THE SYNDROME OF DEHYDRATION, COMA AND SEVERE HYPERGLYCEMIA WITHOUT KETOSIS IN PATIENTS CONVALESCING FROM BURNS

Hypernatremia in Hyperglycemia: Clinical Features and Relationship to Fractional Changes in Body Water and Monovalent Cations during Its Development

In hyperglycemia, the serum sodium concentration ([Na]S) receives influences from (a) the fluid exit from the intracellular compartment and thirst, which cause [Na]S decreases; (b) osmotic diuresis with sums of the urinary sodium plus potassium concentration lower than the baseline euglycemic [Na]S, which results in a [Na]S increase; and (c), in some cases, gains or losses of fluid, sodium, and potassium through the gastrointestinal tract, the respiratory tract, and the skin. Hyperglycemic patients with hypernatremia have large deficits of body water and usually hypovolemia and develop severe clinical manifestations and significant mortality. To assist with the correction of both the severe dehydration and the hypovolemia, we developed formulas computing the fractional losses of the body water and monovalent cations in hyperglycemia. The formulas estimate varying losses between patients with the same serum glucose concentration ([Glu]S) and [Na]S but with different sums of monovalent cation concentrations in the lost fluids. Among subjects with the same [Glu]S and [Na]S, those with higher monovalent cation concentrations in the fluids lost have higher fractional losses of body water. The sum of the monovalent cation concentrations in the lost fluids should be considered when computing the volume and composition of the fluid replacement for hyperglycemic syndromes.

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.

Practical aspects of intensive insulinization in the intensive care unit

PURPOSE OF REVIEW

Strategies used for intensive insulin therapy of critically ill patients and differences of approach according to medical condition are reviewed.

RECENT FINDINGS

Acceptance of proposed glycemic targets for critically ill patients has been tempered by uncertainties about benefit of strict glycemic control for specific target subpopulations, differences between treatment centers, optimal timing and duration of intervention, and safety. Present-day intravenous insulin infusion protocols may perform well only for restricted populations. Assessment of protocol performance requires knowledge of algorithm behavior on or near the narrow target range and, using the patient as unit of observation, examination of glycemic variability. Systems of the future will permit adjustment of algorithm parameters to meet individual- or population-specific targets and match carbohydrate exposure.

SUMMARY

Attainment and preservation of glycemic control among critically ill patients are best attempted with intravenous insulin infusion. Advances in the design of decision support and insulin delivery systems, and progress in the technology of continuous blood glucose monitoring, are likely to reduce the risk of hypoglycemia, without compromise of target range control, such that the patient outcomes enjoyed by experienced centers in the future will prove generalizable to others through the extension of new technologies.

The lateral hypothalamic area revisited: neuroanatomy, body weight regulation, neuroendocrinology and metabolism

This article reviews findings that have accumulated since the original description of the syndrome that follows destruction of the lateral hypothalamic area (LHA). These data comprise the areas of neuroanatomy, body weight regulation, neuroendocrinology, neurochemistry, and intermediary metabolism. Neurons in the LHA are the largest in the hypothalamus, and are topographically well organized. The LHA belongs to the parasympathetic area of the hypothalamus, and connects with all major parts of the brain and the major hypothalamic nuclei. Rats with LHA lesions regulate their body weight set point in a primary manner and not because of destruction of a "feeding center". The lower body weight is not due to finickiness. In the early stages of the syndrome, catabolism and running activity are enhanced, and so is the activity of the sympathetic nervous system (SNS) as shown by increased norepinephrine excretion that normalizes one mo later. The LHA plays a role in the feedback control of body weight regulation different from ventromedial (VMN) and dorsomedial (DMN). Tissue preparations from the LHA promote glucose utilization and insulin release. Although it does not belong to the classical hypothysiotropic area of the hypothalamus, the LHA does affect neuroendocrine secretions. No plasma data on growth hormone are available following electrolytic lesions LHA but electrical stimulation fails to elicit GH secretion. Nevertheless, antiserum raised against the 1-37 fragment of human GHRF stains numerous perikarya in the dorsolateral LHA. The plasma circadian corticosterone rhythm is disrupted in LHA lesioned rats, but this is unlikely due to destruction of intrinsic oscillators. Stimulation studies show a profound role of the LHA in glucose metabolism (glycolysis, glycogenesis, gluconeogenesis), this mechanism being cholinergic. Its role in lipolysis appears not to be critical. In general, stimulation of the VMN elicits opposite effects. Lesion studies in rats show altered in vitro glucose carbon incorporation into several tissue fractions both a few days, and one mo after lesion production. Several of these changes may be due to the reduced food intake, others appear to be due to a "true" lesion effect.

Hyperosmolar hyperglycemic nonketotic syndrome. Report of 22 cases and brief review

In a series of 22 patients with the hyperosmolar hyperglycemic nonketotic syndrome managed during a five-year period in a community hospital setting, 21 patients were known to be diabetic and only six patients were in coma. The overall mortality was 36.3 percent, and seven of the eight deaths were explained by associated nonmetabolic causes. In this study, hyperosmolarity was not related to coma or to final outcome of treatment. Patients were managed with relatively small amounts of fluid, and the type of fluid used did not influence the final outcome.

Hyperosmolar nonketotic coma in the elderly diabetic

The gravity of this syndrome of severe diabetic stupor without ketosis may not be recognized because patients are usually middle-aged or elderly with mild diabetes. A lack of urgency in treating these patients is probably the cause of the widely reported mortality of 40 to 70 per cent.

Secondary metabolic encephalopathy. Diagnosis and treatment

Secondary metabolic encephalopathy is a diffuse disorder of the brain caused by an extracerebral process. Underlying causes include oxygen deprivation, systemic metabolic disease, and drug intoxication. Symptoms and signs usually suggest a generalized disturbance of brain function: alterations in the level of consciousness; diffuse and, occasionally, focal motor abnormalities; and seizures. Electroencephalography in most instances gives evidence of generalized neuronal disturbance. Early diagnosis is important because encephalopathy secondary to an extracerebral process is potentially reversible. Treatment is directed toward reversal or control of the underlying process, supportive care, and prevention of complications such as infection, electrolyte imbalance, and cerebral edema.

Pathogenesis of nonketotic hyperosmolar diabetic coma

Two concepts are advanced to explain some fo the puzzling biochemical features found in nonketotic hyperosmolar diabetic coma. It is firstly suggested that an insulinised liver (reflecting residual beta-cell secretory activity) coexists with a diabetic periphery, thereby inactivating intrahepatic oxidation of incoming free fatty acids, which are directed largly along nonketogenic metabolic pathways such as triglyceride synthesis. This could account for the lack of hyperketonaemia. Secondly, it is hypothesised that within the liver enhanced neoglucogenesis occurs, due to the prevailing portal-vein into ratio of glucagon to insulin, and is mainly responsible for the development of massive hyperglycaemia.