British Journal of Anaesthesia, 1977, Vol. 49, No. 12 1179-1188
© 1977 The Board of Management and Trustees of the British Journal of Anaesthesia
research-article |
HAEMODYNAMIC RESPONSES TO ISOFLURANE ANAESTHESIA AND HYPOVOLAEMIA IN THE DOG, AND THEIR MODIFICATION BY PROPRANOLOL
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The Nuffield Department of Anaesthetics, University of Oxford, The Radcliffe Infirmary Oxford
Requests for reprints to C. P.-R.
In six dogs chronically implanted with flow and pressure transducers, equipotent inspired concentrations of halothane and isoflurane were determined as the minimum inspired concentration of each agent which would abolish an individual dog's response to paw clamping. In equipotent concentrations, isoflurane (1.2%, SD 0.2%) caused less myocardial depression than halothane (1.0%, SD 0.1%). Doseresponse studies were possible up to a mean inspired isoflurane concentration of 3.0%, both before and after propranolol 0.3 mg kg-1, i.v. After propranolol, sensitive indices of myocardial contractility were depressed at all concentrations of isoflurane, indicating a moderate degree of ß-receptor activation by isoflurane. The hacmodynamic response to hypovolaemia during isoflurane anaesthesia was not modified by propranolol.
*Present addresses:Department of Anaesthetics, St Vincent's Hospital,Darlinghurst, N.S.W. 2010, Australia.
Present addresses:Department of Anaesthesia, University of Bristol,Bristol Royal Infirmary, Bristol BS2 8HW.
Present addresses:Department of Anaesthesia, Flinders University,South Australia, Bedford Park, South Australia 5042.