Isoflurane Esmolol

Unlike isoflurane, desflurane may stimulate the sympathetic nervous system at concentrations above 1 MAC. Sudden and unexpected increases in arterial blood pressure and heart rate have been reported in some patients, accompanied by increases in plasma catecholamine and vasopressin concentrations and increased plasma renin activity. These pressor effects may increase morbidity or mortality in susceptible patients. The mechanism of sympathetic activation is unclear but does not appear to be baroreceptor-mediated. Clonidine, esmolol, fentanyl and propofol partially block the response but lignocaine (lignocaine) is ineffective. 

The effects of alfentanil and esmolol on isoflurane requirements for anesthesia have been studied in a randomized trial in 100 patients (22). Alfentanil infusion to a targeted effect site concentration of 50 ng/ml, but not esmolol, reduced the minimum alveolar concentration of isoflurane required to suppress movement to surgical pain by 25%. The combination of esmolol and alfentanil caused a 74% reduction in isoflurane requirements. This study is interesting, because the beta-blocker esmolol had a profound effect on the isoflurane-sparing effects of alfentanil, while having little effect on its own. 

Johansen JW, Schneider G, Windsor AM, Sebel PS. Esmolol potentiates reduction of minimum alveolar isoflurane concentration by alfentanil. Anesth Analg 1998 87(3) 671-6. 

Several studies have similarly found that the use of esmolol reduced the required dose of isoflurane or propofol, or resulted in a deeper anaesthesia (as measured by BIS), but only in the presence of an opioid. " As there appears to be no pharmacokinetic interaction between esmolol and propofol it has been suggested that esmolol could be interacting with the opioid. ... 

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See also in sourсe #XX -- [ ]

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