Dahlgren 2007.

Study characteristics
Methods	RCT
Participants	55 women presenting for elective CS Inclusion criteria: healthy women with term singleton normal pregnancies Setting: Sweden
Interventions	Colloid versus crystalloid preload Group 1: colloid group: 20 mL of 15% dextran 1, followed by 1000 mL IV infusion of 3% dextran 60.  This solution was administered during 20 min immediately preceding intrathecal injection.  Group 2: crystalloid group: 20 mL IV injection of 0.9% saline, followed by 1000 mL IV infusion of acetated Ringer's solution.  This solution was administered during 20 min immediately preceding intrathecal injection.  All women received standardised fasting protocol, no premedication and a standardised spinal anaesthetic technique and dose. Hypotension requiring intervention was managed with ephedrine 5 mg if SBP dropped below 100 mmHg, and repeated as required.
Outcomes	Maternal: hypotension – overall, clinically significant or severe Criteria for rescue: if the woman developed discomfort associated with a decrease in SBP of at least 20% from baseline, even if it was above 100 mmHg
Notes	'Overall' hypotension defined as a fall in systolic pressure below 100 mmHg 'Clinically significant' hypotension defined as hypotension associated with maternal discomfort (nausea, retching/vomiting, dizziness or chest symptoms) 'Severe' hypotension defined as a reduction of the SAP below 80 mmHg
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Randomly allocated" – method not specified
Allocation concealment (selection bias)	Unclear risk	Sealed envelope
Blinding of participants and personnel (performance bias) All outcomes	Low risk	'Double‐blind'. The woman, the anaesthesiologist and all other personnel in the operating room were unaware of the study group. The study solutions were prepared and administered by an anaesthetic nurse who was not otherwise involved in the care of the patient, and were covered by a non‐transparent plastic bag. The anaesthesiologist did not enter the operating room until the study solution had been given.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	All personnel were blinded to treatment allocation, except for the anaesthetic nurse who prepared the solutions (who was not involved in the care of the patient).
Incomplete outcome data (attrition bias) All outcomes	Low risk	2/55 excluded due to protocol violation (1 was given ephedrine despite a normal BP and the other could not go through the SST because of leg muscle spasm). Not specified which groups they were from
Selective reporting (reporting bias)	Low risk	Only maternal outcome reported was hypotension; no infant outcomes were reported
Other bias	Low risk	No apparent sources of other bias