Boodhwani Munir, Rubens Fraser D, Wozny Denise, Nathan Howard J
Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
Ann Thorac Surg. 2009 Feb;87(2):489-95. doi: 10.1016/j.athoracsur.2008.10.078.
Hypothermia is a potential strategy for visceral organ protection during cardiopulmonary bypass (CPB). We report data from two randomized studies evaluating mild hypothermia and rewarming on postoperative renal function in cardiac surgical patients.
Patients undergoing nonemergency, isolated coronary artery bypass grafting were enrolled into two studies. In the first, 223 patients were cooled to 32 degrees C during CPB and randomly assigned to rewarming to 37 degrees C (RW-37 degrees) or 34 degrees C (RW-34 degrees). The second study randomized 267 patients to sustained mild hypothermia at 34 degrees C (S-34 degrees) or normothermia (S-37 degrees) without rewarming. Serum creatinine levels were measured. Creatinine clearance was calculated. Significant renal dysfunction was defined as a 25% increase in serum creatinine or a 25% decrease in creatinine clearance postoperatively.
Postoperative serum creatinine levels were persistently higher in the RW-37 degrees patients than in the RW-34 degrees group (p < 0.01). RW-37 degrees patients had a higher incidence of renal dysfunction (17%) than RW-34 degrees patients (9%, p = 0.07). Sustained mild hypothermia had no beneficial effect on postoperative serum creatinine levels (p = 0.44) or significant renal dysfunction: S-34 degrees, 20% vs S-37 degrees, 15% (p = 0.28). Diabetes (odds ratio [OR], 1.6; 95% confidence interval [CI] 1.3 to 2.1), prolonged CPB time (OR, 1.1; 95% CI, 1.0 to 1.2), and rewarming (OR, 1.4; 95% CI, 1.0 to 1.9) were independent risk factors for significant renal dysfunction. Renal dysfunction was associated with longer hospital stay (8.4 +/- 0.8 vs 6.8 +/- 04 days, p < 0.001).
Sustained mild hypothermia does not improve renal outcome. However, rewarming on CPB is associated with increased renal injury and should be avoided.
低温是体外循环（CPB）期间保护内脏器官的一种潜在策略。我们报告了两项随机研究的数据，评估轻度低温及复温对心脏手术患者术后肾功能的影响。
接受非急诊单纯冠状动脉搭桥术的患者被纳入两项研究。在第一项研究中，223例患者在CPB期间被冷却至32℃，并随机分配至复温至37℃（RW-37℃组）或34℃（RW-34℃组）。第二项研究将267例患者随机分为持续轻度低温34℃（S-34℃组）或常温（S-37℃组）且不复温。测量血清肌酐水平，计算肌酐清除率。严重肾功能不全定义为术后血清肌酐升高25%或肌酐清除率降低25%。
RW-37℃组患者术后血清肌酐水平持续高于RW-34℃组（p<0.01）。RW-37℃组患者肾功能不全发生率（17%）高于RW-34℃组患者（9%，p=0.07）。持续轻度低温对术后血清肌酐水平（p=0.44）或严重肾功能不全无有益影响：S-34℃组为20%，S-37℃组为15%（p=0.28）。糖尿病（比值比[OR]，1.6；95%置信区间[CI]1.3至2.1）、CPB时间延长（OR，1.1；95%CI，1.0至1.2）及复温（OR，1.4；95%CI，1.0至1.9）是严重肾功能不全的独立危险因素。肾功能不全与住院时间延长相关（8.4±0.8天对6.8±0.4天，p<0.001）。
持续轻度低温并不能改善肾脏预后。然而，CPB期间复温与肾损伤增加相关，应避免。
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