[An infusion model for intraoperative peridural anesthesia by catheter using mepivacaine]

With the introduction of repetitive or continuous catheter techniques in regional anaesthesia, potential systemic intoxication hazards have increased. Especially high dose techniques such as peridural anaesthesia or plexus brachialis blockade consecutively generate high blood levels. In this study, blood levels collected from 20 patients (36 +/- 19 y, 173 +/- 9 cm, 73 +/- 15 kg) after lumbar epidural anaesthesia with mepivacaine led to the development of a linear open one-compartment-model (VD,ss: 109 l, Cltot: 594 ml/min, t1/2abs: 13 min, t1/2 beta: 149 min). With that model, dosage strategies could be studied via computer simulation. A mepivacaine dosage regimen for lumbar epidural anaesthesia, consisting of 250 mg as an initial bolus dose and an infusion rate of 150 mg/h after 15 min, cumulated to maximum concentrations of 2.5-3.5 micrograms/ml after 150 min. Such an infusion regimen may lead to concentrations of more than 4 micrograms/ml if applied for longer than 4 h. The pharmacokinetic computer simulation proved to be precise and could be compared to the measured blood levels of mepivacaine.