BLOOD LOSS AND THROMBOEMBOLISM

BLOOD LOSS AND THROMBOEMBOLISM

Epidural anesthesia, when compared to general anesthesia, has been
associated with a decrease in intraoperative blood loss during orthopedic,
urologic, gynecologic, and obstetric procedures. When lumbar epidural
analgesia with bupivacaine has been extended into the postoperative
period after total hip replacement, ostoperative blood loss has also
with EAA are presumed to be (1) a decrease in mean arterial pressure,
(2) redistribution of blood flow away from the operative site to other
tissues, and (3) a decrease in venous pressure due to the elimination of
positive pressure ventilation. These mechanistic factors can probably
only be achieved with epidural local anesthetic administration. Avoidance
of intubation and positive pressure ventilation probably plays a
critical role in decreased blood loss with epidural anesthesia in pelvic
urologic and gynecologic surgeries.

Lumbar epidural anesthesia for total hip replacement has been
definitively shown to reduce the incidence of deep vein thrombosis and
even pulmonary embolism.34 Moreover, Sharrock et a139 conducted a
large retrospective review of in-hospital mortality after total hip and
total knee arthroplasty to determine whether changes in anesthesia care
from GA to predominantly epidural anesthesia were associated with
changes in mortality rates. They found a significant reduction in mortality
due to pulmonary emboli with a change from general anesthesia
(0.39% mortality; 23 of 5874 patients) to epidural anesthesia (0.1% mortality;
10 of 9685 patients; P = 0.0003). Mechanistic factors involved in
preventing the development of deep vein thrombosis (DVT) and subsequent
pulmonary embolism include sympathetic blockade resulting in
increased blood flow to the lower extremities, as well as prevention of
the hypercoagulable condition seen with general anesthesia and preservation
of baseline fibrinolysis.