Volume kinetics of glucose 2.5% solution during laparoscopic cholecystectomy.

BACKGROUND

Analyses of the distribution and elimination of glucose 2.5% solutions can be used to suggest combinations of infusion rates and infusion times which yield a predetermined plasma glucose level and degree of plasma dilution during surgery.

METHODS

Twelve patients aged between 27 and 51 (mean 40) underwent laparoscopic cholecystectomy. An i.v. infusion of 1.4 litres of glucose 2.5% over 60 min was started when surgery began. A volume kinetic model was fitted to measurements of the plasma glucose concentration and the degree of haemodilution. Nomograms were constructed based on the kinetic results.

RESULTS

The volume of distribution for the glucose and infused fluid and the plasma insulin levels were similar to the ones recorded in previous volunteer studies, but 50-70% lower values were obtained for the clearance of glucose (mean 0.21 litres min(-1)), endogenous glucose production (1.1 mmol min(-1)) and the elimination rate constant for the infused fluid (median 37 ml min(-1)). Urinary excretion was markedly depressed and amounted to 9% of the infused fluid volume 4 h after starting surgery. To prevent hyperglycaemia, nomograms suggested that the infusion should be directed towards a "target" glucose concentration and then slowed down in a controlled way. At steady state, the infused fluid maintains a 3.5% plasma dilution for each mmol that plasma glucose remains above baseline.

CONCLUSION

Metabolic changes warrant careful balancing of infusion rates of glucose 2.5% during laparoscopic cholecystectomy, which is facilitated by a nomogram. Volume expansion from the infused fluid volume should be recognized.