Karasawa 2000.

Methods	Randomized controlled trial
Participants	Age (years, mean ± SD): Group S = 51 ± 3, Group F = 58 ± 2, Group L = 49 ± 3 Gender (M:F): Group S = 28:22, Group F = 25:25, Group L = 27:23 Inclusion criteria: ASA I‐II, elective surgery Exclusion criteria: N/A Recruitment: 150 adult patients randomly assigned (50 in each group) Setting: Japan
Interventions	Admixture Group S received 5 ml of NSS followed by propofol mixed with 0.4 ml of NSS Group F received 5 ml of LFP 50 mg followed by propofol mixed with 0.4 ml of NSS Group L received 5 ml of NSS followed by propofol premixed with 0.4 ml of 10% lidocaine (40 mg)
Outcomes	Pain intensity assessed on 4‐point scale 0 = no pain 1 = mild pain (uncomfortable or a little painful) 2 = moderate pain 3 = severe pain Outcomes reported and used Incidence of high‐intensity pain Incidence of pain Outcomes sought but not reported Adverse effects Patient satisfaction
Notes	Period of the study: dates not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Patients were randomly allocated into three groups."
Allocation concealment (selection bias)	Unclear risk	N/A
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	N/A
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"Pain score were asked by anaesthesiologist who was unaware of the group of patient."
Incomplete outcome data (attrition bias) All outcomes	Low risk	No withdrawals
Selective reporting (reporting bias)	Unclear risk	N/A
Other bias	Low risk	The study appears to be free of other sources of bias