Ortiz‐Gomez 2014.

Study characteristics
Methods	RCT
Participants	128 women Inclusion criteria: ASA I, elective caesarean under spinal anaesthesia Exclusion criteria: patient refusal to participate, contraindication to spinal anaesthesia, age < 20 or > 45 years, BMI > 30 kg/m², history of allergy or side effects to ondansetron Setting: Spain
Interventions	Comparison of different doses of prophylactic ondansetron with placebo Group 1: placebo 0.9% saline 10 mL Group 2: 2 mg ondansetron with 0.9% saline to total volume of 10 mL Group 3: 4 mg ondansetron with 0.9% saline to total volume of 10 mL Group 4: 8 mg ondansetron with 0.9% saline to total volume of 10 mL The above 10 mL preparation was injected IV over 60 s, 5 min before the spinal anaesthesia was performed All women received the same IV cannulation, monitoring, spinal anaesthetic technique with dose adjusted according to height, and 8 mL/kg of colloid coloading Hypotension was treated with IV ephedrine 10 mg, or phenylephrine 50 μg if maternal heart rate > 95 beat/min Bradycardia was treated with IV atropine 0.01 mg/kg
Outcomes	Maternal: incidence of hypotension, adverse effects, need for atropine or ephedrine or phenylephrine
Notes	Hypotension defined as SBP < 75% of baseline Bradycardia was defined as heart rate < 45 beat/min
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomised by local statistical department
Allocation concealment (selection bias)	Low risk	Ondansetron/placebo syringes were prepared by the anaesthetic nurse with no label indicating the group allocation
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blinded
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double‐blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	None reported
Selective reporting (reporting bias)	Low risk	None apparent
Other bias	Low risk	None apparent