Review Effect of thoracic epidural anaesthesia on splanchnic blood flow E. R. Richards, S. I. Kabir, C.-E. McNaught and J. MacFie Joint Gastroenterology Research Unit, Scarborough General Hospital, Woodlands Drive, Scarborough YO12 6QL, UK Correspondence to: Miss C.-E. McNaught (e-mail: mcnaught@aol.com) Background: Thoracic epidural anaesthesia (TEA) is used widely in colorectal surgery. However, there is increasing concern that epidurals are associated with postoperative hypotension, mediating a potential reduction in splanchnic flow. The aim was to review the literature on the effects of TEA on splanchnic blood flow. Methods: PubMed and Cochrane databases were searched. Search terms used were: English language, ‘thoracic epidural splanchnic flow’, ‘thoracic epidural gut blood flow’, ‘thoracic epidural intestinal blood flow’ and ‘thoracic epidural colonic blood flow’. Abstracts were reviewed by two independent researchers and irrelevant studies excluded. The full text of the remaining articles was then retrieved. Results: Twenty-two abstracts were reviewed and three excluded. Nineteen papers were reviewed in full and seven irrelevant articles excluded. Five human studies investigated the effects of TEA on splanchnic flow. Two studies measured splanchnic flow directly and found an epidural-mediated fall in flow, unresponsive to intravenous fluids and requiring vasopressors or inotropes to restore baseline flow. The remaining three studies had inconsistent findings and haemodynamic stability was maintained. The seven animal studies identified were heterogeneous in both methodology and findings. Three suggested a protective role for thoracic epidurals in septic shock and pancreatitis. Conclusion: These findings are inconsistent; however, the two studies that investigated the effects of vasoconstrictors on splanchnic blood flow directly both found a significant epidural-mediated reduction in splanchnic blood flow that was unresponsive to fluid therapy. Presented to a congress of the Association of Surgeons of Great Britain and Ireland, Liverpool, UK, May 2012; published in abstract form as Br J Surg 2012; 99(Suppl 6): 2 Paper accepted 27 September 2012 Published online 30 November 2012 in Wiley Online Library (www.bjs.co.uk). DOI: 10.1002/bjs.8993 Introduction It is now generally accepted that epidural blockade is effec- tive in reducing postoperative pain in patients undergoing major abdominal surgery. In addition, epidurals may be associated with improved postoperative respiratory func- tion and attenuation of the neuroendocrine stress response to surgery. Not surprisingly, therefore, the use of epidural anaesthesia has become standard practice in many colo- rectal units as well as being adopted as an important part of enhanced recovery plans. There is increasing concern that the use of epidural anaesthesia is associated with postoperative hypotension and a reduction in splanchnic blood flow. This, it has been suggested, might affect anastomotic perfusion, although any effects on subsequent anastomotic leakage remain unproven 1 . Indeed, one animal study demonstrated an increase in anastomotic bursting pressures with epidural analgesia 2 . The splanchnic blood supply is provided by coeliac and mesenteric arteries that anastomose extensively to provide a vast collateral supply to the foregut, midgut and hindgut. Splanchnic blood flow is determined by many intrinsic and extrinsic mechanisms including cardiac function, the auto- nomic nervous system and neuroendocrine mediators. In experimental studies epidural blockade of the sympathetic outflow from segments T1 to L1 results in splanchnic and peripheral vasodilatation and functional hypovolaemia. It is unclear, however, what the situation is in patients under- going abdominal surgery. The aim of this review was an attempt to resolve this question. Methods PubMed and Cochrane databases were searched using the following terms: English language, ‘thoracic epidural splanchnic flow’, ‘thoracic epidural gut blood flow’, ‘thoracic epidural intestinal blood flow’ and ‘thoracic  2012 British Journal of Surgery Society Ltd British Journal of Surgery 2013; 100: 316–321 Published by John Wiley & Sons Ltd Downloaded from https://academic.oup.com/bjs/article/100/3/316/6138272 by guest on 10 June 2022