Inhalational Agents General Comments Gaseous anaesthetics are mainly used for maintenance anesthesia after induction with an intra-venous agents. DRUGS (1) Ketamine Hydrochloride Indications/Comments Colourless liquid, light sensitive. Used as an intravenous or intramuscular anaesthesia. Used as induction agent in patients with low cardiac output states not due to primary myocardial failure. Sole agent in patients in whom the upper airway may be relatively inaccessible i.e. severe burns or trauma. In very low doses as a highly potent supplement during general anaesthesia using other agents. Cautions/Side Effects Main side effect due to produc-tion of hallucinations as part of emergence phenomena. This may be reduced by the use of a powerful sedative e.g. diazepam. Momentarily rise in blood pressure problems in hypertensive patients. Use of drug is contraindicated (relative only) in patients with psychiatric history and patients with uncontrolled hypertension. (2) Penthrane (Methoxyflurane) Indications/Comments Colourless liquid with characteristic odour. General anaesthetic used as inhalational agent. Powerful analgesic useful in sub-anaesthetic doses for pain relief especially in obstetrics. Maintains cardio-vascular stability during general anaesthesia. Good muscle relaxant during general anaesthesia. Multiple anaesthetics using penthrane in periods of greater than one month intervals may be associated with the development of fever and jaundice. High dosage may produce high output renal failure - causing decline in its use.
