Authors: Shadi Gadalla, M.B.,Ch.B.et al
INTRODUCTION: Patients undergoing colorectal surgery may experience high rates of complications. In addition to superior analgesia, the purported benefits of perioperative thoracic epidural analgesia (TEA) include the reduction in the incidence of pulmonary morbidity, namely pneumonia and myocardial events. Historical series have estimated upwards of 10% of patients undergoing colorectal surgery may develop pneumonia but with the evolution in medical care it is likely the incidence now sits below 5%. The purpose of this study is to review the published literature and calculate the effect of TEA on cardio-pulmonary complications and mortality following colorectal surgery.
Methods: Institutional approval not required. The study protocol complied with PRISMA guidelines. A database literature search ((MEDLINE, EMBASE, Pubmed, and the Cochrane Central Register of Controlled Trials (CENTRAL)) was completed by a research librarian to identify prospective, randomized trials where TEA was compared with other forms of analgesia in patients undergoing colorectal surgery. There were no limitations on date or language of publication. Abstracts and full-text articles were reviewed for inclusion and data extracted independently by two authors (S.G and P.V). The outcomes assessed were the incidence of mortality, pneumonia events and composite cardiovascular (CV) outcome of myocardial infarction, troponin leak and arrhythmia. We also secondarily assessed the incidence of perioperative hypotension. The secondary outcome was incidence of post-operative hypotension. Results are presented as number (percentage) and relative risk (RR) with 95% confidence interval (CI). Heterogeneity was assessed through the I2 statistic. Data was stored in a Microsoft Excel Spreadsheet and meta-analysis conducted with MetaXL software (EpiGear International, Sunrise Beach, Australia). A two-tailed p-value of less-than 0.05 defined statistical significance.
Results: Forty-one studies enrolling 3151 patients met the inclusion criteria. There were 1600 patients in the TEA and 1551 patients in the control group, respectively. No differences were found between groups for patient age, sex or ASA status. The overall mortality rate was 1.7% (52/3151, reported by 41 studies). There was no difference in mortality between the group exposed to TEA and the control group (RR 1.25, 95% CI 0.73-2.11, p=0.90, I2 0%). Pneumonia was observed in 3.3% (102/3091, reported by 41 studies) of patients. There was again no difference between the TEA and control group (RR 0.87, 95% CI 0.60-1.26, p=0.85, I2 0%). In a sensitivity analysis, the removal of one large study with a high event rate did not alter the results for either outcome. The CV composite of myocardial infarction, troponin leakage and arrhythmia was observed in 16.5% (238/1441, reported by 9 studies). There was no difference in event rate between the two groups (RR 1.05, 95% CI 0.84-1.31, p=0.78, I2 0%). Perioperative hypotension was seen in 13.5% (102/758, reported by 14 studies) of patients. Use of TEA was associated with greater risk of hypotension compared with controls (RR 2.34, 95% CI 1.24-4.41, p=0.04, I2 44%).
Conclusions: In patients undergoing colorectal surgery there was no difference in mortality, pulmonary events or a composite of non-fatal cardiac outcomes between those who received TEA compared with alternative analgesia. These findings are contrary to other studies in patients undergoing either open aortic aneurysm repair or more generic abdominal surgery. TEA use was however associated with a higher risk of developing post-operative hypotension. These findings will be further explored through additional data collection and analyses to help refine the role of TEA in modern colorectal anesthesia.