Overpressure isoflurane at Caesarean section: a study of arterial isoflurane concentrations

• Published in: British journal of anaesthesia : BJA Vol. 72; no. 1; pp. 122 - 124
• Main Authors: McCRIRRICK, A., EVANS, G.H., THOMAS, T.A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.1994; Oxford University Press
• Subjects: Adolescent; Adult; Anaesthesia: obstetric; Anaesthetics; Anaesthetics, volatile isoflurane; Anesthesia, General; Anesthesia, Obstetrical; Anesthetics. Neuromuscular blocking agents; Awareness; Biological and medical sciences; Cesarean Section; Dose-Response Relationship, Drug; Female; Humans; Infusions, Intravenous; Isoflurane - administration & dosage; Isoflurane - blood; Medical sciences; Neuropharmacology; Pharmacology. Drug treatments; Pregnancy; Proprioception - drug effects; Reflex - drug effects; Time Factors; volatile isoflurane; Anaesthesia: obstetric; Anaesthetics, volatile isoflurane; Volatile compound; Human; General anesthetic; Surgery; General anesthesia; Female; Pharmacokinetics; Obstetrics; Cesarean section
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/72.1.122

In this study we have measured arterial concentrations of isoflurane obtained during Caesarean section in two groups of patients. Patients in group 1 received 1% isoflurane throughout operation, whilst those in group 2 received 2% isoflurane for the first 5 min, 1.5% for the next 5 min and 0.8% thereafter. We found that arterial isoflurane concentrations were significantly greater in group 2 than in group 1 (ANOVA, P < 0.05). Isoflurane concentrations greater than 30 μg ml−1 were achieved rapidly in most patients in both groups, but there was a large scatter of results. The isoflurane concentration at which awareness or recall may occur is not known, but an “overpressure” technique as described for patients in group 2 may result in fewer patients being at risk of awareness. (Br. J. Anaesth. 1994; 72: 122–124)