6533b834fe1ef96bd129d403

RESEARCH PRODUCT

Thiopentalkonzentrationsverlauf im Vollblut von schwangeren und nichtschwangeren Patientinnen in den ersten Minuten nach der Injektion

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Thiopentone concentrations in blood following injection of the induction solution (Thiopental, 2.5%) may be critical in the context of lethal complications arising during induction of anaesthesia and thereby the toxicological aspects of this drug can become an issue in forensic considerations. The study was designed to find out whether the dose of injected thiopentone may be calculated from blood levels measured in nine pregnant and ten non-pregnant patients. The doses injected ranged from 4-5 mg per kg body weight. The drug was administered as a single bolus dose to the patients undergoing Caesarean section. In the non-pregnant group the first dose of thiopentone was given over 25 s. After that repeated doses of 50 mg were injected over 2s every 20s until the eyelid reflex was ceased. Blood samples for determination of thiopentone were withdrawn from an indwelling catheter inserted to a large cubital vein in the arm opposite that used for the injection and thiopentone levels were measured from blood after column extraction (Extrelut) using spectrophotometry. Venous peak values were found 40-115s after injection in the Caesarean group (mean: 20.3 micrograms kg-1) and were higher than in the non-pregnant patients (97-190s, mean: 17.8 micrograms kg-1). No correlation was found regarding venous peak levels (mgkg-1 blood) and induction dose (mgkg-1 body weight), neither in the pregnant nor in the non-pregnant group. Our findings would suggest that the injected thiopentone dose cannot be calculated from the concentration of the drug in the blood. Forensic conclusions concerning the onset of lethal complications during the induction of anaesthesia cannot be drawn on the grounds of venous thiopentone concentrations.