title: Haemodynamic effects of glycopyrrolate pre-treatment before phenylephrine infusion during spinal anaesthesia for caesarean delivery.
abstract: BACKGROUND
  Phenylephrine given during spinal anaesthesia for caesarean delivery often induces a decrease in heart rate which may decrease cardiac output. Anticholinergic drugs may be given to attenuate this effect but may also cause more labile blood pressure. This study evaluated the effects of glycopyrrolate pre-treatment on non-invasively measured cardiac output and accuracy of blood pressure control.
  
  
  METHODS
  At induction of spinal anaesthesia for caesarean delivery, 104 patients randomly received intravenous glycopyrrolate 4μg/kg or saline placebo. Systolic blood pressure, measured at 1-min intervals, was maintained near baseline using closed-loop feedback computer-controlled phenylephrine infusion with crystalloid cohydration. Cardiac output and stroke volume were measured using suprasternal Doppler ultrasonography at baseline and 5-min intervals for 20min. Blood pressure control was assessed using performance error calculations.
  
  
  RESULTS
  Eleven patients were excluded. Patients who received glycopyrrolate (n=45) had greater cardiac output over time (P<0.001), greater heart rate over time (P<0.001), similar stroke volume over time (P=0.95), and lower median phenylephrine infusion rate (P=0.006) compared with control (n=48). There was no difference in the incidence of hypotension between groups. Analysis of blood pressure control showed greater positive bias, greater inaccuracy and greater wobble in the glycopyrrolate group (all P<0.05). Neonatal outcome was similar between groups.
  
  
  CONCLUSIONS
  Glycopyrrolate 4μg/kg given at the start of a phenylephrine infusion increased heart rate and cardiac output but also decreased accuracy of blood pressure control, increased the incidence of hypertension and caused an increased incidence of dry mouth postoperatively compared with control.
authors.affiliation: Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China.
authors.forename: W D
authors.initials: WD
authors.lastname: Ngan Kee
authors.forename: S W Y
authors.initials: SW
authors.lastname: Lee
authors.forename: K S
authors.initials: KS
authors.lastname: Khaw
authors.forename: F F
authors.initials: FF
authors.lastname: Ng
mesh_terms: D000328:Adult; D000465:Algorithms; D000773:Anesthesia, Obstetrical / Q000379:methods*; D000775:Anesthesia, Spinal / Q000379:methods*; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D002585:Cesarean Section / Q000379:methods*; D004311:Double-Blind Method; D005260:Female; D006024:Glycopyrrolate / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology*; D011247:Pregnancy; D018401:Sample Size; D013318:Stroke Volume / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D018727:Muscarinic Antagonists; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D006024:Glycopyrrolate