Biochemical changes in burned patients.

OF the problems associated with anaesthesia and surgical treatment in burned patients, some are the result of secondary biochemical changes or indiscriminate attempts to reverse such changes (Hutchins, McLaughlin & Hayes, 1961; Stoner, 1969, 1970). For example, one of the most constant, if least striking, early features of the metabolic response to injury-including burn injury and surgical traumais a temporary fall in plasma potassium levels. This change may cause cardiac problems for the very elderly, those with pre-existing cardiac disease, and those who are total body potassium-depleted. It is certainly very dangerous for any patientwho has been treated with digoxin because it potentiates the actions of this drug, and may, therefore, promote severe arrhythmias such as complete heart block. Trouble can be avoided by very cautious use of digoxin and the addition of some potassium to any fluids given during and immediatelyafter operation(Fig. 1). Hypoglycaemia is also one of the biochemical changes which can cause problems more frequently than is generally realized, in severely burned patients, and those with pre-existing liver function disturbances (Fig. 2). Severely burned patients are likely to be glycogen-depleted within about 8 hr after injury, their energy requirements are extremely high, they rapidly develop severe calorie-protein malnutrition, and frequently they develop liver function abnormalities. Such patients are poorly equipped to compensate for even a short period of fasting, and may become severely hypoglycaemic during or after operations. Prophylactic infusions of carbohydrate can prevent this complication, and the fact that such patients are pseudo-diabetic is not a contra-indication to such treatment, it is an indication for insulin therapy if hyperglycaemia demonstrates that they are not utilizing the carbohydrate (Fig. 3a and b). E 4 -X E V 3 o x E 2