124 Hyperkalaemia in The Extremely Low Birth Weight Preterm Infant

Top of pageAbstract Background: The purpose of the study was to investigate factors that affect potassium(K) homeostasis over the first 6 days of life in extremely low birth weight (ELBW) preterm infants. Methods: Clinical and laboratory data was collected retrospectively on infants >23 and < 27 weeks admitted to NICU from January '01 to December '02. Infants were excluded if they had a congenital abnormality or died at < 24 hours. Haemolysed samples were excluded. Correlation of variables was analysed using Mann Whitney, Fisher Exact, one way ANOVA and multiple linear regression. Results: 80 infants were eligible with a median birth weight and gestational age of 722g(IQR 220g) and 25.0 wks(IQR 1.8 wks). 48(60.0%) had at least 1 episode of hyperkalaemia(K 6.5mmmol/L). Lowest mean K levels(4.8mmol/L SD 1.1) occurred on D1 rising to a peak mean (5.9 mmol/L SD 1.3) on D2 of life. Absolute [K] did not correlate with survival. There was a significant increase in [K] levels on D2–D3 in infants who died vs survivors (0.6mmol/L v–1.0mmol/L p= 0.0087). 16 of 45 infants died in the hyperkalaemic group (35.5%).15 of 31died in the normokalaemic group (48.4%). This was not significant. There was no correlation between [K] and [Na] concentration;mean arterial pressure;urine output;gestation;sex or pH. There was a negative correlation between glucose levels and [K] on days 2, 6 (p- values 0.02, 0.007). Mean [K] were significantly higher in infants who were hypoglycaemic (glucose< 2.8). This was noted on D2 of life(6.8mmol/L vs 5.6mmol/L p= 0.003). The mean [K] were significantly lower in infants who had received 2 doses of antenatal steroids(ANS) (n = 41) vs those who received none (n= 21) on D1(5.(1.1) vs 4.6 (0.9) mmol/L p-value= 0.02) and D2(6.5 (1.5) vs 5.(1.1) p= 0.009). There was no significant difference in [K] noted with 1 dose ANS compared with infants who were given no ANS; this was a small group. Conclusion: Hyperkalaemia affects almost¾ of ELBW preterm infants. [K] tend to rise from D1 to peak on D2. A rise on D3 is associated with a poorer chance of survival. The negative correlation between glucose and [K] may be due to lower substrate source of energy and a decrease in NA-K ATP-ase activity. ANS appear to have a protective effect on [K] levels in the first 48 hours of life in pregnancies of < 27 weeks possibly due to steroid induced maturation of Na-K ATP-ase2. 2.Omar S et al Effect of prenatal steroids on potassium balance in extremely low birth weight neonates.Pediatrics 2000;106(3):561–7