Diabetic ketoacidosis and coma

Cerebral edema in diabetic ketoacidosis

OBJECTIVE

To review the causes of cerebral edema in diabetic ketoacidosis (CEDKA), including pathophysiology, risk factors, and proposed mechanisms, to review the diagnosis, treatment, and prognosis of CEDKA and the treatment of diabetic ketoacidosis as it pertains to prevention of cerebral edema.

DATA SOURCE

A MEDLINE search using OVID was done through 2006 using the search terms cerebral edema and diabetic ketoacidosis. RESULTS OF SEARCH: There were 191 citations identified, of which 150 were used. An additional 42 references listed in publications thus identified were also reviewed, and two book chapters were used.

STUDY SELECTION

The citations were reviewed by the author. All citations identified were used except 25 in foreign languages and 16 that were duplicates or had inappropriate titles and/or subject matter. Of the 194 references, there were 21 preclinical and 40 clinical studies, 35 reviews, 15 editorials, 43 case reports, 29 letters, three abstracts, six commentaries, and two book chapters.

DATA SYNTHESIS

The data are summarized in discussion.

CONCLUSIONS

The causes and mechanisms of CEDKA are unknown. CEDKA may be due as much to individual biological variance as to severity of underlying metabolic derangement of the child's state and/or treatment risk factors. Treatment recommendations for CEDKA and diabetic ketoacidosis are made taking into consideration possible mechanisms and risk factors but are intended as general guidelines only in view of the absence of conclusive evidence.

Treatment of diabetic ketoacidosis and non-ketotic hyperosmolar diabetic coma

Although mortality of diabetic ketoacidosis (KA) has decreased during the past 20 yr to 1-2%, hyperosmolar non-ketotic coma (HNC) is still lethal in 20-30% of cases due to severe underlying conditions or to complications. The most frequent causes of death are infections and thromboembolic disorders. The strategies of initial treatment of KA and HNC are similar; in KA, insulin, fluid and electrolyte replacement have first priority. In HNC, rehydration and electrolyte administration are of primary importance. It is now generally recognized that insulin therapy is best performed using low doses (4-8 units/h); after institution of insulin treatment and rehydration there are rapid changes of fluid and electrolytes from the extra- into the intravascular space. In this situation it is a major therapeutic challenge to avoid complications due to hypokalaemia, hypophosphataemia, hypomagnesaemia and hypovolaemia. These complications should be avoided by adequate replacement, and particularly by regular clinical and laboratory monitoring. When blood glucose concentrations decrease below 14 mmols/l, blood glucose concentrations should initially be maintained at this level because rapid lowering below this level may increase the risk of brain oedema. Too-vigorous fluid replacement with crystalline solutions also increases the risk that brain oedema or complications like the adult respiratory distress syndrome will develop. If hypovolaemia persists in spite of adequate crystalloid solutions, colloid-containing fluids such as albumin should be administered. It is not established whether replacements of phosphate and magnesium have clinical benefits. Nevertheless, it is probably justified to administer phosphate and magnesium when their serum concentrations are below the normal range, particularly if the clinical situation is critical. Mortality from diabetic coma in industrialized countries may only be decreased by prophylaxis, i.e. by education of all diabetic patients and physicians to detect metabolic decompensation early.

Bedside blood ketone body monitoring

The use of a reagent strip and reflectance meter for the bedside measurement of 3-hydroxybutyrate during the clinical management of diabetic ketoacidosis is described. Comparison of this method with a laboratory enzymatic assay shows good correlation (r = 0.97, p less than 0.05). Initial use in acute ketoacidosis suggests that knowledge of hourly changes in 3-hydroxybutyrate levels could be helpful in determining the optimum insulin dose.

Concepts of fluid therapy in diabetic ketoacidosis and hyperosmolar hyperglycemic nonketotic coma

Despite many advances in the overall treatment of type I diabetes mellitus during the last few years, no major advance has been made in decreasing the mortality rate of diabetic ketoacidosis or hyperosmolar hyperglycemic nonketotic coma. A major concern in both of these disease states is the development of cerebral edema during treatment. The guiding principles of therapy in both disease states are rehydration, electrolyte replacement, insulin therapy, and treatment of any underlying illnesses. If the patient is hypotensive, therapy begins with colloid or normal saline administration to support blood pressure. Fluid and electrolyte deficits should be calculated and replaced during 48 hours. Low-dose insulin therapy is employed for treatment of hyperglycemia. Neurologic function should be carefully monitored and mannitol administered if a change in neurologic function occurs.

Non-traumatic coma in Zambia

A series of 170 patients with non-traumatic coma seen over a 16-month period is reported. The Glasgow coma scale significantly correlated with outcome (P less than 0.001). The diagnosis was also important in determining outcome. Hospital mortality was lowest in patients with cerebral malaria (22.7%), eclamptic coma (36.4%), and organophosphorous poisoning (30.4%). A diagnostic approach to non-traumatic coma is outlined and the management of the different causes is discussed. Most hospitals in tropical Africa should be able to diagnose up to 90% of cases with non-traumatic coma and simple therapy is likely to be effective in the majority of cases.

Fluid resuscitation in diabetic emergencies--a reappraisal

The first objective in diabetic ketoacidosis is to restore the circulating volume and improve tissue perfusion. In any form of hypovolaemic shock the most efficient way of restoring circulating volume is to be use colloid solutions rather than crystalloids. At least three times the amount of crystalloid must be used to achieve the same effect. The historical reason for using isotonic saline in diabetic ketoacidosis is related not to its similarity to the fluid lost, but to its supposed efficiency in correcting the circulating volume. Excess crystalloid expands the interstitial space which results in pulmonary oedema, peripheral oedema and possibly cerebral oedema. Although currently difficult to define precisely in their more subtle forms, they all produce adverse pathophysiological effects. The fluid loss in diabetic ketoacidosis is equivalent to "half-normal" saline, a relatively hypotonic solution. As well as causing extensive oedema, resuscitation with isotonic saline can increase serum sodium and osmolarity while not providing free water to replace the intracellular losses.