From the data available from large, randomised clinical trials, meta-analyses, and systematic reviews on the effect of continuous postoperative epidural analgesia on surgical outcome, the overall effects on morbidity, hospital stay, and convalescence have been limited, except for a reduction in pulmonary morbidity and ileus.1-3,5-8,12,15 By contrast, comparative studies in lower body procedures have suggested a positive effect on allover morbidity and mortality by the provision of intraoperative regional blocks versus general anaesthesia.4
A continuous epidural analgesia including local anaesthetics has been shown convincingly to have several advantageous physiological effects, including efficient dynamic pain relief,9 improvement of protein economy,10,11 reduction in ileus3,12,16 as well as improvement in postoperative pulmonary function,11 and decrease in cardiac demands.11 It is, therefore, surprising that these effects have not translated into a more clear-cut demonstration of improved outcome in major operations. There may be two explanations for the discrepancy between the physiological data and the clinical morbidity outcome effects. It may be that continuous postoperative epidural analgesia has no beneficial effect on postoperative morbidity (except for pulmonary outcome and ileus), or the potential advantageous clinical effects have been obscured by factors in perioperative care management that do not take full advantage of the physiological effects of epidural analgesia.
As a working hypothesis, the second explanation may be more constructive and is probably correct. Thus, several recent studies have clearly shown that postoperative outcome is determined by multiple factors involved in perioperative care13,18-20 including patient information, stress reduction, pain relief, mobilisation, and early nutrition.21 Several of these factors are positively achieved or supported by a continuous postoperative epidural regimen, but it is noticeable that the hitherto available randomised studies have not included such a revision of the perioperative care programme towards enforced early multimodal rehabilitation.13 Thus, it may be thought-provoking that studies with a revision of the perioperative programme have decreased hospital stay to about three days after elective aortic surgery without using epidural analgesia,22 which is significantly less than the 7-10 days reported in the randomised studies on epidural analgesia.5 These results clearly indicate that factors other than epidural analgesia must be controlled and included in future trials of epidural analgesia and outcome. Similar findings have been observed with fast-track pulmonary resections, with postoperative hospital stays of between one and five days,23,24 and in elderly high-risk patients undergoing colonic surgery, where a multimodal rehabilitation programme including continuous thoracic epidural analgesia decreased hospital stay to two to three days.18 In later studies, the advantages of a multimodal rehabilitation regimen on pulmonary function, nocturnal hypoxaemia, exercise capacity, and preservation of lean body mass were documented.25 In a recent small-scale (n = 64) randomised study comparing continuous thoracic epidural analgesia with patient-controlled analgesia in patients undergoing colonic surgery,16 advantageous effects of epidural analgesia on pain and ileus were again confirmed. In addition, reduced fatigue, increased mobilisation and exercise capacity (six-minute walking test), as well as increased quality of life (SF-36), were found three to six weeks postoperatively. It must be emphasised that this trial is so far the best randomised trial, as it included revised perioperative care principles adjusted to recent scientific data13 with no routine use of nasogastric tubes, early oral feeding, and mobilisation to facilitate the well known positive physiological effects of epidural analgesia on outcome.5 Finally, a fast-track multimodal rehabilitation programme including epidural analgesia decreased hospital stay after open abdominal hysterectomy to about two days,26 which again is less than reported previously in randomised trials comparing epidural with general anaesthesia for this operation.5
These observations, mostly from exploratory non-randomised trials, show that postoperative outcome is determined by multiple factors. They suggest, therefore, that previous randomised trials on epidural anaesthesia and postoperative outcome have a suboptimal design as they did not include a revised perioperative care regimen that aims to enhance recovery through the beneficial physiological effects of epidural analgesia. In addition to factors such as patient information, stress reduction, optimised pain relief, and enforced mobilisation and oral nutrition,21 several other factors have to be considered and included in future randomised trials on epidural analgesia and outcome. Thus, careful attention to the provided fluid regimen is important, as fluid excess may increase the risk of postoperative morbidity.27 This may be particularly relevant in major abdominal procedures, as fluid excess may also prolong postoperative ileus.28 Again, randomised clinical trials have often included the administration of large volumes of fluid27 or not mentioned fluid administration, thereby precluding sufficient interpretation of data.
In summary, the evolving concept of fast-track surgery and multimodal postoperative rehabilitation programmes13 with demonstrated improved outcomes and reduction of postoperative hospital stay indicates that previous efforts to show an improvement in postoperative outcome after major operations by continuous epidural analgesia may have had a faulty design, thereby precluding sufficient interpretation and assessment of the topic. Hopefully, future randomised trials will include a revised multimodal programme aiming to enhance recovery, and thereby providing a rational basis to answer whether continuous epidural postoperative analgesia will or will not improve postoperative outcome following major operations. Consequently, further analyses of clinical studies may not be meaningful, as they are unlikely to provide valid answers to the topic.
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