Ansari 2011.

Study characteristics
Methods	RCT
Participants	128 women Inclusion criteria: women with a normal singleton pregnancy at 37 weeks' gestation or more scheduled for elective CS Exclusion criteria: ASA grade III or more; height < 150 cm or > 180 cm; body mass < 60 kg or > 100 kg; pre‐eclampsia; known fetal abnormality; or any other contraindication to spinal anaesthesia Setting: United Arab Emirates
Interventions	Phenylephrine 50 μg versus 100 μg infusion Group 1: phenylephrine 50 μg/mL infusion Group 2: phenylephrine 100 μg/mL infusion Phenylephrine infusion was commenced immediately after spinal anaesthesia in conjunction with standardised IV coload with warm Hartmann's solution. Initial phenylephrine rate of 60 mL/h for the first 3 min and stopped if SBP was > 120% of the baseline. After the first 3 min, the infusion was continued at the same rate if SBP was between 80% and 100% of baseline, until the time of giving birth; infusion was discontinued if the SBP was more than 100% of baseline value. All women received standardised aspiration prophylaxis and standardised spinal anaesthetic technique and dose. Hypotension requiring intervention: rescue dose of phenylephrine 50 μg if BP decreased to < 80% baseline for 2 consecutive readings, despite phenylephrine infusion. Bradycardia requiring intervention: if bradycardia without hypotension, phenylephrine infusion was discontinued for 1 min; if bradycardia developed with hypotension, IV glycopyrronium 200 μg was administered.
Outcomes	Maternal: BP; hypotension; hypertension; bradycardia; total dose of phenylephrine; nausea and vomiting Neonatal: Apgar scores at 1 min and 5 min; umbilical arterial pH and gases
Notes	Hypotension defined as SBP < 80% baseline Hypertension defined as SBP > 120% baseline Bradycardia defined as heart rate < 50 bpm
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Randomised" – no further details reported
Allocation concealment (selection bias)	Unclear risk	"Closed similar" envelopes
Blinding of participants and personnel (performance bias) All outcomes	Low risk	An anaesthetist who was not involved in case management prepared a 20 mL syringe for phenylephrine infusion with the designated concentration; both women and the anaesthetist in charge of the case were blinded to the concentration of phenylephrine in the syringe
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Not reported, but likely in view of the above.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	11/128 lost to follow‐up (not reported by assigned group): inadequate block and repeat subarachnoid injection required (n = 2) trial design not strictly followed (n = 4) umbilical blood gas results had technical problems (n = 5)
Selective reporting (reporting bias)	Low risk	Most expected outcomes were reported.
Other bias	Unclear risk	Some suggestion of imbalance in randomisation and/or differential losses to follow‐up (54 and 63 women analysed in each group)