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Blood levels of mepivacaine during continuous epidural anesthesia
Abstract:
Venous blood concentrations of mepivacaine were measured in 30 patients during 5 hr of surgical anesthesia following either multiple epidural injections of mepivacaine with or without epinephrine or continuous epidural infusion of mepivacaine with epinephrine. Patients were divided into three groups: group 1 initially received 10 or 15 ml followed by 10 ml of 2% plain mepivacaine at 1-hr intervals; group 2 received 10 or 15 ml followed by 10 ml of epinephrine-containing 2% mepivacaine at 1-hr intervals; group 3 received 10 or 15 ml followed by a constant infusion of 10 ml/hr of epinephrine-containing 2% mepivacaine. There were no significant differences between groups 1 and 2, but the mean blood concentration was slightly lower for the first 3 hr in group 2 than group 1. The mean blood concentration of mepivacaine in group 3 remained significantly lower than the concentrations in groups 1 and 2 from 3.5 to 5 hr. These results demonstrate that the blood concentrations of mepivacaine are not reduced by the addition of epinephrine to mepivacaine solutions when intermittent epidural injections are repeated more than four times at 1-hr intervals, but that blood mepivacaine levels are reduced below levels seen with intermittent injections by the continuous epidural infusion of epinephrine-containing mepivacaine.
Insights
Continuous epidural infusion of mepivacaine with epinephrine significantly lowers blood concentrations compared to intermittent injections. Epinephrine addition to intermittent mepivacaine epidural injections did not substantially reduce blood levels.
Area of Science:
- Anesthesiology
- Pharmacology
- Surgical Care
Background:
- Mepivacaine is a local anesthetic used in surgical anesthesia.
- Epinephrine is often added to local anesthetics to prolong their effect and reduce systemic absorption.
- The impact of continuous infusion versus intermittent injections of mepivacaine with epinephrine on blood concentrations requires further investigation.
Purpose of the Study:
- To compare venous blood concentrations of mepivacaine during surgical anesthesia.
- To evaluate the effects of intermittent epidural injections versus continuous epidural infusion of mepivacaine with and without epinephrine.
Main Methods:
- 30 patients undergoing surgical anesthesia were divided into three groups.
- Group 1: intermittent plain mepivacaine epidural injections.
- Group 2: intermittent mepivacaine epidural injections with epinephrine.
- Group 3: continuous epidural infusion of mepivacaine with epinephrine.
Main Results:
- No significant difference in mepivacaine blood concentrations between intermittent plain mepivacaine (Group 1) and intermittent mepivacaine with epinephrine (Group 2).
- Slightly lower initial blood concentrations in Group 2 compared to Group 1 for the first 3 hours.
- Significantly lower mepivacaine blood concentrations in the continuous infusion group (Group 3) compared to both intermittent groups from 3.5 to 5 hours.
Conclusions:
- Adding epinephrine to mepivacaine does not reduce blood concentrations with frequent intermittent epidural injections.
- Continuous epidural infusion of mepivacaine with epinephrine leads to lower systemic absorption compared to intermittent injections.