Lu 2013.

Methods	Double‐blind randomized controlled trial
Participants	Age (years, mean ± SD): Group CON = 50 ± 12, Group LID = 47 ± 13, Group DEZ = 47 ± 13 Gender (M:F): Group CON = 12:13, Group LID = 13:12, Group DEZ = 11:14 Inclusion criteria: age 16 years to 65 years, ASA I and II, scheduled for elective surgery under general anaesthesia were recruited for the study Exclusion criteria: patients with a history of renal or hepatic insufficiency, hypersensitivity to the study drugs, neurological or cardiovascular disease and patients with obesity, difficult airway, pregnant patients and patients on medication with pain modifying drugs Recruitment: 75 adult patients were randomly assigned (25 patients in each group) Setting: China
Interventions	Pretreatment alone A total of 75 patients were randomly assigned to one of the three groups, thus Group CON, received 2 ml of normal saline Group LID, received 2 ml of 2% lidocaine (40 mg) Group DEZ, received 2 ml of dezocine 2 mg as pretreatment Propofol was injected 1 min later
Outcomes	Pain intensity assessed on 4‐point scale 0 = no pain 1 = mild pain 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)	Low risk	"Group randomization was done according to the computer software generated random numbers"
Allocation concealment (selection bias)	Unclear risk	N/A
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	N/A written only double blind
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"An anaesthesiologist blinded to the intervention evaluated the pain level using a four‐point verbal rating scale (VRS) during injection of propofol."
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