title: A dose-response meta-analysis of prophylactic intravenous ephedrine for the prevention of hypotension during spinal anesthesia for elective cesarean delivery.
abstract: We systematically reviewed available studies to determine the dose-response characteristics of prophylactic i.v. ephedrine for the prevention of hypotension during spinal anesthesia for cesarean delivery. We searched for randomized controlled trials (RCTs) or cohort studies-obtained through MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, and reference lists of published articles-in which two or more different doses of prophylactic i.v. ephedrine were used to prevent hypotension during spinal anesthesia for cesarean delivery. Four RCTs and one cohort study were found (total n = 390). There was a significant dose-response relationship in the RCTs pooled for hypotension (slope = -0.0128; 95% confidence interval [CI], -0.0213 to -0.0044), hypertension (slope = 0.0563; 95% CI, 0.0235 to 0.0892), and umbilical arterial pH (slope = -0.03; 95% CI, -0.05 to 0.00). The efficacy of ephedrine for preventing hypotension was small. At 14 mg, the number-needed-to-treat was only 7.6 (95% CI, 4.8-21.1), and this was the same as the number-needed-to-harm (7.6; 95% CI, 3.7-23.4). At larger doses, the likelihood of causing hypertension was actually more than that of preventing hypotension, and there was also a minor decrease in umbilical arterial pH.
  
  
  CONCLUSIONS
  The authors performed a systematic review of dose-response studies of i.v. bolus ephedrine for preventing hypotension during spinal anesthesia for cesarean delivery. Prophylactic ephedrine cannot be recommended. The efficacy is poor at smaller doses, whereas at larger doses, the likelihood of causing hypertension is actually more than that of preventing hypotension.
authors.affiliation: Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong, China.
authors.forename: Anna
authors.initials: A
authors.lastname: Lee
authors.forename: Warwick D
authors.initials: WD
authors.lastname: Ngan Kee
authors.forename: Tony
authors.initials: T
authors.lastname: Gin
mesh_terms: D000328:Adult; D000775:Anesthesia, Spinal; D001034:Apgar Score; D001794:Blood Pressure / Q000187:drug effects; D002585:Cesarean Section; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D004809:Ephedrine / Q000008:administration & dosage* / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007022:Hypotension / Q000517:prevention & control*; D007275:Injections, Intravenous; D007431:Intraoperative Complications / Q000517:prevention & control*; D011247:Pregnancy; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D014662:Vasoconstrictor Agents / Q000008:administration & dosage* / Q000627:therapeutic use*
chemical_list: D014662:Vasoconstrictor Agents; D004809:Ephedrine