Literature Review
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Reduction of postoperative mortality and
morbidity with epidural or spinal anaesthesia: results from overview of
randomized trials.
Objectives To obtain reliable estimates of the effects of neuraxial blockade with epidural or spinal anaesthesia on postoperative morbidity and mortality.
Design Systematic review of all trials with randomization to intraoperative neuraxial blockade. 141 trials including 9559 patients for which data were available before 1 January 1997. Trials were eligible irrespective of their primary aims, concomitant use of general anaesthesia, publication status, or language. Trials were identified by extensive search methods, and substantial amounts of data were obtained or confirmed by correspondence with trialists.
Results Overall mortality was reduced by about a third in patients allocated to neuraxial blockade (103 deaths/4871 patients versus 144/4688 patients, odds ratio = 0.70, 95% confidence interval 0.54 to 0.90, p=0.006). Neuraxial blockade reduced the odds of deep venous thrombosis by 44%, pulmonary embolism by 55%, transfusion requirements by 50%, pneumonia by 39%, and respiratory depression by 59% (all P<0.001). There were also reductions in myocardial infarction and renal failure. Although there was limited power to assess subgroup effects, the proportional reductions in mortality did not clearly differ by surgical group, type of blockade (epidural or spinal), or in those trials in which neuraxial blockade was combined with general anaesthesia compared with trials in which neuraxial blockade was used alone. Conclusions Neuraxial blockade reduces postoperative mortality and other serious complications. The size of some of these benefits remain uncertain, and further research is required to determine whether these effects are due solely to benefits of neuraxial blockade or partly to avoidance of general anaesthesia. Nevertheless, these findings support more widespread use of neuraxial blockade. |
Discussion There are two types of reviews to be found in the anesthesia literature, narrative and systematic. A narrative review is an overview of a particular topic with recommendations from clinical experts. This study is an example of a systematic review, which is a study that uses scientific strategies to reduce bias in the collection, appraisal and interpretation of relevant studies. Systematic reviews are fairly new in the anesthesia literature, and can be used to summarize existing information, provide estimates of the effects of established interventions or provide supporting evidence for practice guidelines. Systematic reviews are generally described as systematic reviews, systematic overviews, quantitative reviews or meta-analysis. When evaluating a systematic review it is important that the authors report the following information: the search method should be comprehensive and well-described, the criteria for deciding which studies will be included should be discussed, selection bias should be avoided, criteria for assessing the validity of the included studies should be reported as should the method for combining the studies, the findings of the combined studies should be relevant to the proposed question (in this case—does regional anesthesia decrease operative mortality and morbidity) and finally the conclusions should be supported by the data. The methods in this review are well described and thorough. 141 studies in which patients were randomized to intraoperative neuraxial block (both spinals and epidurals, with or without general anesthesia) were identified through four different databases. Two unblinded reviewers independently recorded the published findings from each study. A third reviewer then reviewed the analysis. Statistical analysis was odds ratios, 95% confidence intervals, and two sided P values for each outcome using Peto's modification of Mantel-Haenszel method. Previous randomized clinical trials focusing on fatal or life-threatening events associated with regional or general anesthesia have been too small to detect effects of significant size reliably. Thus the findings of this study are fascinating. The authors conclude that overall mortality was reduced by a third in patients randomized to neuraxial block (p=0.0006). Neuraxial blockade reduced the odds of DVT by 44%, PE by 55%, transfusion requirements by 50%, pneumonia by 39% and respiratory depression by 59% (p=<0.001 for all). These findings seem to substantiate the author's conclusions that encourage a more widespread use of neuraxial blockade. Julia E. Pollock, MD |
