Anesth Analg 2007;104:228-229
© 2007 International Anesthesia Research Society
doi: 10.1213/01.ane.0000249840.62985.c0
LETTER TO THE EDITOR
Editor-in-Chief Steven L. Shafer
Influence of Cisatracurium on Entropy Values During Propofol–Remifentanil Anesthesia
Pierre-Yves Lequeux, MD,
Gilbert Bejjani, MD, and
Remi Flament, MD
Department of Anaesthesia, CHU-Tivoli, La Louviere, Belgium, pilequeu{at}ulb.ac.be (Lequeux)
Department of Anaesthesia, Erasmus Hospital, Brussels, Belgium (Bejjani)
Department of Anaesthesia, CHU-Tivoli, La Louviere, Belgium (Flament)
To the Editor:
The Datex-Omeda Entropy monitor (GE Healthcare, Chalfont St. Giles, UK) assesses depth of anesthesia with three parameters derived from the electroencephalogram: state entropy (SE), response entropy (RE) and burst suppression ratio (BSR). RE but not SE has been shown to be falsely elevated because of electromyographic (EMG) activity (1,2) while BSR has not been shown to be influenced by EMG.
A 76-yr-old male patient was anesthetized with propofol and remifentanil administered using target-controlled infusions. The patient received 2 mg/kg of cisatracurium on induction of anesthesia. One hour after induction of anesthesia, both RE and SE increased with respective peak values of 96 and 81. We increased the propofol and remifentanil target concentrations to values that caused hypotension, and treated him with ephedrine boluses, but this treatment failed to alter the RE and SE. The train-of-four response elicited four twitches, indicating inadequate neuromuscular blockade. We treated the patient with 4 mg of cisatracurium, causing both RE and SE to abruptly decrease to 20 and 18 respectively, and BSR increased to 33 (Fig. 1).
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Figure 1. Time course of the entropy parameters during anesthesia. The bolus of 4 mg/kg cisatracurium (*) revealed the influence of electromyographic activity on the entropy parameters. RE: response entropy, SE: state entropy, BSR: burst suppression ratio, Ce: effect–site concentration (ng/mL for remifentanil and µg/mL for propofol). Propofol and remifentanil were administered with a target-control infusion targeting the effect-site.
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EMG artifact increased the RE and SE values, while depressing the BSR. This differs from prior reports suggesting that only RE is sensitive to EMG interference (1,2).
REFERENCES
- Baughman VL, Hofman WE, Koenig HM, et al. Recovery from paralysis with succinylcholine increased response entropy and EMG but not state entropy. J Clin Monit Comput 2005;19:201–5.[Medline]
- Liu N, Chazot T, Huybrechts I, et al. The influence of a muscle relaxant bolus on bispectral and datex-ohmeda entropy values during propofol-remifentanil induced loss of consciousness. Anesth Analg 2005;101:1713–8.[Abstract/Free Full Text]
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