The American Pediatric Society and The Society for Pediatric Research 1999 Abstract

Pediatric Research (1999) 45, 337A–337A; doi:10.1203/00006450-199904020-02003

Mild Hypothermia (HT) after Global Hypoxic Ischemic (HI) Insult Reduces the Creatinine (Cr) Rise and Increases Sodium Loss

Saulius Satas1, Helen Porter1, Peter Urdal1, Peter A Steen1 and Marianne Thoresen1

1Departments of Pediatrics and Experimental Medical Research, Ulleval University Hospital, Oslo, Norway, Department of Pediatric Pathology, University of Bristol, Bristol, UK, Department of Clinical Chemistry and, Department of Anesthesiology, Ulleval University Hospital, Oslo, Norway, Division of Child Health, University of Bristol, Bristol, UK

Abstract 1987

Background: Mild hypothermia as an neuroprotective is currently being investigated after head trauma and birth asphyxia. Deep and moderate body temperature of 20°C and 28°C has been shown to inpair kidney function implying changes in fluid management and drugs administration. The effect of mild HT and HI in newborns or adults has not been studied. Kidney function as well as the morphology are similar in newborn pigs and humans, hence our global model of HI is suitable to study the effect of neuroprotective interventions (like hypothermia) on the kidney function.

Aim: To evaluate whether 24 h mild HT has any effect on renal function and kidney pathology in newborn piglets subjected to a severe global HI insult.

Methods: Newborn pigs, < 48 h old, were anesthetized, ventilated and subjected to a 45 min global HI insult by reducing F1O2 ( 6%) until EEG was low amplitude ≤ 7 µV. Arterial pH at the end of the insult was 6.9 ± 0.10. On reoxygenation 18 were maintained NT (39°C) for 72 h and 18 were cooled to 35.0°C for the first 24 h followed by 48 h NT. Iv. fluids were given for 24 h followed by oral feeds as tolerated and electrolytes were supplemented if necessary. Creatinine (Cr) and sodium (Na) serum levels were measured at + 6, 12, 24, 30, 48 and 72 h after HI. The kidneys were immersion fixed and examined using light microscopy for degree of damage on a scale 0-3.

Results: Creatinine serum concentration started to rise by 12 h in the NT group and peaked at 48 h after HI insult. In the HT group Cr was lower than baseline after 2 h and was significantly lower at 24 h than in NT group, 59 ± 21 vs. 79 ± 28 µmol/L. The serum Na concentration was consistently lower than baseline in the HT group at 6, 12, 24 and 30 h after HI while the total amount of Na and fluids given was not different between the groups. There was no difference in weight gain at any time between the groups. Kidney damage occurred in 10/18 HT and 9/18 NT pigs.

Conclusion: 24 h of mild hypothermia is associated with increased Na loss and may require supplementation. We found no difference in kidney pathology in newborn pigs who were subjected to 24 h mild HT or NT after a severe global HI insult.