Summary: We have studied the effects of subconvulsive doses of lignocaine on circulatory function in five conscious, chronically instrumented sheep. In the absence of overt signs of central nervous system toxicity, 50-, 75- or 100-mg i.v. bolus doses of lignocaine induced reductions in myocardial contractility, as assessed by the maximum rate of increase in left ventricular pressure (L V dP/dtmax, of 17 (SD4)%, 25 (4)% and 33 (4)%, respectively. The durations of these reductions in myocardial contractility were 2-3.5 min. There were no significant changes in cardiac output, coronary artery blood flow, mean arterial pressure, heart rate or left ventricular systolic and diastolic pressures. It is concluded that the initial toxic effects of lignocaine are on the heart rather than the central nervous system, as is generally believed. This negative inotropic effect of lignocaine in vivo may be more deleterious to myocardial function when the heart is compromised by pre-existing disease, or the co-administration of other myocardial depressive drugs.
- Myocardial depression
- Subconvulsive dose
ASJC Scopus subject areas
- Anesthesiology and Pain Medicine