[Local anesthetic level and cardiovascular changes following local anesthesia in cataract operations with 3%...

Are there toxic plasma levels of mepivacaine after local anesthesia for ophthalmic surgery with 3% mepivacaine? What hemodynamic changes occur during injection of the local anesthetics? Fifteen patients undergoing cataract surgery were given 10 ml of mepivacaine (3%) as a local anesthetic regardless of body weight. After inserting an arterial line, blood samples were taken before the beginning of the injection of mepivacaine and after 3, 5, 10, 15, 30, and 60 min. Concentrations of the drug were measured by gas chromatography. During the first 15 min arterial blood pressure and ECG were registered continuously on a multichannel recorder. The maximum mepivacaine plasma levels were estimated after 15 min with a range from 0.28 to 6.95 micrograms/ml (means +/- SD: 4.5 +/- 1.47 micrograms/ml). The blood pressure was elevated over the preoperative value, at the beginning of the evaluation period, but there was no change in the blood-pressure level over the whole period. In 4 patients without known cardiac arrhythmias, ventricular or supraventricular extrasystoles occurred. The mepivacaine plasma levels complied with resorption kinetics, which is an indication that there were few intravascular injections and that the injection technique war correct. On the other hand, in some patients the mepivacaine plasma levels exceeded the toxic level. Even in ophthalmic surgery, local anesthetics should be given in relation to the body weight of the patients. The high blood-pressure levels indicated non-optimal preoperative treatment of the hypertonic patients, which was followed by an intraoperative exacerbation of the blood pressure.