xenon anaesthesia cerebrotoxic? - A comparative study with halothane
using protein S-100 determination
Introduction: S-100 is a protein that is found in high concentration in the nervous system of vertebrals. Structural damages to the glia cells cause leakage of protein S-100 into the extracellular compartment and finally into the serum, where the B-subunit of protein S-100 can be measured by a chemiluminescence assay.
We have investigated the effects of 70% xenon inhaled in 30% oxygen on the cerebral integrity measured by protein S-100 serum levels in 8 pigs (German landrace,weight of 47,7±4,85 kg). Anaesthesia was performed using a Cicero respirator adapted for administration of xenon (Dräger, Germany) with complementation of continuous infusion of buprenorphin 15 mgkg-1h-1 (anaesthesia time 129±28 minutes). As a self controling model each animal received 1 MAC halothane for 104±19 minutes before or after xenon anaesthesia in a randomized cross over design to eliminate systemic errors.
Materials and Methods: Arterial blood samples for S-100 analysis were taken under TIVA immediately before (X0/H0), 60 minutes after beginning (X1/H1) and at the end of xenon or halothane anaesthesia (X2/H2) and compared with a reference S-100 value measured before induction of anaesthesia (pre-value). All samples were centrifuged and frozen for batch analysis. Surgical stimuli were not present during xenon and halothane anaesthesia, surgical preparations were completed in total intravenous anaesthesia using continuous pentobarbital infusion at a rate of 15 mg/kg/h combined with buprenorphin at a rate of 15 mg/kg/h. Between xenon and halothane TIVA was applied to eliminate the effects of the anaesthetic gas applied first.
Results: At baseline measuring point in xenon and halothane anaesthesia all determined vital parameters like heart rate, i.a. blood pressure, cardiac output, central venous pressure, peripheral oxygen saturation and arterial blood gas samples were within physiological normal range and did not significantly change over time and there was no significant difference between the xenon and halothane group. Median values of protein S-100 at corresponding measuring points were not significantly different between the groups. Compared to the pre-values there was also no significant difference.
Discussion: We have found no significant difference between S-100 values in xenon or halothane anaesthesia. In addition, there was no increase in S-100 values during xenon or halothane anaesthesia. S-100 values did not change significantly compared to levels in animals before anaesthesia. We may conclude that xenon does not impair cerebral integrity compared to halothane anaesthesia, which is essential for a safe use of xenon as anaesthetic gas in the clinical practice.
Keywords: Xenon, inhalation, anaesthesia, protein S 100
Applied Cardiopulmonary Pathophysiology 9: 87-90, 2000
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