Yektas 2011.

Methods	RCT, 9 parallel groups
Participants	Number: 180 participants (9 × 20) Country: Turkey Surgery: inguinal surgery Age: 20 to 30 years ASA: I Other inclusion criteria: spinal anaesthesia Exclusion criteria: drug abuse, recall of pain at earlier surgery, need for additional sedation at earlier surgery, cerebrospinal fluid could not be obtained after 3 attempts, education level below primary school
Interventions	Control group: 15 mg hyperbaric bupivacaine and 0.5 mL physiological serum intrathecally vs In the other groups, serum was replaced with the following to a total volume of 3.5 mL: Hyperbaric bupivacaine 2.5 mg vs Ketamine 12.5 mg vs Fentanyl 25 µg vs Sufentanil 2.5 µg vs Dexmedetomidine 2 µg vs Neostigmine 250 µg vs Midazolam 500 µg vs Droperidole 1.25 mg
Outcomes	Intraoperative and postoperative side effects Time to first pain
Notes	Only abstract of conference paper available. Study authors contacted for additional information, awaiting reply

RCT: randomized controlled trial; ASA: American Society of Anesthesiologists Physical Status 1 to 6, where 1 = Healthy person, 2 = Mild systemic disease, 3 = Severe systemic disease, 4 = Severe systemic disease that is a constant threat to life, 5 = A moribund person who is not expected to survive without the operation, 6 = A declared brain‐dead person whose organs are being removed for donor purposes; PCA: patient‐controlled analgesia; PACU: post‐anaesthesia care unit; BMI: body mass index