THE EFFECT OF SEVERE HEAD-INJURY ON WHOLE-BODY ENERGY-EXPENDITURE ANDITS POSSIBLE HORMONAL MEDIATORS IN CHILDREN

This study examines the effects of severe head injury in children on w hole body energy expenditure and the mediators that influence this. On e hundred five serial measurements of whole body energy expenditure an d plasma adrenaline, triiodothyronine, glucagon, cortisol, insulin, an d growth hormone concentrations were made in 18 children aged 2-15 y r eceiving neurointensive care for severe head injury. Energy expenditur e was measured using indirect calorimetry by a modified Douglas bag te chnique, and hormones were measured by RIA or radioenzymatic assay. En ergy expenditure varied markedly between and within children (mean 97% of predicted, range 60-137%) and was significantly lower in the four children with a poor outcome (p = 0.03). Within each child there were statistically significant positive relationships between energy expend iture and adrenaline (p < 0.0001), triiodothyronine (p < 0.0001), and glucagon (p < 0.0001). However, there was evidence that the effect of adrenaline on energy expenditure was attenuated. This may be due to th e effects of the cerebral trauma itself on central nervous influences on energy expenditure, to interactions between hormones, or to a globa l impairment of O-2 utilization by the body's tissues.