Influence of the baricity of a local anaesthetic agent on sedation with propofol during spinal anaesthesia

• Published in: British journal of anaesthesia : BJA Vol. 98; no. 4; pp. 515 - 518
• Main Authors: Yang, M.K., Kim, J.A., Ahn, H.J., Choi, D.H.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.04.2007; Oxford University Press; Oxford Publishing Limited (England)
• Subjects: Adolescent; Adult; anaesthetic techniques; anaesthetic techniques, subarachnoid; anaesthetics i.v; anaesthetics i.v., propofol; anaesthetics local; anaesthetics local, tetracaine; Anesthesia; Anesthesia, Spinal - methods; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Anesthetics, Local - administration & dosage; Anesthetics, Local - chemistry; Biological and medical sciences; Conscious Sedation - methods; Drug Administration Schedule; Electroencephalography - drug effects; Humans; Hypnotics and Sedatives - administration & dosage; Medical sciences; Middle Aged; propofol; Propofol - administration & dosage; sedation; Specific Gravity; subarachnoid; tetracaine; Tetracaine - administration & dosage; Tetracaine - chemistry; Varicose Veins - surgery; anaesthetics i.v., propofol; anaesthetic techniques, subarachnoid; anaesthetics local, tetracaine; sedation; Local anesthetic; Ester; General anesthetic; tetracaine; sedation; subarachnoid; anaesthetics i.v; Subarachnoid; Anesthesia; Propofol; Sedation; anaesthetic techniques; propofol; anaesthetics local; Tetracaine
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/aem038

This study examined the effect of different levels of spinal anaesthesia, induced by solutions of different baricity but containing the same amount of local anaesthetic agent, on the requirement for sedation with propofol. Thirty-six patients undergoing varicose vein surgery under spinal anaesthesia were randomly allocated to receive tetracaine 15 mg in 3 ml of either glucose 5% (hyperbaric) or CSF (isobaric). I.V. propofol was started 5 min after the intrathecal injection and was titrated to maintain a bispectral index (BIS) score of 65–75. The propofol requirements to maintain this range in the two groups were compared every 5 min. The propofol requirement was always lower in the hyperbaric group, with the differences becoming statistically significant 20 min after the intrathecal injection. Total consumption of propofol over the 55 min of the study was also less in the hyperbaric group. The known difference in level of spinal anaesthetic block induced by solutions of different baricity, but the same dose of local anaesthetic, was associated with different requirements for propofol sedation as determined by BIS assessment.