Anesthesiology
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Comparative Study
Absence of agonistic or antagonistic effect of flumazenil (Ro 15-1788) in dogs anesthetized with enflurane, isoflurane, or fentanyl-enflurane.
This study determined the effects of flumazenil on the anesthetic requirements (MAC) of the dog for isoflurane (group 1; n = 6), enflurane (group 2; n = 7), and a combination of fentanyl-enflurane (group 3; n = 6). Control MAC in each group was determined by the tail-clamp method. Each animal in groups 1 and 2 received four iv incremental doses of flumazenil: 0.5, 1.0, 1.5, and 4.5 mg/kg, and isoflurane MAC or enflurane MAC was determined after each dose. ⋯ In group 3, plasma fentanyl concentrations remained stable at 12.5 +/- 3.0 ng/ml (mean +/- SD) throughout the experiment and reduced enflurane MAC by 60 +/- 8%. The addition of flumazenil changed neither the fentanyl concentration in plasma (12.2 +/- 3.8 ng/ml) nor its reduction of enflurane MAC (61 +/- 7%). In conclusion, the absence of effect of flumazenil on the MAC of enflurane, isoflurane, or a fentanyl-enflurane combination suggests that they do not interact with the benzodiazepine receptor.
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The incidence of failed local anesthetic axillary blockade varies but can be as high as 20-30%. The authors propose to evaluate the safety of supplementing an axillary block with mepivacaine 30 min after the initial injection. An axillary blockade was performed on 10 healthy patients scheduled for forearm or hand surgery using a new catheter technique. ⋯ Plasma levels of mepivacaine were estimated at frequent intervals for 5 h after the initial injection. There were no symptoms or signs of local anesthetic toxicity, and plasma levels of mepivacaine remained below those that usually caused symptoms. In conclusion, the authors conclude that mepivacaine 1% with epinephrine (10.5 mg/kg) can be safely administered in divided doses into the axillary sheath within a 31-min period.
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Clinical Trial
The cardiovascular effects of mivacurium chloride (BW B1090U) in patients receiving nitrous oxide-opiate-barbiturate anesthesia.
The dose-effect relationship of mivacurium chloride on arterial blood pressure, heart rate, and plasma histamine was determined in 97 consenting ASA physical status I-II patients receiving nitrous oxide-oxygen-opiate-barbiturate anesthesia. In the absence of surgical stimulation during steady state anesthetic conditions with controlled ventilation, average maximum change in tachograph-counted heart rate was 7% or less after 10-15-s injection of mivacurium at all doses from 0.03 to 0.30 mg/kg. Average peak change in mean arterial pressure measured via radial arterial catheter was 7% or less after all doses from 0.03 to 0.15 mg/kg. ⋯ For example, mean blood pressure decreased an average of 13% after injection of mivacurium 0.25 mg/kg over 10-15 s. In contrast, during administration over 30 and 60 s of this dose, arterial pressure decreased 7.6 and 1.5%, respectively (P less than 0.001, 10-15 s vs. 60-s injection). Average peak histamine level, which increased to 132% of control after administration of 0.25 mg/kg over 10-15 s, did not change after injection over 60 s.(ABSTRACT TRUNCATED AT 250 WORDS)