Tolvaptan, a vasopressin type-2 receptor antagonist, is utilized to ameliorate fluid retention following cardiac surgery. However, the optimal timing of tolvaptan administration considering novel biomarkers remains unknown. We prospectively included patients who underwent cardiac surgery between 2016 and 2020. We measured perioperative trends of free water reabsorption mediators including plasma arginine vasopressin and urine aquaporin-2. A total of 20 patients (68 [60, 75] years old, 18 men) were included. Urine volume decreased gradually after the initial 3 hours following cardiac surgery. The plasma arginine vasopressin level increased significantly with a peak at postoperative 6 hours, whereas the urine aquaporin-2 level increased later with a delayed peak at postoperative 12 hours. As a result, urine aquaporin-2 relative to the plasma arginine vasopressin level, which represents the activity of the collecting ducts and indicates predicted responses to tolvaptan, was a minimum at postoperative 6 hours. Tolvaptan administration immediately after cardiac surgery might not be recommended given the transient refractoriness to tolvaptan probably due to the stunning of kidney collecting ducts.

托伐普坦是一种血管加压素 2 型受体拮抗剂，用于改善心脏手术后的液体潴留。然而，考虑到新型生物标志物，托伐普坦给药的最佳时机仍然未知。我们前瞻性地纳入了 2016 年至 2020 年间接受心脏手术的患者。我们测量了游离水重吸收介质的围手术期趋势，包括血浆精氨酸加压素和尿水通道蛋白 2。共纳入 20 名患者（68 [60, 75] 岁，18 名男性）。心脏手术后最​​初 3 小时后，尿量逐渐减少。血浆精氨酸加压素水平显着升高，在术后 6 小时达到峰值，而尿水通道蛋白 2 水平升高较晚，在术后 12 小时出现延迟峰值。其结果，尿水通道蛋白 2 相对于血浆精氨酸加压素水平（代表集合管的活动并指示对托伐普坦的预测反应）在术后 6 小时时最低。可能不推荐心脏手术后立即使用托伐普坦，因为托伐普坦可能是由于肾集合管致昏导致的暂时性难治性。