Das 2012.

Study characteristics
Methods	Prospective, observer‐blinded, parallel‐arm randomised controlled trial (RCT) wherein 1 arm received conventional general anaesthesia (GA) and the other arm received multi‐injection thoracic paravertebral (PVB) anaesthesia for patients undergoing breast cancer surgery
Participants	60, ASA physical status I and II, 18 to 65 years old, female; patients scheduled to undergo unilateral breast surgery with or without axillary clearance were enrolled in the study
Interventions	PVB group (n = 29) Pre‐medication: all patients received 10 mg oral diazepam the evening before surgery Sedation for block: all patients were administered incremental doses of intravenous midazolam (up to a maximum of 0.06 mg/kg) along with 2 mcg/kg intravenous fentanyl All patients were administered unilateral, multi‐injection paravertebral block from T3 to T6 with 5 mL 0.5% bupivacaine injected at each level on the side of surgery with the patient in the lateral position using the landmark approach PVB failure in 1 patient resulted in the patient being administered GA and excluded from analysis Sedation during surgery: all patients were administered 30 to 70 mcg/kg/min propofol intravenous infusion. Intermittent boluses of 25 mcg intravenous fentanyl and 10 mg intravenous propofol were administered on increase in mean arterial pressure (MAP) 20% above baseline GA group (n = 30) Pre‐medication: all patients received 10 mg oral diazepam the evening before surgery as well as intravenous midazolam (0.04 to 0.06 mg/kg) just before surgery Induction was carried out with intravenous fentanyl (2 mcg/kg), followed by propofol (2 mg/kg), atracurium (0.5 mg/kg), and endotracheal intubation. Patients also received intramuscular diclofenac sodium and repeat boluses of fentanyl 25 mcg and propofol 10 mg on increase in mean arterial pressure (MAP) 20% above baseline
Outcomes	Primary outcome • Comparison of the efficacy of thoracic PVB block to GA for breast surgery with duration of postoperative pain relief the primary endpoint (time from last suture to first analgesic administered when VAS ≥ 4) Secondary outcomes • Total dose of analgesic (tramadol and diclofenac sodium) consumed in the first 24 hours • Number of patients experiencing PONV • Any complications • Quality of anaesthesia judged by surgeon • Satisfaction with anaesthetic technique judged by patient
Notes	No external funding received
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of randomisation has not been specified
Allocation concealment (selection bias)	Low risk	Patients were allocated using the sealed envelope technique
Blinding of participants and personnel (performance bias) All outcomes	High risk	Blinding was not possible because of the nature of interventions (1 group got GA and the other got PVB)
Blinding of outcome assessment (detection bias) All outcomes	Low risk	VAS was assessed by a resident not involved in the study. Patient anaesthesia records were not made available to the resident for the first 24 hours
Incomplete outcome data (attrition bias) All outcomes	Low risk	Only 1 patient in the PVB group was excluded because of inadequate block that necessitated conversion to GA
Selective reporting (reporting bias)	Low risk	Complications were looked for and reported
Other bias	Low risk	No other risk of bias was apparent