study.

BACKGROUND: Intraoperative nerve monitoring (IONM) to assess the recurrent laryngeal nerve function during thyroid surgery is becoming the standard of care across many institutions. The successful deployment and data analysis from the IONM require complete laryngeal relaxation and reflex suppression. We investigated the role of intravenous lidocaine infusion (IVLI) to provide such operating conditions, under a lighter plane of anesthesia and fewer hemodynamic fluctuations. METHODS: Sixty-five patients were randomly assigned to lidocaine group (LG) or placebo group (PG) based on the computer-generated coding developed by the pharmacy department. The study medication (SM) was delivered by the pharmacist in a pre-filled coded syringe to the investigator 30 min prior to the surgery. All the patients were anesthetized by narcotic and inhalation based general anesthesia. The SM was administered at the rate of 1.5mg/kg/h following a loading dose of 1 mg/kg. Dragonfly® laryngeal surface electrode and Nerveana® nerve locator system were used for IONM during surgery. RESULTS: The proportion of patients requiring lower strength stimulating current (StMC) at 0.5 mA was significantly higher in the LG than in the PG (X2 (1, N = 61) = 10.1615, P = 0.001434). Similarly, the proportion of patients with the drop in the aggregate impedance level (DAIL) by < 50% at the end of surgery was significantly higher in the LG than in the PG (X2 (1, N = 61) = 15.982, P = 0.000064). In addition, the proportion of patients with the hypotensive episodes requiring rescue medications more than twice during surgery was significantly lower in the LG than in the PG (X2 (1, N = 61) = 0.0183, P < 0.05). CONCLUSIONS: The enhanced laryngeal relaxation and the reflex suppression afforded by the IVLI could have enabled a lower StMC to elicit a positive signal. The lower StMC promotes less intense laryngeal alterations as evidenced by the lower DAIL in the LG. IVLI can enhance the functionality of the IONM during prolonged operating time and the resultant increased number of IONM stimulations, while providing a stable hemodynamic environment.

Improving the functionality of intra-operative nerve monitoring during thyroid surgery: is lidocaine an option?

Intra-operative nerve monitoring (IONM) is rapidly becoming a standard of care in many institutions across the country. In the absence of neuromuscular blocking agents to facilitate the IONM, the depth of anesthesia required to abolish the laryngo tracheal reflexes often results in profound hemodynamic instability during surgery, necessitating the use of large doses of sympathomimetic amines. The excessive alpha and beta adrenergic effects exhibited by these agents are undesirable in the presence of cardiovascular co-morbidities. Trying to strike a balance frequently results in an unsatisfactory intra-operative course. In the course of the near total thyroidectomy performed on a 60-year-old female, we employed lidocaine infusion at 1.5 mg/kg/hour following a bolus dose of 1 mg/kg. The troublesome laryngo tracheal reflexes were successfully blunted and we were able to moderate the depth of anesthesia resulting in stable hemodynamics. A bispectral index monitor was employed to guard against "recall" and a train of four monitor was used to ensure the absence of inadvertent neuromuscular blockade. During the surgery, there was loss of signal on the left recurrent laryngeal nerve (RLN). The signal strength was restored by rotating the endotracheal tube on its long axis to realign the electrode with the vocal cords under Glidescope(®) visualization.

Intraoperative wake-up test in neonatal neurosurgery.

Intraoperative wake-up test (WPT) still remains the gold standard to monitor anterior spinal cord function during spinal surgery. However, the test requires patient cooperation and hence difficult to perform in very young children or mentally challenged. In this report, we describe a WPT in a newborn during surgical repair of a large myelomeningocele. We relied on mivacurium for intubation and the relaxant effect was allowed to wear-off to permit the use of intraoperative nerve stimulator. We used desflurane and propofol infusion for rapid titration of the anesthetic depth and BIS monitor to 'gauge' the 'wakefulness' of the child during the WPT. We employed lidocaine infusion to improve tolerance to the tracheal tube and to bestow beneficial effect on intracranial pressure during surgery and the WPT. The results of the WPT were judged to be satisfactory after confirming flexion and extension of the lower extremities at the hip and knee level, correlating it with the BIS values, and comparing it with the preoperative status. Frequently associated prematurity, higher possibility of remaining intubated in the immediate postoperative period and any new onset neurologic deficit not becoming apparent until after extubation makes intraoperative neuromonitoring relevant in this age group. Our methodology of management has permitted us to perform a delicate test safely and will allow us to repeat the WPT if needed during neonatal neurosurgery.

Efficacy of ketorolac in lieu of narcotics in the operative management of laparoscopic surgery for morbid obesity.

BACKGROUND: Prompt recovery of protective airway reflexes, freedom from pain, ability to cooperate with respiratory physical therapy, early ambulation and discharge from the postanesthesia care unit (PACU), coupled with a stable intraoperative environment have been desired goals of anesthesia management of morbidly obese patients. We used ketorolac in lieu of narcotics toward this goal and present our subjective and objective data in this study. METHODS: A total of 50 morbidly obese patients undergoing laparoscopic gastric bypass surgery were randomly assigned to 2 groups of 25 each. Group I received intravenous ketorolac perioperatively, which was continued 24 hours postoperatively. Group II received remifentanyl intraoperatively as a part of balanced anesthesia. Intraoperative hemodynamic stability was assessed based on blood pressure, pulse rate, and bispectral index score values. Postoperative pain intensity using a visual analogue scale, as well as the presence of nausea, vomiting, hypotension, or respiratory depression, were also recorded. RESULTS: Postoperative side effects, including pain, nausea, and vomiting; requirements for analgesics and antiemetic medications in the PACU; and the time spent in the PACU varied significantly between the 2 groups. Continued administration of ketorolac during the first 24 hours postoperatively led to improved patient satisfaction and more enthusiastic participation in respiratory physical therapy. CONCLUSIONS: Perioperative use of intravenous ketorolac up to 24 hours after laparoscopic gastric bypass surgery for morbid obesity helps provide a more stable intraoperative environment, earlier discharge from the PACU, and better outcome in this subset of patients.

Epidural buprenorphine in management of pain in multiple rib fractures.

BACKGROUND: Pain from multiple rib fractures may affect pulmonary function, morbidity, and length of stay in the intensive care units. This study describes some clinical characteristics of epidural buprenorphine, a lipophilic and partial opiate agonist with a higher micro receptor affinity than morphine, in combating the pain in multiple rib fractures. METHODS: The study was conducted prospectively over a 15-month period. A total of 27 patients admitted to the hospital with multiple rib fractures were studied. Buprenorphine at a concentration of 0.3 mg in 5-10 ml normal saline was administered epidurally, twice daily the first 24 h, thereafter once daily. Ventilatory function tests (including vital capacity, tidal volume, respiratory rate, and minute volume) and assessment of pain intensity using a simple, categorical, verbal rating scale were obtained before and after institution of analgesia. Any nausea, vomiting, hypotension, urinary retention, respiratory depression or pruritus were recorded. RESULTS: We found a significant improvement in ventilatory function tests during the 1st, 2nd, and 3rd day after epidural analgesia when compared with the preanalgesia levels (P < 0.001). Changes in the verbal rating scale demonstrated that epidural buprenorphine was associated with marked improvement in pain at rest and pain during coughing and deep breathing. None of our patients developed hypotension (<10% of the baseline), urinary retention or respiratory depression. Nausea, vomiting, and mild pruritus were the only reported complications. CONCLUSIONS: Epidurally introduced narcotic, like buprenorphine in saline, has been found to be effective in our study to achieve adequate analgesia in treatment of patients with multiple rib fractures. In addition, this methodology of pain relief eliminates the costly delivery system and early discharge, and allows walking epidurals and follow-up on outpatient basis.