Role of intraoperative oliguria in risk stratification for postoperative acute kidney injury in patients undergoing colorectal surgery with an enhanced recovery protocol: A propensity score matching analysis

Background
The enhanced recovery after surgery (ERAS) protocol for colorectal cancer resection recommends balanced perioperative fluid therapy. According to recent guidelines, zero-balance fluid therapy is recommended in low-risk patients, and immediate correction of low urine output during surgery is discouraged. However, several reports have indicated an association of intraoperative oliguria with postoperative acute kidney injury (AKI). We investigated the impact of intraoperative oliguria in the colorectal ERAS setting on the incidence of postoperative AKI.
Patients and methods
From January 2017 to August 2019, a total of 453 patients underwent laparoscopic colorectal cancer resection with the ERAS protocol. Among them, 125 patients met the criteria for oliguria and were propensity score (PS) matched to 328 patients without intraoperative oliguria. After PS matching had been performed, 125 patients from each group were selected and the incidences of AKI were compared between the two groups. Postoperative kidney function and surgical outcomes were also evaluated.
Results
The incidence of AKI was significantly higher in the intraoperative oliguria group than in the non-intraoperative oliguria group (26.4% vs. 11.2%, respectively, P = 0.002). Also, the eGFR reduction on postoperative day 0 was significantly greater in the intraoperative oliguria than non-intraoperative oliguria group (−9.02 vs. −1.24 mL/min/1.73 m2 respectively, P < 0.001). In addition, the surgical complication rate was higher in the intraoperative oliguria group than in the non-intraoperative oliguria group (18.4% vs. 9.6%, respectively, P = 0.045).
Conclusions
Despite the proven benefits of perioperative care with the ERAS protocol, caution is required in patients with intraoperative oliguria to prevent postoperative AKI. Further studies regarding appropriate management of intraoperative oliguria in association with long-term prognosis are needed in the colorectal ERAS setting.

研究背景
结直肠癌切除术加速康复外科（Enhanced Recovery After Surgery, ERAS）方案推荐采用平衡的围术期液体治疗策略。根据最新临床指南，低危患者需实施零平衡液体治疗，且不建议术中即刻纠正低尿量状态。然而多项研究表明，术中少尿与术后急性肾损伤（Acute Kidney Injury, AKI）存在显著关联。本研究旨在探讨结直肠癌加速康复外科情境下的术中少尿对术后急性肾损伤发生率的影响。

患者与方法
2017年1月至2019年8月期间，共计453例患者接受了符合加速康复外科方案的腹腔镜结直肠癌切除术。其中125例符合术中少尿诊断标准的患者，通过倾向评分（Propensity Score, PS）匹配法与328例无术中少尿的患者进行配对。倾向评分匹配完成后，两组各选取125例患者，对比术后急性肾损伤的发生率，并评估两组术后肾功能与手术结局。

研究结果
术中少尿组患者的术后急性肾损伤发生率显著高于非术中少尿组（分别为26.4%与11.2%，P=0.002）。此外，术后即刻（术后0日）的估算肾小球滤过率（estimated Glomerular Filtration Rate, eGFR）下降幅度，术中少尿组亦显著大于非术中少尿组（分别为-9.02与-1.24 mL/min/1.73m²，P<0.001）。另外，术中少尿组的手术并发症发生率亦高于非术中少尿组（分别为18.4%与9.6%，P=0.045）。

研究结论
尽管加速康复外科方案的围术期护理已被证实具有临床获益，但对于术中少尿患者仍需加强临床警惕，以预防术后急性肾损伤的发生。在结直肠癌加速康复外科情境下，仍需开展进一步研究，以探讨术中少尿的合理管理方案及其与长期预后的关联。