What is a Hyperosmolar Coma?
Hyperosmolar coma is most often found in people over 50 with a mild or moderate diabetes mellitus, well compensated by a diet or sulfanyl-urea preparations. Hyperosmolar coma occurs 1:10 in relation to the ketoacidotic coma, and mortality during its development is 40-60%.
Causes of Hyperosmolar Coma
This pathological condition occurs during metabolic decompensation of diabetes mellitus and is characterized by extremely high blood glucose (55.5 mmol / L or more) in combination with hyperosmolarity (from 330 and up to 500 or more mosmol / L) and the absence of ketoacidosis.
Pathogenesis during hyperosmolar coma
The mechanism of this pathological condition is not fully understood. It is assumed that the blockade of glucose excretion by the kidneys is of great importance in the development of high glycemia (up to 160 mmol / L).
Hyperglycemia is combined with fluid loss resulting from osmotic stimulation of diuresis, inhibition of the production of antidiuretic hormone by the neurohypophysis and a decrease in water reabsorption in the distal tubules of the kidneys.
With rapid and significant loss of fluid, BCC decreases, blood thickens and osmolarity increases due to an increase in the concentration of not only glucose, but also other substances contained in the plasma (for example, potassium and sodium ions). Thickening and high osmolarity (more than 330 mosmol / L) lead to intracellular dehydration (including brain neurons), impaired microcirculation in the brain, decreased cerebrospinal fluid pressure, which are additional factors contributing to the development of coma and the appearance of specific neurological symptoms.
Symptoms of the Hyperosmolar Coma
Clinic of hyperosmolar coma. Provoking factors are similar to the causes causing the development of ketoacidotic coma. Coma develops gradually. A history of diabetes mellitus prior to the onset of coma was usually mild and was well compensated by the use of oral hypoglycemic drugs and diet.
A few days before the development of coma, patients note increasing thirst, polyuria, weakness. The condition is constantly deteriorating, dehydration develops. Disturbances of consciousness appear – drowsiness, lethargy, gradually turning into a coma.
Neurological and neuropsychic disorders are characteristic: hallucinations, hemiparesis, slurred speech, cramps, areflexia, increased muscle tone, sometimes there is a high temperature of central origin.
Diagnosis of Hyperosmolar coma
In the blood there is an extremely high level of glycemia and osmolarity, ketone bodies are not detected.
Hyperosmolar Coma Treatment
The principles of emergency care in this condition are similar to those in the treatment of ketoacidotic coma and consist in eliminating dehydration, hypovolemia and restoring normal plasma osmolarity, and proper infusion therapy with hyperosmolar coma becomes even more important than with ketoacidosis.
Infusion therapy for hyperosmolar coma. Within 1-2 first hours in / in a drop, 2-3 liters of a 0.45% sodium chloride solution (hypotonic solution) are rapidly injected, followed by an infusion of an isotonic solution and its administration is continued against the background of insulin therapy until the level plasma glucose will not decrease to 12-14 mmol / l. After that, to prevent the development of a hypoglycemic state, they switch to iv administration of a 5% glucose solution with the appointment of insulin for its utilization (4 IU of insulin per 1 g of glucose). The adequacy of the volume of infusion therapy is assessed according to generally accepted criteria. Quite often, for stopping dehydration in this group of patients, very large volumes of fluid in the amount of up to 15-20 l / 24 hours are required. Naturally, infusion therapy should include correction of electrolyte levels.
Given that with this pathology there is no ketoacidosis, and therefore there is no metabolic acidosis, the use of buffer solutions is not shown.
When treating this pathology, the doctor should not be confused by the initial extremely high values of the blood glucose level. It must always be remembered that hyperosmolar coma occurs, as a rule, in patients with mild or moderate severity of diabetes mellitus, therefore they respond very well to the administered insulin. Based on this, it is not recommended to use large doses of this drug, but to use the method of continuous iv infusion of small doses of insulin, and the initial working dose should not be increased more than 10 U / hour (0.1 U / kg).