Iatrogenic hyperosmolality in critically ill low-birth-weight infants.

Twenty-four desperately ill newborn infants of very low-birth-weight admitted to a referral unit were studied. Some had received sodium bicarbonate (8.4% solution) in 20% glucose as an intravenous bolus infusion before admission. After admission continuous intravenous infusion was started with 10% glucose (70-100 ml/kg/24 hr) to which 5-15 ml/kg/24 hr of 4.2% sodium bicarbonate solution was added (2.5-7.5 mEq/kg/24 hr). In a few infants at admission, and in all some time after the beginning of treatment, blood samples for determination of glucose, lactate, sodium, urea nitrogen, osmolality and acid base status were obtained. In some infants blood samples were also taken immediately before or after death. During the course of intravenous infusion therapy, a progressive increase in mena osmolality was observed, accompanied by a rise in blood glucose, sodium and urea levels. The highest mean plasma osmolality was observed immediately before or after death. Besides continuous intravenous infusion, in several infants repeated attempts were made to correct the recurring acidosis by bolus infusion. Hyperosmolality is a frequent consequence of vigorous infusion therapy aimed at correcting acidosis and covering fluid and caloric requirement of maintenance. A simultaneous elevation in plasma sodium and glucose is often produced on utilizing two hyperosmolar solutions (sodium bicarbonate and glucose). The progressive increase in blood urea content also contributes to hyperosmolality. The metabolic, cellular and compartmental effects of hyperosmolality as well as the possible injury to the brain are discussed.