[Study of metabolism in critically ill patients by indirect calorimetry]

Indirect calorimetry was performed in 48 postsurgical critically ill patients including those with multiple organ failure. The patients were divided into two groups, organ failure group (OF group) and postsurgical control group (C group), according to the presence of postsurgical organ failure and severe infection. The following results were obtained. The ratio of energy expenditure to basal energy expenditure, reflecting a degree of hypermetabolism, was 1.44 +/- 0.38 in OF group and 1.26 +/- 0.23 in C group respectively. The change in respiratory quotient by caloric intake was greater in OF group than in C group, indicating that it is more important to maintain an adequate intake for the prevention of increased respiratory work and excess lipogenesis in OF group. When nitrogen intake as amino acids was sufficient (0.1-0.2 g/kg/day), nitrogen balance could be maintained around 0 by a caloric intake being equal to measured energy expenditure. A positive correlation was observed between arterial ketone body ratio reflecting energy charge in hepatocytes and respiratory quotient, indicating that in patients with impaired mitochondrial function in hepatocytes as shown by a decrease in ketone body ratio, glucose cannot be utilized effectively. These results let us conclude that calorimetry is indispensable in the management of critically ill patients and that adequate energy intake should be cautiously determined according to the calorimetry.