Researchers showed the case of a 65-year-old man undergoing a two-level lumbosacral posterior spinal fusion under general anesthesia using dexmedetomidine, lidocaine, and nitrous oxide, without the use of any intraoperative opioids and minimal opioids postoperatively for 24 h. To our knowledge, this is the first report documenting this anesthetic technique and its benefits through the first postoperative day.
A 65-year-old man with a history of hypertension, obesity, congenital bicuspid aortic valve status post-aortic valve replacement, pacemaker for postoperative bradycardia, and lumbar spinal stenosis presented for L4-S1 posterior lumbar fusion. His preoperative medications included aspirin 81 mg daily, metoprolol extended-release 50 mg daily, and lisinopril 5 mg daily. General anesthesia was induced using dexmedetomidine (1 µg/kg over 10 min, started 10 min pre-induction), lidocaine (1.5 mg/kg), propofol (2 mg/kg), and succinylcholine (1 mg/kg).
Following tracheal intubation, general anesthesia was maintained with intravenous infusions of dexmedetomidine (1 µg/kg/h), lidocaine (1.5 mg/kg/h), and inhaled nitrous oxide: oxygen (70: 30). Intraoperatively, the patient required a phenylephrine infusion for the majority of the procedure (range, 10–25 µg/min); this was discontinued 5 min before extubation. The patient's intraoperative heart rate did not vary significantly from his baseline heart rate. He was not pacemaker-dependent and the lower heart rate limit for active pacing was set at 50 beats/min.
The dexmedetomidine infusion was discontinued approximately 30 min before the completion of surgery. The lidocaine infusion was discontinued immediately after extubation. The patient was extubated after a total operating time of 7.5 h without any complications. The patient did not receive any opioids intraoperatively. Within 3 min of extubation, the patient was awake and alert with an intact neurological exam. The patient denied experiencing pain in the operating room and on arrival at the post-anesthesia care unit (PACU). The patient used a total of 0.4 mg of hydromorphone during his 90-min PACU stay via patient-controlled analgesia.
Lidocaine has been used as an intravenous adjunct to control intraoperative pain and decrease postoperative pain scores. Lidocaine's analgesic effect can extend for months following surgery, possibly due to sustained concentrations of lidocaine in the cerebrospinal fluid. The exact mechanism of lidocaine's benefits remains unclear. Traditionally, the mechanism of local anesthetics has been attributed to their membrane-stabilizing effect via the inhibition of voltage-gated sodium channels. More recent studies suggest a reduction in central sensitivity and hyperalgesic pathways, inhibition of N-methyl-D-aspartate (NMDA) receptors, and a decrease in inflammatory biomarkers as contributing mechanisms.
Avoiding opioids can also prevent associated adverse effects, including nausea, constipation, pruritus, sedation, hormonal and immunologic dysfunction, respiratory depression, and death. Given the high incidence of chronic pain and increased opioid use after spinal fusion surgery, perioperative analgesic methods that reduce pain and the need for opioids may be especially beneficial for patients undergoing this procedure. This technique also avoids the risk of hyperalgesia associated with the intraoperative use of opioids, especially remifentanil.