Das Neves 2010.

Study characteristics
Methods	RCT
Participants	120 women Inclusion criteria: physical status ASA I, with an indication for elective CS, singleton term pregnancy Exclusion criteria: history of hypertension or pregnancy‐induced hypertension, cardiovascular or cerebrovascular disease, fetal abnormalities, history of hypersensitivity to the drugs used in the study, and contraindications to spinal block Setting: Brazil
Interventions	Phenylephrine: prophylactic infusion versus therapeutic dosing Group 1: continuous IV infusion of phenylephrine, using a 1‐channel "Baxter" volumetric infusion pump (containing a solution of 10 mL of NS with 10 mg phenylephrine (100 μg/mL)), at 0.15 μg/kg/min, which was started immediately after the spinal block Group 2: a single dose of phenylephrine, 50 μg IV, administered immediately after the spinal block.  Baxter volumetric infusion pump connected, containing 100 mL NS Group 3: a single dose of phenylephrine, 50 μg IV, administered in case of hypotension, defined as a fall in SBP and/or DBP of up to 20% of mean baseline levels.  Baxter volumetric infusion pump connected, containing 100 mL NS All women received a standardised spinal anaesthetic technique and dose followed by a standardised crystalloid infusion and standardised positioning. Hypotension treatment involved a bolus of 30 μg of phenylephrine IV repeated every 2 min if a drop in BP > 20% that was not controlled with the therapeutic regimen used. Bradycardia was treated when associated with hypotension with 0.5 mg of atropine IV.
Outcomes	Maternal: hypotension; reactive hypertension; bradycardia; nausea and vomiting Neonatal: Apgar score < 8 at 5 min
Notes	Hypotension defined as a drop in SBP and/or DBP > 20% of mean baseline levels Reactive hypertension defined as BP 20% > mean baseline levels after the use of the vasopressor Bradycardia defined as heart rate lower than 50 bpm
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer‐generated numbers
Allocation concealment (selection bias)	Unclear risk	Sequential sealed envelopes
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	"Double blind."  Patients, and physicians responsible for collecting and analysing the data were blinded; anaesthetist administering the anaesthesia was not blinded.  This anaesthetist was not involved in data collection and analysis.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Those collecting and analysing the data were blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	No losses to follow‐up occurred
Selective reporting (reporting bias)	Low risk	None apparent
Other bias	Unclear risk	No apparent sources of other bias