Uptake and elimination of sevoflurane in rabbit tissues - an in vivo magnetic resonance spectroscopy study

Purpose: Previous pharmacokinetic studies of fluorinated anesthetics using F-19-magnetic resonance spectroscopy (F-19-MRS) have focused on the brain. investigation of other tissues would give more precise information about th e pharmacokinetics of inhalational anesthetics. In this study we investigat ed the pharmacokinetics of uptake and elimination of sevoflurane in brain; liver, muscle, venous blood and arterial blood of rabbits. Methods: Twenty rabbits were examined by F-19-MRS conduced at 4.7 Tesla usi ng a 1-cm-diameter surface coil for brain (n=4), liver (n=5) and muscle (n= 5), and a 1.3-cm-diameter surface coil for arterial (n=3) and venous (n=3) blood. Sevoflurane, 4% in oxygen, was administered for 120 min, followed by 120 min elimination. Results: Both the uptake and elimination kinetics were best fitted by a bie xponential curve which was divided into fast and slow components. During th e uptake experiment the time required to reach half of the maximum spectros copic intensity in each tissue was 1.6 min in arterial blood, 4.7 min in li ver, 12.2 min in venous blood, 14.4 min in brain and 20.9 min in muscle. Du ring the elimination experiment the time required to reach half maximum int ensity was 2.4 min in arterial blood, 6.3 min in liver, 13.4 min in venous blood, 19.6 min in brain and 28.7 min in muscle. Conclusions: Sevoflurane uptake or elimination in the tissues examined foll owed biexponential kinetics. In this rabbit model, sevoflurane uptake and e limination were fastest:in arterial blood, followed, in order, by liver, ve nous blood, brain and muscle.