title: Changes in blood pressure and cardiac output during cesarean delivery: the effects of oxytocin and carbetocin compared with placebo.
abstract: BACKGROUND
  Little is known about maternal hemodynamics after Cesarean delivery. Uterine contractions may increase cardiac output. Oxytocin is the first-line treatment for uterine atony, although the effects of the long-acting oxytocin analogue carbetocin are comparable with that of oxytocin. The authors analyzed the effects of i.v. oxytocin 5 U, carbetocin 100 µg, and placebo on hemodynamics, uterine tone, adverse events, and blood loss after Cesarean delivery.
  
  
  METHODS
  This was a randomized, double-blinded, placebo-controlled, parallel-group comparison of carbetocin and oxytocin after elective Cesarean delivery of singletons under spinal anesthesia (n = 76). Continuously measured invasive systolic arterial pressure was the primary outcome measure.
  
  
  RESULTS
  The mean systolic arterial pressure decrease was 28 mmHg (95% CI, 22-34) after oxytocin and 26 mmHg (95% CI, 20-31) after carbetocin. The decrease was greatest after 80 (95% CI, 71-89) and 63 s (95% CI, 55-72), respectively (P = 0.006). The differences were nearly undetectable after 2.5 min, although the effect of carbetocin was slightly greater than placebo (P < 0.001). The group differences in systolic arterial pressure decreased over 5 min and were gone at 1 h. Heart rate and cardiac output increased in all three groups. Stroke volume increased after oxytocin and carbetocin but was unchanged after placebo.
  
  
  CONCLUSIONS
  The hemodynamic side effects of oxytocin 5 U and carbetocin 100 µg were comparable. The lack of an increase in stroke volume in the placebo group challenges the theory that uterine contraction causes autotransfusion of uterine blood, leading to an increase in preload.
authors.affiliation: Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway. l.a.rosseland@medisin.uio.no
authors.forename: Leiv Arne
authors.initials: LA
authors.lastname: Rosseland
authors.forename: Tor Hugo
authors.initials: TH
authors.lastname: Hauge
authors.forename: Guro
authors.initials: G
authors.lastname: Grindheim
authors.forename: Audun
authors.initials: A
authors.lastname: Stubhaug
authors.forename: Eldrid
authors.initials: E
authors.lastname: Langesæter
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects*; D002302:Cardiac Output / Q000187:drug effects*; D002585:Cesarean Section; D004311:Double-Blind Method; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D010120:Oxytocics / Q000009:adverse effects*; D010121:Oxytocin / Q000009:adverse effects* / Q000031:analogs & derivatives*; D011247:Pregnancy
chemical_list: D010120:Oxytocics; D010121:Oxytocin; C020731:carbetocin