Effect of increasing intravenous glucose load in the presence of normoglycemia on outcome and metabolism in critically ill rabbits

Introduction

Endocrine disturbances during critical illness lead to a feeding-resistant wasting syndrome, characterised by profound protein breakdown, promoting delayed recovery and poor outcome. Parenteral nutrition failed to counteract the hypercatabolic state, possibly due to aggravation of the detrimental hyperglycemic response to critical illness. In our rabbit model of prolonged critical illness we investigated the impact of varying intravenous glucose load, while maintaining normoglycemia, on mortality, organ damage, and catabolism/anabolism.

Methods

Critically ill rabbits were randomised into a fasting group, a standard parenteral nutrition group, and two groups receiving either an intermediate or high additional amount of intravenous glucose within the physiological range, all maintained normoglycemic with insulin. These normoglycemic groups were compared with a hyperglycemic group (similar high glucose load as the last normoglycemic group) and with healthy rabbits. Protein and lipid load was equal for all fed groups.

Results

Varying intravenous glucose load did not affect the mortality or organ damage, provided normoglycemia was maintained. Fasted critically ill rabbits lost weight, which was attenuated by increasing intravenous glucose load. As compared with healthy rabbits, mRNA expression of several components of the ubiquitin–proteasome pathway was elevated in skeletal muscle of fasted critically ill rabbits, which was counteracted by intravenous feeding. Except in the normoglycemic group with intermediate glucose load, circulating insulin-like growth factor 1 and thyroid hormone levels decreased in all groups, most pronounced in hyperglycemic rabbits.

Conclusion

Provided normoglycemia is maintained, increasing intravenous glucose within the physiological range is safe for organ function and survival of critically ill rabbits and reduces catabolism compared with fasting.