Intraoperative Lidocaine Infusion vs. Esmolol Infusion for Postoperative Analgesia in Laparoscopic Cholecystectomy: a Randomized Clinical Trial

Postoperative pain after abdominal surgery includes many forms of distress, such as spontaneous pain at rest; pain during movement, including that of respiration; and visceral pain arising from damage to internal organs during surgery. Acute pain after laparoscopic cholecystectomy is complex in nature. The pain pattern does not resemble pain after other laparoscopic procedures, suggesting that analgesic treatment might be procedure specific and multimodal. Three components have been described: incisional pain as dominant, visceral deep pain, and shoulder referred pain. Opioids are most commonly used for postoperative analgesia in laparoscopic cholecystectomy. However, they can be associated with many side effects and delayed discharge. In addition, opioids do not offer the quality of postoperative pain relief that one would expect, probably because of the pain specific to laparoscopic cholecystectomy. A single agent is unlikely to treat all three types of pain. Therefore a multimodal approach will be required.

Low-dose IV lidocaine is easy to administer, has well-established analgesic, anti-hyperalgesic, and anti-inflammatory effects, and has minimal toxicity in commonly studied doses (typically 1.5-3 mg/kg/h). Because postoperative pain is to a large extent an inflammatory phenomenon, administration of systemic local anesthetics, which have inflammatory modulatory properties, could significantly reduce pain and therefore allow more rapid discharge. Lidocaine has an excellent safety record when administered by low-dose infusion. In addition, intravenous lidocaine is an effective modality for treating visceral pain.

Esmolol has been proposed as an alternative to intraoperative use of opioids, and found to facilitate the fast-tracking process and speed home-readiness of patients undergoing outpatient surgery. The various mechanisms of opioids dose sparing with concomitant use of β-adrenergic antagonist have been proposed from time to time such as suppression of stress hormones and pro-inflammatory cytokines, alteration of hepatic drug metabolism, activation of G-coupled proteins in cell membrane, central analgesia and so on but nothing conclusive has been established as yet.

After pre operative evaluation, patients will be premedicated with oral diazepam (0.1-0.2 mg/kg) at the night before and 2 hours before surgery. Informed consent will be obtained from all patients. Patients will be instructed during pre-anaesthetic visit about the use of the visual analogue scale (0-10 cm) where 0 is no pain and 10 is worst imaginable excruciating pain. They will also be informed that they will be asked their pain (VAS score) with its character during first 24 hrs after the surgery.

Both the patient and the investigator observing the outcome will be blinded about assignment of patient group during the study. The investigator will not enter the operating room but will be responsible for data collection in post operative period and data analysis. On arrival of patients in the preoperative holding area, they will be randomly assigned into any of two groups using computer generated random number. Details of group assignment and case number will be kept in a set of sealed opaque envelope. The anesthesia staff will open the envelope and prepare drugs accordingly. The attending anesthesiologist will not be involved in the data collection and analysis, and will follow the standard general anaesthesia protocol during the study.