Blood concentrations of tetracaine and its metabolite following spinal anesthesia.

Blood concentrations of tetracaine and its metabolite, p-butylaminobenzoic acid, were measured after spinal anesthesia with tetracaine which had been administered to patients under going orthopedic surgery. Tetracaine, an ester anesthetic, was given to 10 patients, the dose was 8-14mg, and blood samples were collected 1, 2 and 6h after the injection of tetracaine. We used gas chromatography/mass spectrometry for purposes of analysis. Tetracaine was not detected in any blood sample, but the metabolite was detected in each sample with the mean concentrations of 126.5, 97.9 and 43.3ng/ml at 1, 2 and 6h, respectively. This data will be useful in determination of the cause of death after spinal anesthesia with tetracaine.

Valoración cinética y dinámica de la lidocaína y mepivacaína en odontopediatría / Kinetic and dynamic evaluation of lidocaine and mepivacaine in pediatric dentistry

En una población pediátrica de 20 niños se evalúa el comportamiento cinético y dinámico dela lidocaína y mepivacaína asociados con adrenalina, con referencia específica al período de latencia, profundidad y duración del efecto anestésico

Lung uptake of lidocaine in man as influenced by anaesthesia, mepivacaine infusion or lung insufficiency.

Pulmonary uptake of lidocaine was investigated in patients before surgery, and aimed at elucidating the influence of general anaesthesia, the presence of another local anaesthetic agent in the blood, or the possible impact of lung insufficiency. When the lung uptake of lidocaine, injected as a bolus together with indocyanine green dye, was calculated as uptake at 95% pass of the dye, there were no statistically significant differences between the four groups. When the extraction in each of the arterial blood samples was calculated on the basis of the relation between relative concentrations, there were statistically significant differences, with a general tendency towards higher extraction of lidocaine in the awake, healthy volunteers, not given mepivacaine, compared to the other groups. In the group in whom mepivacaine was infused, the arterial concentration of mepivacaine increased transiently after the injection of lidocaine. This probably reflects a displacement of mepivacaine from binding sites for both agents. From this study, it is postulated that the ability of the pulmonary circulation to clear the blood of lidocaine is high, and that it is not affected markedly by those situations studied in the present investigation.

Studies on the duration of local anesthesia: a possible mechanism for the prolonging effect of "vasoconstrictors" on the duration of infiltration anesthesia.

Attempts have been made to correlate the duration of the local anesthetic effect with the amount of the local anesthetic compound remaining at the injection site at different times after an injection. In addition to delaying the absorption of the local anesthetic, adrenaline but not a vasopressin-derivate decreased the minimal anesthetic concentration of the local anesthetic agent. It is assumed that the pH value of the tissues at the injection site was kept down through the metabolic effects of adrenaline, thereby transforming the local anesthetic agent into cations, which is the form in which the amide-type of local anesthetics mainly exerts their nerve blocking activity.

Studies on the duration of local anesthesia. Effects of volume and concentration of a local anesthetic solution on the duration of dental infiltration anesthesia.

In animals and humans the rate of resorption and the duration of the anesthesia have been investigated, using mepivacaine in different concentrations and volumes without addition of a vasoconstrictor. A linear relationship between duration of anesthesia and the logarithm to the concentration of mepivacaine was found.

An inhibitory effect of polyphloretin phosphate (PPP) on local anaesthesia.

In the present investigation it is shown that administration of polyphloretin phosphate (PPP) together with local anaesthetics decreased the duration of infiltration anaesthesia in guinea-pigs. Furthermore, it is shown that in infiltration anaesthesias the local anaesthetic effect was terminated within a few minutes by administration of PPP. In experiments with high- and low-molecular fractions of PPP, the "anti-local anaesthetic" effect of PPP was not due to the antiprostaglandin activity of PPP. There was no effect of PPP on the duration of the nerve-blocking activity of mepivacaine in rats. Neither did the administration of PPP influence the toxic effects of mepivacaine in rabbits.