Analgesic Efficacy of Intravenous Lidocaine for Postoperative Pain Following Adult Spine Surgery

The purpose of this study is to generate further insight into the role and effectiveness of the amide local anesthetic lidocaine as an adjuvant postoperative analgesic after adult spine surgery. The effect of perioperative intravenous lidocaine infusion on postoperative rehabilitation and the inflammatory response will also be examined.

Inadequate pain control after spine surgery in adults can result in increased patient morbidity and length of hospital stay, whereas improved postoperative pain control has been demonstrated to have numerous physiologic benefits and to reduce postoperative complications. When administered systemically, the amide local anesthetic lidocaine has potent anti-inflammatory properties, including inhibition of the arachidonic acid cascade and production of eicosanoids and prostaglandins. Previous studies have confirmed that the continuous intravenous administration of lidocaine during and after abdominal surgery in adults improves patient rehabilitation (specifically, pain intensity, duration of ileus, incidence of nausea and vomiting), and shortens hospital stay. The beneficial anti-inflammatory properties versus untoward side effects of the local anesthetics appear superior to steroids and the non-steroidal anti-inflammatory drugs (NSAIDs). Moreover, concern and controversy exists regarding the adverse effects of NSAIDs on bone healing, particularly in adults undergoing spine surgery.

No study to date has investigated the efficacy of a continuous perioperative lidocaine infusion in the adult spine surgery population. Therefore, in this prospective, randomized, controlled trial, we will evaluate the analgesic efficacy, anti-inflammatory properties, and rehabilitation pattern with a continuous, perioperative intravenous infusion of lidocaine versus a normal saline placebo in adult patients undergoing a decompressive lumbar laminectomy for spinal canal stenosis. Subjects enrolled in this study will receive a standardized general anesthetic that is consistent with our present clinical practice. The study participants will be randomized to receive both a perioperative bolus (2 mg/kg) and subsequent intravenous infusion (3 mg/kg/hr) of the amide local anesthetic lidocaine or a normal saline placebo at an equal volume per hour. The study infusion will be continued for 90 minutes after surgery. All patients will receive ample and adequate intravenous doses of an opioid (morphine sulfate) to reduce their pain intensity to acceptable levels. Pain intensity, opioid requirements, opioid-related side effects, and both the immediate and sustained rehabilitation pattern will be assessed. In addition to plasma lidocaine levels in the active drug group, plasma C-reactive protein, cortisol, and cytokine levels (e.g., IL-6, IL-10 and TNF-α) will be obtained at a series of perioperative time points in all study patients. Postoperative cytokine levels will also be measured in the surgical drainage fluid.

Eligibility Criteria:
Inclusion Criteria:

1. 19 years to 80 years of age
2. American Society of Anesthesiologists 1-3 status
3. Undergoing lumbar laminectomy between levels L1 and S1 for decompression of degenerative lumbar canal stenosis but without fusion or internal fixation performed

Exclusion Criteria:

1. American Society of Anesthesiologists 4 status
2. Previous spinal fusion surgery but patient may have undergone previous lumbar laminectomy or lumbar open discectomy
3. Morbid obesity (BMI \> 40)
4. Diagnosis of spinal metastatic cancer
5. Presence of a severe or systemic bacterial infection
6. Allergy to an amide local anesthetic or morphine sulfate
7. History of a seizure disorder
8. History of atrial or ventricular arrhythmia
9. History of autonomic dysfunction (e.g., dysautonomia of diabetes)
10. History of renal dysfunction, liver dysfunction or congestive heart failure
11. History of substance abuse disorder
12. History of major psychiatric disorder (e.g., depression, bipolar disorder, Axis II personality disorder, schizophrenia)
13. Chronic opioid use of greater than 100 mg/day of morphine equivalents within 30 days prior to surgery
14. Current use of a corticosteroid
15. Use of a non-steroidal anti-inflammatory drug (NSAID), including low dose aspirin within the past 5 days
16. Use of an arrhythmic drug within the past 7 days
17. Current administration of a known potent CYP1A2 inhibitor, including zileuton (Zyflo), ciprofloxacin, enoxacin or any other fluoroquinolone antibiotic, amiodarone, mexiletine, propafenone, verapamil, cimetidine (Tagamet), famotidine (Pepcid), oral contraceptives, acyclovir (Zovirax) and ticlopidine (Ticlid) (Horn \& Hansten, 2008).
18. Current administration of a known potent CYP3A4 inhibitor, including erythromycin, clarithromycin, azole antifungal (ketoconazole, fluconazole), verapamil, diltiazem, and grapefruit juice (Scuderi et al., 2006).
19. Pregnant females