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A BIS‐guided study of sevoflurane requirements for adequate depth of anaesthesia in Caesarean section
Author(s) -
Chin K. J.,
Yeo S. W.
Publication year - 2004
Publication title -
anaesthesia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.839
H-Index - 117
eISSN - 1365-2044
pISSN - 0003-2409
DOI - 10.1111/j.1365-2044.2004.03944.x
Subject(s) - sevoflurane , medicine , caesarean section , bispectral index , anesthesia , receiver operating characteristic , elective caesarean section , pregnancy , propofol , biology , genetics
Summary Caesarean section carries a high risk of awareness, especially in the period prior to neonatal delivery. We investigated the concentration of sevoflurane required to maintain bispectral index (BIS) < 60 until delivery occurred. We enrolled 23 parturients into an up–down sequential allocation study. The median effective end‐tidal concentration (EC 50 ) of sevoflurane was defined as that which maintained BIS < 60 between skin incision and delivery in 50% of patients. This was calculated using Dixon and Massey's method. Receiver operating characteristic curve analysis was used to establish BIS response probability thresholds. The EC 50 for sevoflurane was 1.22% (1.08–1.33, 95% CI). The probability of maintaining BIS < 60 was < 55% at a concentration of < 1.1%; this increased to 80% at concentrations of 1.2–1.3%. We conclude that sevoflurane concentrations of at least 1.2–1.3% should be administered in uncomplicated Caesarean section, so as to minimise the risk of awareness and recall.