title: Closed-loop double-vasopressor automated system to treat hypotension during spinal anaesthesia for caesarean section: a preliminary study.
abstract: Hypotension occurs in most caesarean sections under spinal anaesthesia, necessitating vasopressor administration. However, the optimal dosing regimen remains unclear. We have developed a novel vasopressor delivery system that automatically administers phenylephrine or ephedrine based on continuous non-invasive blood pressure monitoring. This prospective cohort study recruited 55 healthy women under standardised spinal anaesthesia with 2.2 ml hyperbaric bupivacaine 0.5%, 15 μg fentanyl and 100 μg morphine. A 50-μg phenylephrine bolus was given at 1-min intervals when systolic blood pressure fell below 90% of baseline, and a 4-mg ephedrine bolus was given when hypotension developed with bradycardia (heart rate <60 beats.min(-1) ). Systolic blood pressure was within 20% of baseline in 88% of all measurements. Six patients (11%) had one or more measurements above 120% of baseline (1% of all measurements), whereas 36 (65%) had at least one reading below 80% of baseline (11% of total measurements). The system maintained systolic blood pressure at a mean (SD) of -9.1 (7.0)% below baseline, with 5.4 (2.5)% fluctuation. Two patients (4%) experienced pre-delivery nausea. All 5-min Apgar scores were 9.
authors.affiliation: Department of Women's Anaesthesia, KK Women's and Children's Hospital, Singapore.
authors.forename: A T H
authors.initials: AT
authors.lastname: Sia
authors.forename: H S
authors.initials: HS
authors.lastname: Tan
authors.forename: B L
authors.initials: BL
authors.lastname: Sng
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid; D000773:Anesthesia, Obstetrical / Q000009:adverse effects*; D000775:Anesthesia, Spinal / Q000009:adverse effects*; D000779:Anesthetics, Local; D002045:Bupivacaine; D002585:Cesarean Section; D015331:Cohort Studies; D016503:Drug Delivery Systems / Q000379:methods*; D004809:Ephedrine / Q000008:administration & dosage; D005260:Female; D005283:Fentanyl; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007022:Hypotension / Q000139:chemically induced / Q000188:drug therapy*; D008875:Middle Aged; D009020:Morphine; D010656:Phenylephrine / Q000008:administration & dosage; D011247:Pregnancy; D011446:Prospective Studies; D014662:Vasoconstrictor Agents / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D009020:Morphine; D004809:Ephedrine; D005283:Fentanyl; D002045:Bupivacaine