Unexpected death during treatment of uncomplicated diabetic ketoacidosis

Brain injury in children with diabetic ketoacidosis: Review of the literature and a proposed pathophysiologic pathway for the development of cerebral edema

Cerebral edema (CE) is a potentially devastating complication of diabetic ketoacidosis (DKA) that almost exclusively occurs in children. Since its first description in 1936, numerous risk factors have been identified; however, there continues to be uncertainty concerning the mechanisms that lead to its development. Currently, the most widely accepted hypothesis posits that CE occurs as a result of ischemia-reperfusion injury, with inflammation and impaired cerebrovascular autoregulation contributing to its pathogenesis. The role of specific aspects of DKA treatment in the development of CE continues to be controversial. This review critically examines the literature on the pathophysiology of CE and attempts to categorize the findings by types of brain injury that contribute to its development: cytotoxic, vasogenic, and osmotic. Utilizing this scheme, we propose a multifactorial pathway for the development of CE in patients with DKA.

The Corrected Serum Sodium Concentration in Hyperglycemic Crises: Computation and Clinical Applications

In hyperglycemia, hypertonicity results from solute (glucose) gain and loss of water in excess of sodium plus potassium through osmotic diuresis. Patients with stage 5 chronic kidney disease (CKD) and hyperglycemia have minimal or no osmotic diuresis; patients with preserved renal function and diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS) have often large osmotic diuresis. Hypertonicity from glucose gain is reversed with normalization of serum glucose ([Glu]); hypertonicity due to osmotic diuresis requires infusion of hypotonic solutions. Prediction of the serum sodium after [Glu] normalization (the corrected [Na]) estimates the part of hypertonicity caused by osmotic diuresis. Theoretical methods calculating the corrected [Na] and clinical reports allowing its calculation were reviewed. Corrected [Na] was computed separately in reports of DKA, HHS and hyperglycemia in CKD stage 5. The theoretical prediction of [Na] increase by 1.6 mmol/L per 5.6 mmol/L decrease in [Glu] in most clinical settings, except in extreme hyperglycemia or profound hypervolemia, was supported by studies of hyperglycemia in CKD stage 5 treated only with insulin. Mean corrected [Na] was 139.0 mmol/L in 772 hyperglycemic episodes in CKD stage 5 patients. In patients with preserved renal function, mean corrected [Na] was within the eunatremic range (141.1 mmol/L) in 7,812 DKA cases, and in the range of severe hypernatremia (160.8 mmol/L) in 755 cases of HHS. However, in DKA corrected [Na] was in the hypernatremic range in several reports and rose during treatment with adverse neurological consequences in other reports. The corrected [Na], computed as [Na] increase by 1.6 mmol/L per 5.6 mmol/L decrease in [Glu], provides a reasonable estimate of the degree of hypertonicity due to losses of hypotonic fluids through osmotic diuresis at presentation of DKH or HHS and should guide the tonicity of replacement solutions. However, the corrected [Na] may change during treatment because of ongoing fluid losses and should be monitored during treatment.

Respiratory failure in diabetic ketoacidosis

Respiratory failure complicating the course of diabetic ketoacidosis (DKA) is a source of increased morbidity and mortality. Detection of respiratory failure in DKA requires focused clinical monitoring, careful interpretation of arterial blood gases, and investigation for conditions that can affect adversely the respiration. Conditions that compromise respiratory function caused by DKA can be detected at presentation but are usually more prevalent during treatment. These conditions include deficits of potassium, magnesium and phosphate and hydrostatic or non-hydrostatic pulmonary edema. Conditions not caused by DKA that can worsen respiratory function under the added stress of DKA include infections of the respiratory system, pre-existing respiratory or neuromuscular disease and miscellaneous other conditions. Prompt recognition and management of the conditions that can lead to respiratory failure in DKA may prevent respiratory failure and improve mortality from DKA.

Cerebral edema in children with diabetic ketoacidosis: vasogenic rather than cellular?

Cerebral edema (CE) is accumulation of water in the intracellular or extracellular spaces of the brain. Vasogenic edema occurs when there is breakdown of the tight endothelial junctions of the blood-brain barrier (BBB), leading to extravasation of intravascular protein and fluid into the interstitial space of the brain. In cellular edema the BBB remains intact and there is swelling of astrocytes with corresponding reduction in extracellular space. In this review we bring together clinical evidence from neuropathology and cerebral magnetic resonance (MR) studies in pediatric patients presenting in diabetic ketoacidosis (DKA), and use applied physiology to understand whether CE complicating DKA is vasogenic, rather than cellular in origin. Because the first-line of defense against CE is the interface between the intravascular compartment and the extracellular space in the brain much of the focus in this review is the BBB. The principal pathologic finding in fatal cases is perivascular with BBB disruption and albumin extravasation, suggesting increased vascular permeability. DKA induces an inflammatory response and the mechanism of BBB transcellular permeability may be an immunologic cascade that disrupts tight junctions. The principal MR finding in subclinical cases of CE is vasogenic rather than cellular edema. We propose that the following physiology be considered when treating cases: bolus dose of intravenous mannitol may result in fall in serum sodium concentration, and therefore clinical worsening. Failure to respond to mannitol should prompt the use of 3% hypertonic saline (HS). Bolus dose of intravenous 3% HS is expected to effect vasogenic edema provided that the reflection coefficient is close to 1. Failure to respond to 3% HS should prompt the use of mannitol.

Brain edema in diseases of different etiology

Cerebral edema is a potentially life-threatening complication shared by diseases of different etiology, such as diabetic ketoacidosis, acute liver failure, high altitude exposure, dialysis disequilibrium syndrome, and salicylate intoxication. Pulmonary edema is also habitually present in these disorders, indicating that the microcirculatory disturbance causing edema is not confined to the brain. Both cerebral and pulmonary subclinical edema may be detected before it becomes clinically evident. Available evidence suggests that tissue hypoxia or intracellular acidosis is a commonality occurring in all of these disorders. Tissue ischemia induces physiological compensatory mechanisms to ensure cell oxygenation and carbon dioxide removal from tissues, including hyperventilation, elevation of red blood cell 2,3-bisphosphoglycerate content, and capillary vasodilatation. Clinical, laboratory, and necropsy findings in these diseases confirm the occurrence of low plasma carbon dioxide partial pressure, increased erythrocyte 2,3-bisphosphoglycerate concentration, and capillary vasodilatation with increased vascular permeability in all of them. Baseline tissue hypoxia or intracellular acidosis induced by the disease may further deteriorate when tissue oxygen requirement is no longer matched to oxygen delivery resulting in massive capillary vasodilatation with increased vascular permeability and plasma fluid leakage into the interstitial compartment leading to edema affecting the brain, lung, and other organs. Causative factors involved in the progression from physiological adaptation to devastating clinical edema are not well known and may include uncontrolled disease, malfunctioning adaptive responses, or unknown factors. The role of carbon monoxide and local nitric oxide production influencing tissue oxygenation is unclear.

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.

Minimizing the risk of brain herniation during treatment of diabetic ketoacidemia: a retrospective and prospective study

We studied retrospectively, 219 episodes of diabetic ketoacidemia in 119 patients aged 13 months to 30 years, to determine the trend of the concentration of sodium in serum as glucose declined during treatment of uncomplicated episodes and of episodes with complications attributable to brain swelling. Of 20 complication, 13 were minor (headache only) and 7 major (death or near death). The concentration of sodium in serum failed to rise as that of glucose declined in 82 (54%) of 164 uncomplicated episodes and in 18 (95%) of 20 complicated episodes (p less than 0.01). Hence complications were more likely to occur among patients with a failure of the concentration of sodium to rise as glucose declined. Fifty-eight episodes of diabetic ketoacidemia in 40 patients aged 1 1/2 to 20 years were then studied prospectively on a 48-hour treatment plan to provide the volume of deficit evenly, with half the deficit of sodium in the first 42 hours. Sodium concentration in serum rose in 55 (95%) of 58 episodes as that of glucose declined. No patient had a major complication. We conclude that failure of the sodium concentration measured in serum to rise as glucose concentration declines is a marker for excessive administration of free water. An expanded repair period, with repair fluid containing an average of 125 mmol/L Na+ early in therapy, will usually protect against a downward trend in the concentration of sodium in serum and therefore against a rapid decline in effective serum osmolality. This regimen may be protective against near-death episodes and brain herniation during treatment.

Factors associated with brain herniation in the treatment of diabetic ketoacidosis

To determine factors contributing to life-threatening brain herniation in patients treated for severe diabetic ketoacidosis, we analyzed history, laboratory data, rate and composition of fluid and insulin administration, and time to onset of brain herniation in nine new cases and 33 prior reports. The overall rate of fluid administration was inversely correlated with the time of onset of herniation (r = -0.32, p = 0.04). Only 4 of 40 cases occurred at fluid intakes less than or equal to 4.0 L/m2/day. During treatment, "calculated" serum sodium concentrations fell significantly and were less than 130 mEq/L in 33% of cases at the time of herniation. These data indicate that excessive secretion of vasopressin may exacerbate the brain edema, and that limitation of the rate of fluid administration may be prudent.

Possible mechanism for cerebral oedema in diabetic ketoacidosis

This hypothesis, presented to explain the cerebral oedema that sometimes occurs during treatment of diabetic ketoacidosis (DKA), is based on activation of the Na+/H+ exchanger, a ubiquitous plasma-membrane transport system that functions in the regulation of cytoplasmic pH. Experimental acidification of the cytoplasm with weak organic acids activates the exchanger and, in the presence of extracellular Na+, leads to cell swelling. This swelling is osmotic, secondary to a net gain in Na+ and the anion of the weak organic acid. In DKA, cytoplasmic acidification results from high levels of circulating weak organic acids (ketoacids and free fatty acids) and activation of Na+/H+ exchange would similarly be expected. Conditions during conventional treatment of DKA should favour even greater activation of the exchanger and additional cell swelling would be predicted. The hypothesis is consistent with the clinical observation that clinically apparent cerebral oedema occurs with improvement in the patient's acid-base status rather than at the peak of the ketoacidosis.

Diabetic ketoacidosis. Biochemistry, physiology, treatment, and prevention

Diabetic ketoacidosis (DKA) is the most common cause of death of juvenile-onset diabetics, and as such represents an important issue for pediatricians. In this article, the author reviews the endocrinology of insulin and the glucose counter-regulatory hormones, which are the basis for the development of DKA. The effects of hyperglycemia and acidosis upon organ physiology are detailed, and this serves as the foundation for subsequent discussion of the management of the patient with DKA. Finally, the author summarizes current strategies for prevention of DKA in patients with diabetes.

Advantage in management of diabetic coma by intensive care

A brief review of some therapy results in 763 episodes of diabetic coma from 1960 to 1973 reveals a significant decrease in lethality after institution of an intensive care unit. Present aspects of management are: intensification of shock therapy, potassium substitution and treatment of cerebral edema. The possibly dangerous role of hypotonic solutions is discussed. The lowering of the as yet high lethality of diabetic coma is an urgent necessity.

Acute cerebral dysfunction in diabetic ketoacidosis: survivial followed by panhypopituitarism

We report a unique case of a 15-yr-old diabetic patient who survived ketoacidosis complicated by acute severe encephalopathy, hypopituitarism, and optic atropy. We reviewed our 25-yr experience with fatal diabetic ketoacidosis; three additional cases resembled the "cerebral edema" syndrome. We observed that (1) cerebral edema is not often documented in this syndrome, (2) the cause of the acute neuronal disturbance in these patients may be hypoxic, with cerebral edema a secondary development, and (3) development of encephalopathy was probably unrelated to overvigorour correction of acidosis and hyperglycemia in our cases.

Mortality in juvenile diabetes mellitus over 25 years

Deaths over the past 25 years associated with diabetes mellitus under the age of 15 years are reviewed. Information is derived from the Registrar General's figures for England and Wales and from the records of a large paediatric diabetic unit.

Course and prognosis of 86 episodes of diabetic coma. A five year experience with a uniform schedule of treatment

The admission data and the course of 58 episodes of severe diabetic ketoacidotic coma and of 28 episodes of non-ketotic coma are compared. The non-ketotic patients were older; initial blood glucose, osmolarity, blood urea and serum sodium concentration were higher than in the ketotic patients. Treatment in the first 24 hrs consisted of similar amounts of insulin in both coma forms, the presence of acidaemia did not increase the insulin needs. Acidaemia was corrected only when pH was below 7.20. The disadvantages of alkali therapy are emphasized. A comparison of the age groups of survivors and those patients who died within 72 hrs showed an increase in mortality with age. However, the mortality rates from ketotic and non-ketotic coma were similar in the age groups above 50 years. On admission, blood glucose, osmolarity and blood urea were higher in the fatal cases. Blood urea was the most important indicator of a fatal outcome. The response of blood glucose to insulin was impaired in the subsequently fatal cases. Insulin was given in "moderate" doses by constant infusion. The use of "small" doses is discussed. Early mortality was 14% in the ketotic and 29% in the non-ketotic cases. The most frequent causes of death were circulatory failure of undetermined origin, infections and thromboembolic complications.

Course and prognosis of 86 episodes of diabetic coma. A five year experience with a uniform schedule of treatment

The admission data and the course of 58 episodes of severe diabetic ketoacidotic coma and of 28 episodes of non-ketotic coma are compared. The non-ketotic patients were older; initial blood glucose, osmolarity, blood urea and serum sodium concentration were higher than in the ketotic patients. Treatment in the first 24 hrs consisted of similar amounts of insulin in both coma forms, the presence of acidaemia did not increase the insulin needs. Acidaemia was corrected only when pH was below 7.20. The disadvantages of alkali therapy are emphasized. A comparison of the age groups of survivors and those patients who died within 72 hrs showed an increase in mortality with age. However, the mortality rates from ketotic and non-ketotic coma were similar in the age groups above 50 years. On admission, blood glucose, osmolarity and blood urea were higher in the fatal cases. Blood urea was the most important indicator of a fatal outcome. The response of blood glucose to insulin was impaired in the subsequently fatal cases. Insulin was given in "moderate" doses by constant infusion. The use of "small" doses is discussed. Early mortality was 14% in the ketotic and 29% in the non-ketotic cases. The most frequent causes of death were circulatory failure of undetermined origin, infections and thromboembolic complications.

Studies on mechanisms of cerebral edema in diabetic comas. Effects of hyperglycemia and rapid lowering of plasma glucose in normal rabbits

To investigate the pathophysiology of cerebral edema occurring during treatment of diabetic coma, the effects of hyperglycemia and rapid lowering of plasma glucose were evaluated in normal rabbits. During 2 h of hyperglycemia (plasma glucose=61 mM), both brain (cerebral cortex) and muscle initially lost about 10% of water content. After 4 h of hyperglycemia, skeletal muscle water content remained low but that of brain was normal. Brain osmolality (Osm) (343 mosmol/kg H(2)O) was similar to that of cerebrospinal fluid (CSF) (340 mosmol/kg), but increases in the concentration of Na+, K+, Cl-, glucose, sorbitol, lactate, urea, myoinositol, and amino acids accounted for only about half of this increase. The unidentified solute was designated "idiogenic osmoles". When plasma glucose was rapidly lowered to normal with insulin, there was gross brain edema, increases in brain content of water, Na+, K+, Cl- and idiogenic osmoles, and a significant osmotic gradient from brain (326 mosmol/kg H(2)O) to plasma (287 mosmol/kg). By similarly lowering plasma glucose with peritoneal dialysis, increases in brain Na+, K+, Cl-, and water were significantly less, idiogenic osmoles were not present, and brain and plasma Osm were not different. It is concluded that during sustained hyperglycemia, the cerebral cortex adapts to extracellular hyperosmolality primarily by accumulation of idiogenic osmoles rather than loss of water or gain in solute. When plasma glucose is rapidly lowered with insulin, an osmotic gradient develops from brain to plasma. Despite the brain to plasma osmotic gradient, there is no net movement of water into brain until plasma glucose has fallen to at least 14 mM, at which time cerebral edema occurs.

Reversible cerebral oedema complicating diabetic ketoacidosis

A young man with diabetic ketoacidosis developed the clinical features of cerebral oedema. This resolved without specific treatment. The mortality from ketoacidosis might be reduced if the syndrome was suspected and treated earlier.