Intra-operative lidocaine in the prevention of vomiting after elective tonsillectomy in children: A randomised controlled trial
The authors performed a double-blinded randomised controlled trial comparing intravenous lignocaine to placebo in reducing post-operative vomiting after tonsillectomy. Children, ASA 1 and 2, aged between 2 and 12 years of age scheduled for tonsillectomy (with or without adenoidectomy) were included. Children with a history of intellectual impairment, obesity, diabetes mellitus, use of any psychoactive and/or anti-emetic drugs within the 24 h prior to surgery, known congenital conduction disorders, gastro-oesophageal reflux, history of liver or renal insufficiency, seizures and a known allergy to lignocaine were excluded.
The 92 subjects were randomised to receive either intravenous lignocaine (1.5mg/kg bolus over 5 minutes followed by an infusion of 2mg/kg/hr until the end of the surgical procedure) or an identical volume and rate of 0.9% saline. The anaesthetist was blinded from the preparation of the trial drug and administered a standardised general anaesthetic technique with sevoflurane 2% in a mixture of nitrous oxide 50% and oxygen 50%, mivacurium 0.16mg/kg, fentanyl (up to 5 mcg/kg), dexamethasone 0.15mg and 25-30 mL/kg of Ringer’s lactate solution intraoperatively. All children were operated on using a standardised surgical technique. At the end of the case, a 1mL venous blood sample was drawn to measure the plasma concentration of lignocaine. At emergence, an orogastric tube was used to suction the stomach and reversal (atropine 20mcg/kg, neostigmine 50mcg/kg) was administered after evaluating residual neuromuscular blockade.
At least one episode of retching, vomiting or both during the first 24-hour post-operative period occurred in 28 of the 46 patients (60.8%) in the lignocaine group compared to 37 of 45 patients (82.2%) in the control group. In the lignocaine group, a mean total of 2.9 (SD 0.38) mg/kg was administered and the median lignocaine plasma concentration was 3.9mcg/mL (range: 0.87-4.88). After intention to treat analysis, the unadjusted odds ratio was 0.38 (95% CI, 0.15 – 0.97).
Take home message
This study concludes that intraoperative lignocaine administered as an infusion is a safe alternative for prevention of postoperative vomiting. However, this study doesn’t demonstrate a clinically significant reduction in incidence of vomiting, particularly compared to more commonly used antiemetics. In practice, we would be identifying how we could improve the incidence of vomiting of 60%. This is not to say that lignocaine does not have a role to play in our anaesthesia regimen. We know that lignocaine can reduce the incidence of perioperative respiratory adverse events and may also reduce the opioid requirements (and opioid-related side effects like nausea) in acute pain management. This study will not change what prophylactic antiemetics I administer to children having tonsillectomy, but may complement what I already do, knowing I can administer lignocaine safely.
Reviewed by: Dr Scott Ma