Early introduction of tolvaptan after cardiac surgery: a renal sparing strategy in the light of the renal resistive index measured by ultrasound

BACKGROUND Renal failure is a serious complication after cardiac surgery, which can be caused by long-term intravenous (IV) loop diuretic use. Tolvaptan is an oral selective vasopressin-2 receptor antagonist used in patients irresponsive to loop diuretics. We investigated their renal perfusion changes using the resistive index (RI) postoperatively. METHODS Serial renal RI, echocardiography, and laboratory examinations from 14 patients requiring continuous postoperative IV loop diuretics were reviewed. Eight patients received tolvaptan (Group T) and six received oral loop diuretics before the discontinuation of IV loop diuretics (Group L). The 1(st) data were obtained between postoperative day 0 and 2, the 2(nd) when patients were still under IV loop diuretic treatment, the 3(rd) after the initiation of tolvaptan or oral loop diuretic, and the 4(th) after the discontinuation of IV diuretics. RESULTS The 2(nd) RI value was higher in Group T than Group L (0.77 ± 0.09 vs. 0.69 ± 0.01, p = 0.049) but significantly decreased after tolvaptan administration [0.77 ± 0.09 to 0.65 ± 0.05 (2(nd) to 3(rd)), to 0.62 ± 0.04 (to 4(th)), both p = 0.006], while no such changes were seen in Group L. The serum sodium and albumin levels, and echo-derived tricuspid annular plane systolic excursion increased only in Group T (134.1 ± 1.5 to 138.8 ± 3.2 mEq/L, 3.3 ± 0.3 to 3.7 ± 0.5 g/dL, 16.4 ± 3.6 to 19.7 ± 4.2 mm, all p <0.05). The duration of IV loop diuretics tended to be shorter in Group T than Group L (5.6 ± 1.6 vs. 8.7 ± 3.6 days, p = 0.051). CONCLUSIONS Administration of tolvaptan in patients undergoing cardiac surgery may improve their renal perfusion, as reflected by the renal RI measured using renal Doppler ultrasound.