Hyperglycemic diabetic emergencies fall into two broad categories: diabetic ketoacidosis and hyperosmolar non-ketotic coma. Both emergencies have a relatively high mortality: approximately 5 per cent for diabetic ketoacidosis and 50 per cent for hyperosmolar non-ketotic coma ( HiJJman 1991; Hammon.d,,§Dd..,WaiIi.S 1992;

Lebovitz 1995). The high mortality is probably related as much to the underlying chronic organ impairment and precipitating factors as to the acute physiological disturbance. For all these reasons, patients with diabetic emergencies are at high risk of further pathophysiological insults, such as hypoxia and ischemia, and they require rapid and competent resuscitation. It is recommended that these high-risk patients are managed in an intensive care environment until they are fully resuscitated and stable.

Patients with diabetic ketoacidosis have decreased or absent insulin levels, whereas patients with hyperosmolar non-ketotic coma have more of a peripheral resistance to insulin. Hyperglycemia, which leads to glycosuria and an osmotic diuresis, occurs in both types of patients. The osmotic diuresis can result in large fluid and electrolyte losses. Lipolysis, free fatty acid release, and ketone formation also occur in patients with diabetic ketoacidosis.

Precipitating factors in both conditions include infection, myocardial infarction, thromboembolic disorders, and poor patient compliance with medication. The principles of management for the two conditions are similar. Common aspects of management will be considered below. Initial assessment

Most current textbooks and reviews begin by recommending insulin replacement as first-line treatment for diabetic emergencies. Although this seems logical, it is not the highest priority. Neither the lack of insulin nor the high blood glucose are in themselves an immediate threat to the patient's life. It is the pathophysiological sequelae of the high blood glucose such as hypovolemia and hypoxia which demand immediate attention. Patients with diabetic emergencies require the same standardized approach as any other life-threatening emergency—airway, breathing, and circulation (,.BIalt0D..,§Dd..,K.r.aD,e 1992).

Control and protection of the airway is the first priority. Approximately 10 per cent of patients with diabetic ketoacidosis are initially unconscious, and the majority of patients with hyperosmolar non-ketotic coma are comatose. Control of the airway may simply require positioning or an oral airway. However, there should be a low threshold for intubating an unconscious patient. Patients with a Glasgow Coma Scale of 9 or less require intubation.

Attention to breathing is the next priority. Patients with diabetic ketoacidosis are normally hyperventilating as a result of the metabolic acidosis. The lung fields on chest radiography are typically overexpanded. Comatose patients are at risk of aspiration. Patients with hyperosmolar non-ketotic coma are usually older and more obese than those with diabetic ketoacidosis. This, combined with a decrease in the level of consciousness, can predispose to basal collapse and pneumonia. Oxygen requirements need to be assessed with pulse oximetry and arterial blood gases. For a conscious patient, continuous positive airway pressure via a mask may be beneficial for prevention and treatment of basal collapse. Occasionally, intubation and artificial ventilation are also necessary. Once the airway and breathing have been assessed and initial treatment undertaken, hypovolemia should be corrected.

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