Halosin

A number of anaesthetic vaporisers specially designed for use with Halothane are available. Open, semi-open, semi-closed and closed circuit systems have all been used with good results.

For induction of anaesthesia:

• Adult: A concentration of 2-4% Halothane in Oxygen or Nitrous Oxide may be used.
• Children: A concentration of 1.5-2% Halothane in Oxygen or Nitrous Oxide is used.

For maintenance of anaesthesia:

• Adults and children: A concentration of 0.5-2% is usually required for maintenance of anaesthesia. The lower concentration is usually most suitable for elderly patients.

Post-op nausea, vomiting, and shivering; resp depression, hypotension, skeletal muscle relaxation, bradycardia.

Halothane is a volatile anaesthetic which is suitable for the induction and maintenance of anaesthesia for all types of surgery and in patients of all ages.

When inhaled, Halothane is absorbed through the alveoli into the bloodstream. In the bloodstream, Halothane circulates through the body to the principal site of action, the brain. Here Halothane causes a progressive depression of the central nervous system, beginning with the higher centers (cerebral cortex) and spreading to the vital centers in the medulla. This depression is reversible. However, its mode of action, like all anaesthetic agents, is unknown.

Halothane has a relatively low solubility in blood and therefore alveoli/blood concentrations equilibrate rapidly. The triexponential decline in Halothane blood concentrations following the end of administration is thought to represent distribution into three compartments; the vessel rich group (brain/heart/liver), the musculature and adipose tissue. Approximately 80% of the inhaled Halothane is eliminated unchanged by the lungs. The remaining 20% is metabolized in the liver by oxidative and under hypoxic conditions, reductive pathways. The main metabolites are trifluoroacetic acid, bromide and chloride salts (via the oxidative pathway) and fluoride salts (via the reductive pathway). The concentrations of metabolites peak 24 hours post-operatively and are eliminated by renal excretion during the following week.

Caution should be exercised during administration of adrenaline to patients anaesthetised with Halothane as dysrhythmias may be precipitated. For this reason the dose of adrenaline should be restricted and beta-receptor antagonists administered if necessary. Ensure adequate room ventilation when Halothane is being used. Keep the concentration of Halothane in air as low as possible.

Effect on ability to drive or operate machinery: Patients should be advised that performance at skilled tasks, such as driving and operating machinery, may be impaired for some time after general anaesthesia.

Accidental ingestion: Cases of ingestion must be treated symptomatically.

General (Inhalation) anesthetics