Adverse haemodynamic effects of the rapid intravenous injection of hypotonic solutions in sheep

The rapid intravenous administration of 10 ml of sterile water or hypotonic saline to five conscious sheep induced substantial adverse haemodynamic effects lasting 10 to 20 seconds. They included reductions in cardiac output (to 44 per cent of the baseline value measured in the 30 seconds before the injection), arterial blood pressure (67 per cent of baseline), left ventricular systolic pressure (60 per cent of baseline), myocardial contractility (60 per cent of baseline), and left coronary arterial blood flow (39 per cent of baseline), and increases in heart rate to 137 per cent of the baseline. The intensities of these effects were related directly to the rates of injection and inversely to the osmolalities of the solutions injected. Intravascular haemolysis was associated with the effects. These data are of potential importance to anyone administering drugs intravenously to sheep.