Effects Specific to Epidural Anesthesia
The physiologic effects of epidural anesthesia are similar to
those of spinal anesthesia, with the exception that
Figure 43-7
Meperidine requirements during the first and second postoperative
days in patients receiving intravenous lidocaine (filled bars)
and in control patients (open bars). Data are expressed
as the mean ± SEM. *, p < .02; **,
p < .01 compared with control data. (Adapted
from Cassuto J, Wallin G, Högström S, et al: Inhibition of postoperative
pain by continuous low-dose intravenous infusion of lidocaine. Anesth Analg 64:971,
1985.)
local anesthetic blood levels reach concentrations sufficient enough to produce systemic
effects on their own. Even intravenously administered lidocaine (resulting in blood
levels similar to those after continuous epidural analgesia) can decrease postoperative
narcotic requirements ( Fig. 43-7
).
[58]
When blood levels are excessive, adverse CNS
and cardiovascular effects occur (see Chapter
14
).
