Blog with interesting cases and/or problems related to anesthesia with discussion based on best evidence in the literature.

May 8, 2013

neuraxial anesthesia and outcomes

This months Journal of Anesthesiology contained an article where the authors found that the utilization of neuraxial anesthesia either alone or combined with GETA lowered 30 day mortality after total joint replacement (TKA or THA) [1].  This comes after two other recent studies showed lower SSI after TKA or THA [2] and lowered incidence of admission to the ICU [3].  The search for a benefit in hard outcomes (i.e. mortality and major morbidity) for patients receiving regional anesthesia w/ or without GETA is been frought with problems.  Early studies were able to decisively show reduced morbidity with neuraxial anesthesia after major general surgical cases. In 1987, Yeager et al. was able to show a reduced mortality and morbidity, including lower infectious complications in high risk surgical patients who also had epidural analgesia.  Cardiac morbidity was also lower in this study.  Unfortunately, a mid study review of the data was so clear cut as to improved benefit, that the study was halted early. In 2000, a meta-analysis was published by Rogers et al. showing reduced mortality and morbidity when epidural analgesia was used.   However, results and conclusions have been questioned by some authors due to a great deal of heterogeneity in the various studies included in the meta-analysis.  Two years later, Riggs et al. published a large prospective RCT in the Lancet where 30 day mortality was not different between patients who received epidural analgesia with or without GETA or just GETA.  They did find that pulmonary complications (PaCO2 >50 mmHg) was reduced in the EAA group, and pain scores were much better in the EAA group.  Some authors question these results claiming that site of epidural placement was not dictated by the study protocol, but rather, left to the discretion of the individual anesthesiologist.  Obviously, a non working epidural, because it was placed at improper level is problematic.  Furthermore, Mortality was low in both groups at 30 days, which means the study was likely not adequately powered.  After this study, the anesthesia community resigned itself to the fact that we could not offer epidural anesthesia after abdominal surgery to patients claiming that there chances of dying would be reduced.  We could tell them that the likelihood for respiratory failure would be lower and that pain control would be superior.  Furthermore, other studies have shown that bowel function returns to normal more quickly when epidural analgesia is used in the post operative period with local anesthetics compared to IV PCA.  A cochrane analysis concluded that post operative ileus is reduced when local anesthetics are infused into the epidural space.  However, newer peripheral Mu opioid receptor antagonists are being introduced into practice.  These are reducing the incidence of post operative ileus by reversing the effects of intravenous narcotic on the mu-opioid receptor.  Therefore, it is not clear whether, epidural analgesia can still further reduce post operative ileus when patients are taking medications such as alvimopan.  Meta analysis of alvimopan phase III trials showed a significant improvement in time to first bowel movement, flatus, and toleration of solid food.   Recently, studies looking at regional anesthesia in cancer surgery have proposed that tumor recurrence may be reduced in patients having regional anesthesia.  In breast cancer patients undergoing mastectomy, 3 year recurrence and metastasis free survival was 82% in those who had a paravertebral block vs. 77% in those without [5].  Benefits were also found in prostate cancer surgery, but a RCT with epidural analgesia in abdominal surgery for cancer did not show any benefit.

Therefore, the recent study is important.  This study is important because it uses a large database capturing a very large number of cases for comparison.  While the study was retrospective, creating a prospective RCT large enough to capture a difference in mortality will likely be impossible.  This retrospective study also showed a number of benefits of neuraxial anesthesia.  This study demonstrated a lower incidence of pulmonary embolism, pulmonary compromise, pneumonia, cerebral vascular events and acute renal failure. Although cardiac morbidity was no different between groups, the transfusion burden was higher in the General anesthesia only group (15.15% vs. 18.53%).  Furthermore, median length of hospital stay was 2.6 days vs. 2.7 days (P<.001) in the neuraxial anesthesia vs. GETA group.  They also looked at prolonged length of stay and found that it was lower in the neuraxial anesthesia group (28.7% vs. 35.4%). 

Therefore, this study combined with recent studies that showed reduced infection risk and reduced admission to the ICU risk in patients who received neuraxial anesthsia for THA or TKA, makes the case ever stronger that first anesthesiologists play in a role in post operative outcomes that occur long after our involvement with the patient and that we need to take an active role in educating our surgeons and patients as to the benefits of neuraxial anesthesia.

1. Memtsoudis SG et al. Perioperative comparative Effectiveness of Anestheteic Technique in Orthopedic Patients.  Anesth. 2013; 118: 1046.

2. Chang C-C, Lin H-C, Lin H-W, Lin H-C: Anesthestic management and surgical site infections in total hip or knee replacement: A population-based study. Anesthesiology 2010; 113:279–84
3.  Memtsoudis SG et al. Utilization of critical care services among patients undergoing total hip and knee arthroplasty: epidemiology and risk factors.  Anesth. 2012; 117: 107.
4. Spahn DR.  Anemia and Patient Blood Management in Hip and Knee Surgery: A systematic Review.  Anesth.  2010; 113: 482.
5.  Exadaktylos AK. et al. Can anesthetic technique for primary breast cancer surgery affect recurrence or metastasis? Anesth. 2006; 105: 660.

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