SYSTEMATIC REVIEWS IN REGIONAL ANAESTHESIA:
REGIONAL ANAESTHESIA AND OUTCOME
Andre Van Zundert
Catharina Hospital – Brabant Medical School
Eindhoven – The Netherlands
Central neuraxial and peripheral blockades are widely used to manage surgery and postoperative
analgesia, but its risks and benefits are uncertain.
Several perioperative modalities have been said to reduce morbidity after major surgery, including
the use of regional anesthesia rather than general anesthesia, perioperative invasive
hemodynamics, and perioperative epidural analgesia.
Whether epidural anesthesia and analgesia improve the outcome of major abdominal surgery is a
long-running controversy. Many beneficial aspects of epidural anesthesia have been reported,
including more stable cardiovascular hemodynamics, better peripheral vascular circulation, better
suppression of surgical stress, positive effect on postoperative nitrogen balance, and better
postoperative pain control. Perhaps the explanation can be found in the fact that general
anesthesia leads to an intense afferent activity in CNS triggers. This neuro-endocrine action is called
the "stress response", which leads to hypercoagulability.
Postoperative cardiac morbidity and mortality continue to pose considerable risks to surgical
patients, as myocardial infarction is a leading cause of postoperative morbidity. Epidural analgesia
is considered to have beneficial effects on cardiac outcomes. However, the use in high-risk cardiac
patients remains controversial. Beattie (2001) demonstrated in a meta-analysis study of 1.173
patients that postoperative thoracic epidural analgesia showed a significant reduction in postmyocardial infarction.
Α meta-analysis of randomized controlled trials (Rodgers, 2000) found that, compared with other
analgesic techniques, neuraxial block was associated with significantly decreased perioperative
morbidity and mortality. Venous thromboembolism (50% reduction), myocardial infarction (33%
reduction), pneumonia (39% reduction), postoperative respiratory depression (59% reduction) was
found in the studied population, with a 50% lower chance on bleeding complications.
Α review article on the prevention of perioperative myocardial ischemia following surgery,
recommends inhibition of sympathetic nervous system activity (WarltieI, 2000). Furthermore, there
is growing evidence that for major non-cardiac surgery, outcome is improved when regional
anaesthesia, which provides sympathetic blockade, is employed (Buggy, 1999).
High thoracic epidural analgesia (Τ1 to Τ5) results in a reduction of the heart rate, improves
ischemia-induced left ventricular dysfunction, reduces signs of coronary insufficiency, decreases the
incidence of arrhythmias and improves the myocardial oxygen supply-demand balance. Lower
thoracic and lumbar epidural anesthesia results in a peripheral sympathetic blockade together with
a block of the splanchnic fibers, producing vasodilation in the blocked areas and compensatory
vasoconstriction in the remaining unblocked areas. Scott (2001) demonstrated beneficial effects of
thoracic epidural anesthesia in patients undergoing coronary bypass grafting: earlier extubation,
better postoperative pulmonary function, fewer lower respiratory tract infections, less arrhythmias
and a lower incidence of stroke and renal failure.
Pulmonary effects of epidural anesthesia are a result of the blockade of sympathetic and intercostal
nerves and the interruption of an inhibitory reflex of the phrenic motor nerve drive. Α substantial
reduction in deep vein thrombosis and pulmonary embolism, arrhythmias and myocardial infarction
was demonstrated in the meta-analysis studies of Rodgers (2000) and Beattie (2001). An increased
alveolar ΡΟ2 and a decreased incidence of pulmonary infections and overall pulmonary
complications could be demonstrated by Ballantyne (1998).
Park (2001) found in over 1000 patients undergoing abdominal aortic operations, that adequate
epidural analgesia results in a shortened intensive care stay. It is important to know the target of
the epidural: up to Τ4, or Τ6 level, and that the epidural is kept in place for 48 hours or even longer.
Patients may ambulate earlier and oral feedings can be initiated at an earlier stage. Rigg (2002)
found in a similar group (915 patients) that most adverse morbid outcomes are not reduced by the
use of the combined spinal epidural anesthesia intraoperatively and the epidural catheter
postoperatively. However they found improvement in analgesia, reduction in failure rate and a low
risk of serious adverse consequences if the patients are treated with an adequate epidural
technique, applying continuing postoperative epidural analgesia (MASTER study). Peyton (2003)
however, could not find evidence that perioperative analgesia significantly influences major
morbidity and mortality after major abdominal surgery, apart from respiratory failure. This study
group comprised of 915 high risk patients.
Especially in orthopedic surgery the combined use of central neuraxial blocks and peripheral blocks
resulted in a faster rehabilitation (Singelyn, 1998 - Capdevilla, 1999). Α recent study of Neal and coworkers (2003) found that a suprascapular nerve block with bupivacaine, as an adjunct to an
interscalene block combined with general anesthesia, does not improve outcome measures after
ambulatory surgery of the shoulder.
There are many study problems when interpreting meta-analysis studies: sample size too small,
poor or no randomization, too many types of surgery, lack of power to demonstrate differences,
too many variables, too many confounding variables such as technique, type and quantity of local
anesthetics, addition of opioids, the level of epidural placement, postoperative management may
differ (ambulation, feeding, physiotherapy), ...
But what is relevant? Is regional anesthesia advantageous over general anesthesia in young healthy
patients undergoing surgery on one of the limbs? Is reduced mortality really a good reason for this
patient category? Even in a 50 or 60-year-old healthy patient undergoing peripheral orthopedic
surgery accompanied by minimal blood loss, will it be difficult to prove that regional anesthesia has
advantages over general anesthesia. Many of the outcome studies have focused on big outcomes
such as: death, blood loss and transfusion requirements, and cardiovascular and pulmonary
complications.
From the patients point of view the positive points are absence of postoperative sedation, a rapid
recovery, less PONV, excellent pain control, and the ability to ambulate (and feed) earlier. Some
patients value regional anesthesia as they do not lose control of themselves, an unavoidable aspect
of general anesthesia.
Are we, Anesthesiologists, doing the job right?
We have to insert a thoracic epidural catheter, give a good quality block blocking the nociceptive
impulses during the surgical intervention and in the postoperative phase (up to three days). If a
patient is pain free in the postoperative phase he is more in for physiotherapy, earlier ambulation
and earlier feeding, as the patient feels more comfortable. Α reduced morbidity and an accelerated
convalescence can be obtained if a multimodal approach is applied in which the patient is
adequately informed and prepared, where an appropriate epidural catheter technique is used, not
only to provide intraoperative pain relief, but also to relief pain in the postoperative period. As such
perioperative stress is attenuated, while the patient may recover earlier, due to earlier active
exercises and an earlier start of enteral nutrition.
It is hard to believe that regional anesthesia is beneficial in every patient and in every surgical
intervention. However, common sense makes us to believe that some surgery (cataract, hip surgery,
prostate surgery, Cesarean section, several extremity operations, ...) are best performed under
regional anesthesia. This means that a wide variety of patient populations undergoing surgery, is
satisfied and often chooses the same regional anesthesia if they have to come a second time for an
operation. Surgical outcome however is not only determined by anesthesia alone. Postoperative
care (pain relief, early recovery, faster return of gastrointestinaI function and feeding, ability to
return to work or to their former lifestyle) is dependent on many other factors. Early
thromboprophylaxis and perioperative β-blockade also proved their value.
Epidural anesthesia is not a cure for pre-existing morbidity that may contribute to postoperative
complications. One cannot reduce death from severe coronary artery disease with a short-term
intervention.
Although it may be difficult to prove that regional anesthesia has major advantages on all aspects
over general anesthesia, there is no study where general anesthesia has proven meaningful
outcome improvements over regional anesthesia.
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