BACKGROUND Acute kidney injury (AKI) is a common complication of cardiac surgery. An intraoperative monitor of kidney perfusion is needed to identify patients at risk for AKI. The authors created a noninvasive urinary oximeter that provides continuous measurements of urinary oxygen partial pressure and instantaneous urine flow. They hypothesized that intraoperative urinary oxygen partial pressure measurements are feasible with this prototype device and that low urinary oxygen partial pressure during cardiac surgery is associated with the subsequent development of AKI. METHODS This was a prospective observational pilot study. Continuous urinary oxygen partial pressure and instantaneous urine flow were measured in 91 patients undergoing cardiac surgery using a novel device placed between the urinary catheter and collecting bag. Data were collected throughout the surgery and for 24 h postoperatively. Clinicians were blinded to the intraoperative urinary oxygen partial pressure and instantaneous flow data. Patients were then followed postoperatively, and the incidence of AKI was compared to urinary oxygen partial pressure measurements. RESULTS Intraoperative urinary oxygen partial pressure measurements were feasible in 86/91 (95%) of patients. When urinary oxygen partial pressure data were filtered for valid urine flows greater than 0.5 ml · kg-1 · h-1, then 70/86 (81%) and 77/86 (90%) of patients in the cardiopulmonary bypass (CPB) and post-CPB periods, respectively, were included in the analysis. Mean urinary oxygen partial pressure in the post-CPB period was significantly lower in patients who subsequently developed AKI than in those who did not (mean difference, 6 mmHg; 95% CI, 0 to 11; P = 0.038). In a multivariable analysis, mean urinary oxygen partial pressure during the post-CPB period remained an independent risk factor for AKI (relative risk, 0.82; 95% CI, 0.71 to 0.95; P = 0.009 for every 10-mmHg increase in mean urinary oxygen partial pressure). CONCLUSIONS Low urinary oxygen partial pressures after CPB may be associated with the subsequent development of AKI after cardiac surgery. EDITOR’S PERSPECTIVE

中文翻译：

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无创尿氧监测和心脏手术中急性肾损伤的风险。

背景急性肾损伤（AKI）是心脏手术的常见并发症。需要对肾灌注进行术中监测，以识别有 AKI 风险的患者。作者创建了一种无创尿氧计，可连续测量尿氧分压和瞬时尿流量。他们假设使用这种原型装置测量术中尿氧分压是可行的，并且心脏手术期间的低尿氧分压与随后的 AKI 发展有关。方法 这是一项前瞻性观察性试验研究。使用放置在导尿管和收集袋之间的新型装置测量了 91 名接受心脏手术的患者的连续尿氧分压和瞬时尿流量。在整个手术过程和术后 24 小时收集数据。临床医生对术中尿氧分压和瞬时流量数据不知情。然后对患者进行术后随访，并将 AKI 的发生率与尿氧分压测量值进行比较。结果 术中尿氧分压测量在 86/91 (95%) 的患者中是可行的。当有效尿流量大于 0.5 ml·kg-1·h-1 过滤尿氧分压数据时，70/86 (81%) 和 77/86 (90%) 的患者在体外循环 (CPB)和 CPB 后时期分别被包括在分析中。随后发生 AKI 的患者在 CPB 后期间的平均尿氧分压显着低于未发生 AKI 的患者（平均差，6毫米汞柱；95% CI，0 至 11；P = 0.038）。在一项多变量分析中，CPB 后期间的平均尿氧分压仍然是 AKI 的独立危险因素（相对风险，0.82；95% CI，0.71 至 0.95；平均尿氧每增加 10 mmHg，P = 0.009分压）。结论 CPB 后尿氧分压低可能与心脏手术后 AKI 的后续发展有关。编辑观点 结论 CPB 后尿氧分压低可能与心脏手术后 AKI 的后续发展有关。编辑观点 结论 CPB 后尿氧分压低可能与心脏手术后 AKI 的后续发展有关。编辑观点