Background: Hyperkalemia is seen quite often in very low-birthweight (VLBW) infants and concentrations sometimes become high enough to cause cardiac arrhythmia. The purpose of the present study was to identify factors that increase serum concentrations of potassium in VLBW infants.
Methods: Retrospective comparative analysis was performed on 140 VLBW infants who had been admitted to the Toho University Perinatal Center between January 1993 and December 1999 and needed mechanical ventilation for respiratory distress. Serum concentrations of potassium at 24 and 48 h of age were compared in two groups of infants, those whose mothers did and did not receive antenatal steroid treatment. Risk factors for severe hyperkalemia were analyzed by multiple linear regression models and Pearson's partial correlation analysis.
Results: Antenatal steroid treatment reduced serum potassium concentrations significantly at 24 and 48 h, as well as the incidence of cardiac arrhythmia and necessity for glucose insulin treatment for severe hyperkalemia. Multiple linear regression showed the serum potassium concentration at 24 h of age was associated with antenatal steroid hormone treatment, 24 h fluid intake volume, serum sodium concentrations at 24 h, gestational weeks and sampling site. Serum concentration of potassium at 48 h of age was associated with blood urea nitrogen, gestational week, serum sodium concentration at 48 h of age and fluid intake between 24 and 48 h of age. Urine output volume and serum creatinine concentrations were not correlated with potassium concentrations at either age.
Conclusion: Antenatal steroid hormone treatment can reduce early hyperkalemia in VLBW infants and also the incidence of cardiac arrhythmia and the use of glucose insulin treatment.