Kang 2011.

Methods	Randomized, placebo‐controlled trial. Participants, personnel, and outcome assessors were blinded. This study evaluated the effectiveness of intravenous lidocaine to reduce postoperative pain in inguinal herniorrhaphy patients. The study was conducted in Korea from December 2009 to September 2010.
Participants	Number assessed for eligibility: 87 Number randomized: 64 → 32:32 Number analysed: 32:32 Inclusion criteria Inguinal herniorrhaphy patients aged 18 to 65 years. Exclusion criteria Patients who weighed < 45 kg or > 100 kg, had severe underlying cardiovascular (especially atrioventricular block), renal or hepatic disease and were allergic to local anaesthetics were excluded. Patients were also excluded if they had received opioids or non‐steroidal anti‐inflammatory drugs within the previous one week or were taking these drugs chronically as pain treatment. Baseline details Experimental group (n = 32) Median age (years): 35.5 M = 69%, F = 31% Median weight (kg): 67 ASA I/II/III: 21:/6:/5 Duration of anaesthesia (min): 66.03 Main surgical procedure: unilateral inguinal hernia surgery Control group (n = 32) Median age (years): 34.5 M = 63%, F = 37% Median weight (kg): 66 ASA I/II/III: 25:4:3 Duration of anaesthesia (min): 63.38 Main surgical procedure: unilateral inguinal hernia surgery
Interventions	Experimental group (32 patients) The lidocaine group received an intravenous bolus of 1.5 mg/kg lidocaine 2 min before orotracheal intubation followed by a continuous infusion of 2 mg/kg/hr. The intravenous infusion of lidocaine was started immediately and continued during the operation. Control group (32 patients) Control patients received an intravenous normal saline bolus injection followed by infusion of normal saline.
Outcomes	The primary endpoint of the study was the VAS pain score 2 hrs after surgery. Dichotomous Postoperative nausea and vomiting during 48 hrs after surgery Continuous Pain score (VAS 0 to 100) during rest at 2 hrs, 4 hrs, 8 hrs, 12 hrs, 24 hrs, and 48 hrs, (data presented graphically) Fentanyl consumption (µg/hr), 0 to 2 hrs, 2 to 4 hrs, 4 to 8 hrs, 8 to 12 hrs, 12 to 24 hrs, 24 to 48 hrs and total dose 0 to 48 hrs in µg (data presented graphically) Frequency of button pushes, 0 to 2 hrs, 2 to 4 hrs, 4 to 8 hrs, 8 to 12 hrs, 12 to 24 hrs, 24 to 48 hrs and total number of button pushes 0 to 48 hrs (data presented graphically) Length of hospital stay (days, presented as median with IQR) First flatus (presented as median with IQR) Time to start a regular diet (days, presented as median with IQR)
Notes	Small trial sample size (< 200 patients) Power analysis performed (pain score, n = 32) Medication "The mode of post‐operative analgesia was continuous infusion of 0.1 µg/kg per hr fentanyl plus, by pushing a button on the PCA system, on‐demand release of a 0.1 µg/kg bolus (total regimen of 100 ml of fentanyl); the PCA had a lockout period of 15 min. In the case of a persistent VAS pain score > 30 mm, an additional rescue analgesia dose of 50 µg fentanyl was injected intravenously by an investigator to lower the VAS pain score to < 30 mm. Post‐operative nausea and vomiting were treated with 4 mg intravenous ondansetron as required." Anaesthesia The anaesthesia regime was standardized in both groups. Funding "This research was supported by Chung‐Ang University Research Grants in 2010."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "randomization was based on computerized random‐number generation."
Allocation concealment (selection bias)	Unclear risk	Quote: "the group assignments were kept in a set of sealed envelopes, each bearing only the case number on the outside."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "all patients, surgeons, anaesthesiologists and the investigator collecting data were unaware of patient´s group assignments."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "all patients, surgeons, anaesthesiologists and the investigator collecting data were unaware of patient´s group assignments."
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Dropout rate (experimental/control): 9%:13% Quote: "one patient in the control group was excluded from the study at the conclusion of the operation as meperidine was required to treat post‐operative shivering. Another patient who fit the inclusion criteria replaced this patient." We assume that the replacing patient was not randomized based on the description (no response from the authors upon request). Replacement may have an impact on relevant outcomes.
Selective reporting (reporting bias)	Unclear risk	There is no reference to a trial registry and no published study protocol.
Other bias	Low risk	The study appears to be free of other sources of bias.