Intravenous Infusion of Halothane Dissolved in Fat. Haemodynamic Effects in Dogs

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Abstract
Eight harrier dogs received an i.v. infusion of halothane dissolved 1:9 in a fat emulsion for i.v. nutrition (Intralipidr̀, Vitrum). The rate of infusion was adjusted to maintain end‐tidal halothane concentrations of 0.7% and 1.4%. At 1.4%, mean arterial pressure decreased to 76 ± 8 mmHg (10.1 ± 1.0 kPa) (mean ± s.e.mean) from a pre‐infusion value of 122 ± 6 mmHg (16.2 ± 0.8 kPa) (PP<0.01). Changes in systemic vascular resistance and pulmonary arterial pressure were small. The haemodynamic responses during halothane inhalation, to corresponding end‐tidal concentrations, were similar. Arterial and mixed venous halothane concentration increased in proportion to end‐tidal concentration. There were no changes in arterial Po2 during the halothane‐in‐fat infusion. Triglyceride concentrations in plasma increased 12‐fold. Haemodynamic recovery after the infusion was fast. We conclude that the halothane‐in‐fat infusion caused a dose‐dependent depression of myocardial contractility and arterial pressure, similar to that seen during inhalation, and that end‐tidal concentration could be used for control of the infusion rate.