Introduction. Thoracic epidural analgesia, combined with general anesthesia,
is an established anesthetic choice for abdominal aortic surgery. However,
there are controversies about the level of anesthesia as well as the dose and
concentration of the local anesthetic used. The aim of the study was to
compare the effects of two different concentrations of epidural bupivacaine
on sevoflurane requirements and hemodynamic parameters during aortic surgery
under combined epidural/general anesthesia. Methods and Material. Sixty
patients scheduled for abdominal aortic surgery were randomly divided into
two groups according to the concentration of local anesthetic used for
epidural anesthesia: - Group 1- low concentration - where 0.125% bupivacaine
was used, and - Group 2 - high concentration - where 0.5% bupivacaine was
used at the beginning and then the concentration was reduced to 0.25%.
Anesthesia was maintained with sevoflurane, the dose was adjusted to achieve
the target entropy of 40-60. The measurements included the inspired
sevoflurane concentrations, blood pressure, and heart rate at the beginning
and every 5 min during the surgery. Results. Both groups had similar heart
rate and blood pressure, but the inspired sevoflurane concentration was
significantly higher and more variable in patients where bupivacaine 0.125%
was used. Vasopressors were used more often and in higher doses in the 0.5%
bupivacaine group, and in the same group the blood loss and fluid
requirements were reduced. Conclusion. When 0.5% bupivacaine is used in
combined thoracic epidural/ general anesthesia for aortic surgery, the
sevoflurane concentrations are lower and less variable. In addition, the
blood loss and fluid requirements are reduced.
Effects of epidural analgesia using different concentrations of bupivacaine during combined general and epidural anesthesia