A Variant for calculating ketamine infusion in manual total intravenous anesthesia

Abstract

Introduction: A requirement in the manual conduction of total intravenous anesthesia is the need to make temporary dosage adjustments to avoid drug accumulation in plasma. For some years there has been interest in using other drugs such as ketamine.
Objectives: To compare the temporal variation of ketamine concentration in plasma when applying a variant for calculating the decrease in the infusion rate (Vinf) with an invariable infusion rate.
Methods: An analytical study was carried out describing the dosage calculation for manual total intravenous anesthesia, the pharmacokinetic simulation of the behavior of ketamine concentration in plasma in case of being invariably administered with these dosing regimens, in a virtual patient, of 70 kg, according to the Domino model and the analysis of the variant for calculating the decrease of ketamine infusion rate. A statistical significance of 95% was estimated (p<0.05).
Results: The variant for calculating the decrease of the infusion rate: Vinf (tn) = Vinf (tn-1) _ [(Vinf (tn-1) x e (1+1/t) t)/100] = Vinf (tn -1) x 0.85 allowed more stable values of plasma concentration, which approximate that of the ideal model (p>0.05), for a time of 6 hours.
Conclusions: Probably, the decrease of the ketamine dose, established by the proposed calculation and infusion variant, allows better stability of plasma concentration.