Memtsoudis, Stavros G. MD, PhD, FCCP; Liu, Spencer S. MD
From the Department of Anesthesiology, Hospital for Special Surgery, Weill-Cornell Medical College, New York, New York.
Accepted for publication March 12, 2014.
The authors declare no conflicts of interest.
Reprints will not be available from the authors.
Address correspondence to Stavros G. Memtsoudis, MD, PhD, FCCP, Department of Anesthesiology, Hospital for Special Surgery, Weill-Cornell Medical College, 535 East 70th St., New York, NY 10021. Address e-mail to email@example.com.
A debate continues and has recently intensified among perioperative physicians on the question whether the technique used for anesthesia and/or analgesia can affect outcomes. Over the past decades, many attempts have been made to provide at least incremental evidence to support or refute the hypothesis that regional anesthesia and analgesia influences perioperative outcomes with definitive results still lacking.
In a review of the literature published in this edition, Kooij et al.1 provide a critical assessment of a number of studies on the topic and conclude that neither neuraxial nor regional techniques improve perioperative outcomes in general surgical patients. While this interpretation of reviewed studies seems soundly founded on the presented scientific evidence, the article also highlights the complexity of the issue at hand.
In this context, it is not surprising that in the presence of the same data sources, there are those who conclude that regional anesthetic and analgesic techniques can indeed improve outcomes after surgery. This phenomenon is intriguing because it suggests that the difference in opinion may be based more on the difference in vantage point rather than on an alternative scientific basis. What then may be the reasons for such a dichotomy in conclusion? In our opinion, a number of points need to be considered before drawing conclusions from the literature.
First, a major problem and source of confusion that burdens the interpretation of results is the blurry line drawn between the use of regional techniques for anesthesia and/or analgesia. Kooij et al.,1 recognizing the significance of this issue, have attempted to focus on the analgesic use, but this distinction is at best difficult to make, as evident by the inclusion of landmark publications such as that by Rodgers et al.2
After all, a regional technique used for intraoperative anesthesia may have a profound impact on subsequent analgesic needs, as suggested by the concept of preventive analgesia. Furthermore, neuraxial and regional anesthetics may suppress the stress response during the time of maximal injury and have long-term effects.
Perhaps such a distinction is indeed artificial and not even possible. It is a fact that many of the most frequently quoted studies have difficulties differentiating between the two from a purely methodological perspective, that is, it is often not clear what the purpose of the neuraxial/regional technique was. In this context, the systematic review performed by Guay et al.,3 which also appears in this month’s Anesthesia & Analgesia, suggests that the use of neuraxial compared with that of general anesthesia can affect 30-day mortality and the risk of pneumonia while positively influencing the latter outcome when neuraxial is added to a general anesthetic. Similarly, recent population-based analyses, targeted to investigate the impact of neuraxial anesthesia on perioperative outcomes in joint arthroplasty patients, must be mentioned because they have found significant reductions in mortality, cardiopulmonary, and other complications.4–7 It is interesting to note that none of these studies could identify whether perhaps the use of these neuraxial techniques was pursued for postoperative “analgesia” in addition to their “anesthetic” purposes.
Second, the number of patients included in most studies evaluating this subject is relatively small compared with the relatively low incidence of postoperative complications, thus limiting the power of even well-conducted meta-analyses, which are further burdened by inclusion of studies with high heterogeneity of populations and methodology. It is therefore not surprising that in the systematic review presented here by Guay et al.3 the authors conclude that larger sample sizes are needed to more definitively answer important questions on the topic. It must be pointed out, however, that in this3 as in most other studies on the topic, many effects that were found to not reach statistical significance did show a trend toward better outcome compared with that of control groups. The impact of the limited power of traditional studies and meta-analyses in this setting may have become more obvious in the era of large database research, which, despite many disadvantages, has the ability to employ much larger populations for analysis. However, the benefits associated with neuraxial techniques shown in these studies have also been criticized as being a function of very large sample sizes. Therefore, their clinical relevance in individual practice has been questioned.8 However, this viewpoint has to be countered by the fact that with tens of millions of surgeries performed in the United States alone every year, even small increments in outcome improvement or effect sizes may have substantial impact on a public health level. In the case of total joint arthroplasties, assuming some level of causality, the use of neuraxial instead of general anesthesia may relate to hundreds of lives saved and tens of thousands of complications averted, given the fact that over 1 million procedures are performed annually.4 This view of our specialty as a part of a population-based health care system should not be difficult to follow, especially because when it comes to assessing complications associated with neuraxial techniques, we have become accustomed to considering events that occur in the range of 1:10,000 to 1:200,000 as significant to our practice.
One final point to consider is the fact that while the literature can be interpreted as not sufficiently supporting the broad superiority of neuraxial techniques, especially analgesic ones, with respect to perioperative outcomes, one would be hard-pressed to conclude that outcomes are worse with regional techniques compared with alternative approaches, that is, general anesthesia or systemic analgesia.
In conclusion, while the literature on anesthetic and analgesic techniques and their effect on outcome is far from definitive, it is clear that the interpretation of studies depends on factors as simple as definitions chosen and as complex as the discussion regarding our role as anesthesiologists in the wider health care system.
As perioperative care has become complex, integrated, and is constantly changing, thus making it difficult for a single effect from a single component to be detected and isolated from the overall noise, alternative approaches to answer related questions may be needed. As such, practical clinical trials collecting large amounts of detailed observational data and using advanced analytical methodologies may bring at least incremental evidence to the debate. At the same time, it will be necessary to pursue studies identifying and documenting potential mechanisms by which these techniques can confer their suggested benefit.
While many more investigations will without a doubt be published on the topic, clinical judgment, patient and procedure-related characteristics, local preferences, and a multitude of other factors will have to continue to guide physicians’ choices of anesthetic and analgesic techniques in day-to-day practice. We agree, however, with Kooij et al.1 that designations of individual techniques and approaches as “standard of care” are of little value in the era of individualized health care and dynamic changes in scientific knowledge. E
Dr. Spencer Liu is the Section Editor for Pain Medicine for the Journal. This manuscript was handled by Dr. Terese T. Horlocker, Section Editor for Regional Anesthesia, and Dr. Liu was not involved in any way with the editorial process or decision.
Name: Stavros G. Memtsoudis, MD, PhD, FCCP.
Contribution: This author helped conceptualize and prepare the manuscript.
Attestation: Stavros G. Memtsoudis approved the final manuscript.
Name: Spencer S. Liu, MD.
Contribution: This author helped conceptualize and prepare the manuscript.
Attestation: Spencer S. Liu approved the final manuscript.
1. Kooij FO, Schlack WS, Preckel B, Hollmann MW. Does regional anesthesia for major surgery improve outcome? Focus on epidural analgesia. Anesth Analg. 2014;119:740–4
2. Rodgers A, Walker N, Schug S, McKee A, Kehlet H, van ZA, Sage D, Futter M, Saville G, Clark T, MacMahon S. Reduction of postoperative mortality and morbidity with epidural or spinal anaesthesia: results from overview of randomised trials. BMJ. 2000;321:1493
3. Guay J, Choi PT, Suresh S, Albert N, Kopp S, Pace NL. Neuraxial anesthesia for the prevention of postoperative mortality and major morbidity: an overview of Cochrane systematic reviews. Anesth Analg. 2014;119:716–25
4. Memtsoudis SG, Sun X, Chiu YL, Stundner O, Liu SS, Banerjee S, Mazumdar M, Sharrock NE. Perioperative comparative effectiveness of anesthetic technique in orthopedic patients. Anesthesiology. 2013;118:1046–58
5. Neuman MD, Silber JH, Elkassabany NM, Ludwig JM, Fleisher LA. Comparative effectiveness of regional versus general anesthesia for hip fracture surgery in adults. Anesthesiology. 2012;117:72–92
6. Liu J, Ma C, Elkassabany N, Fleisher LA, Neuman MD. Neuraxial anesthesia decreases postoperative systemic infection risk compared with general anesthesia in knee arthroplasty. Anesth Analg. 2013;117:1010–6
7. Pugely AJ, Martin CT, Gao Y, Mendoza-Lattes S, Callaghan JJ. Differences in short-term complications between spinal and general anesthesia for primary total knee arthroplasty. J Bone Joint Surg Am. 2013;95:193–9
8. Raw RM, Todd MM, Hindman BJ, Mueller R. The overpowered mega-study is a new class of study needing a new way of being reviewed. Anesthesiology. 2014;120:245–6