As early as 1903 Braun demonstrated that the addition of epinephrine to local anaesthetic solutions greatly prolonged their duration of action, k Since then epinephrine has been used widely in clinical practice not only to prolong anaesthesia but also to provide optimal haemostasis and to minimize the systemic toxic effects of local anaesthetics. 2'3 Significant haemodynamie and metabolic effects have been documented following epinephrinelocal anaesthetic infiltration. 4'5Although epinephrine has been reported to delay the absorption of local anaesthetics, little information is available about the effect of local anaesthetics on epinephrine absorption. In a recent study Ueda et al. found that, in combination with lidocaine, the absorption of epinephrine is accelerated following cutaneous infiltration. A local vasodilatatory effect of lidocaine has been postulated as the mechanism. 6The objectives of this study were to investigate the effect of lidocaine and bupivacaine on the absorption of epinephrine following rectal mucosal infiltration: to study the systemic absorption of the local anaesthetics employed, and to assess the cardiovascular and metabolic effects of the absorbed epinephrine.
MethodsEmploying a randomised cross-over trial design, three groups of five greyhounds weighing 23-33 kg were allocated to receive 1.5p.g.kg -1 of epinephrine 1/ 200,000 in either 0.3 ml 'kg-1 normal saline, 0.5 per cent bupivacalne or 0.5 per cent lidocaine. Following induction of anaesthesia with thiopentone 20 mg. kg-t I.V., controlled ventilation to normocapnia was commenced. Anaesthesia was maintained with halothane 1.5 per cent in oxygen and the oesophageal temperature was mainmined between 37-38~ Continuous ECG, end-tidal CO2 and direct intra-arterial blood pressure were monitored throughout. Following tracheal intubation and cannulation of the femoral artery, a ten-minute period was allowed to elapse to permit any sympathoadrenal response to wane. Baseline arterial blood samples were then taken CAN J ANAESTH 1989 / 36:4/pp 397-401
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.