Zahedi 2009.

Methods	Double‐blind randomized controlled trial
Participants	Age (years, mean ± SD): Group NS = 28.9 ± 7.4, Group L = 29.7 ± 6.8, Group K50 = 29.4 ± 7.8, Group K75 = 29.7 ± 8.8, Group K100 = 30.7 ± 6.6 Gender (M:F): Group NS = 55:45, Group L = 51:49, Group K50 = 48:52, Group K75 = 56:44, Group K100 = 49:51 Inclusion criteria: age 18 years to 40 years old, ASA I‐II, elective strabismus surgery Exclusion criteria: patients taking sedatives or analgesics in the past 24 hours before surgery and those with history of allergic reactions to anaesthetic drugs, neurologic or cardiovascular disease and pregnant patients Recruitment: 500 adult patients randomly assigned (100 in each group) Setting: Iran
Interventions	Pretreatment alone Patients were randomly allocated into five groups: patients received normal saline (Group NS) lidocaine 1 mg/kg (Group L) different doses of ketamine, 50 μg/kg, 75 μg/kg or 100 μg/kg (Group K50, K75, K100 respectively), pretreated immediately before the injection of 2.5 mg/kg propofol Each patient’s pain scores were measured at five‐second intervals by a blinded anaesthesiologist
Outcomes	Pain intensity assessed on 4‐point scale 0 = none 1 = mild pain 2 = moderate pain 3 = severe pain Outcomes reported and used Incidence of high‐intensity pain Incidence of pain Adverse effects Outcomes sought but not reported 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	N/A
Allocation concealment (selection bias)	Unclear risk	N/A
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Study drugs were diluted with NS 0.9% up to 5cc and were prepared by an investigator not involved in drug injection or assessment of patients' responses."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"A blinded anaesthesiologist before the administration of propofol asked the patient to rate any sensation of pain."
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

Abbreviations used in tables:
 ASA = American Society of Anesthesiologists physical status classification
 ENT = Ear Nose Throat
 hr = hour
 kg = kilograms
 LCT = Long‐chain triglyceride
 MCT = Medium‐chain triglyceride
 μg = micrograms
 mg = milligrams
 ml = millilitres
 min = minutes
 n o = number
 N/A = not available
 NSAIDs = Non‐steroidal antiinflammatory drugs
 sec = seconds
 yr = years