Opioid sparing analgesia: Continuous intraoperative infusion of dexmedetomidine versus lidocaine for laparoscopic cholecystectomy, a randomized double-blind clinical trial.

Postoperative pain represents one of the most common complaints following surgeries. Despite advances in modern medicine, pain following surgical procedures is still a challenge for anesthetists, though significant progress made over the past decades. The mechanism of pain following laparoscopic procedures is thought to be multifactorial. The main causes of pain after laparoscopic cholecystectomy (LC) are pain from the incision site, pneumoperitoneum and cholecystectomy. Clinicians using different methods for analgesia after LC. like non-steroidal anti-inflammatory drugs, intraperitoneal local anesthetics, local anesthetics applied to the wound site, removal of the insufflation gas, paravertebral block (PVB), and epidural block. To date, the mainstay of management has been the administration of exogenous opioids such as morphine or fentanyl. However, pain is not always fully relieved by such agents, and often patients develop tolerance to them. The ever-increasing doses of opioids are clearly not without their adverse effects. In addition to that, many patients and even some clinicians wrongly believe that addiction can be inevitable after administration of opioids. Dexmedetomidine is an alpha 2-adrenergic agonist which is a relatively new drug used for procedural sedation. It has sedative and anxiolytic effects and is known for its analgesic potential owing to a reduction of sympathetic tone. Dexmedetomidine has dose-dependent effects, ranging from minimal to deep sedation. Moreover, except at doses that cause very deep sedation or general anesthesia, the sedation is reversible. These are unique properties among the sedative medications in common use. Dexmedetomidine does not impair the respiratory drive per se and seldom causes apnea. However, it has been shown to impair the respiratory responses to hypoxia and hypercapnia and can cause hemodynamic effects such as hypertension, hypotension and bradycardia. Systemic lidocaine has centrally and peripherally analgesic, anti-hyperalgesic and anti-inflammatory effects with reduced side-effects especially if used with appropriate dose. Recently, intravenous lidocaine infusion is considered a part of analgesic therapy regimen that decreases postoperative opioid requirements and enhances convalescence after major surgeries. Dexmedetomidine and lidocaine are common adjuvant medicine anesthetics during operation for the sedative and analgesic properties. Besides, some studies have proved that both are effective in relieving postoperative pain in adults. However, there are very limited studies comparing the effects of the two adjuvant analgesics on postoperative pain in patients undergoing laparoscopic cholecystectomy (LC).

Inclusion Criteria:

• Patient's status ASA status-I and II.
• Patients age above 18 years old.
• Patients scheduled for laparoscopic cholecystectomy.

Exclusion Criteria:

• Patient refusal.
• Patients with known allergy to dexmedetomidine or lidocaine.
• Patients with significant hepatic dysfunction.
• Patients with severe renal disease.
• Patients with chronic pain.
• Regular use analgesics, antidepressants or opioids in last month.
• Any known convulsive disorder.
• Significant heart disease.
• Morbid obesity (BMI>35).
• Patients with autoimmune disease
• Patients on corticosteroid therapy
• Pregnancy
• Breast feeding
• Woman under hormonal treatment