The effect of tolvaptan on renal excretion of electrolytes and urea nitrogen in patients undergoing coronary artery bypass surgery.
Adequate fluid management is an important component of patient care following cardiac surgery. Our aim in this study was to determine the benefits of tolvaptan, an oral selective vasopressin-2 receptor antagonist that causes electrolyte-free water diuresis, in postoperative fluid management. We prospectively examined the effect of tolvaptan on renal excretion of electrolytes and urea nitrogen in cardiac surgery patients.



Patients undergoing coronary artery bypass surgery were randomized to receive conventional loop diuretics (Group C, n = 30) or conventional loop diuretic therapy plus tolvaptan (Group T, n = 27). Fractional excretions of sodium (FENA), potassium (FEK) and urea nitrogen (FEUN) were measured in both groups during post-surgical hospitalization.



Urine output was greater with tolvaptan (Group T) than without it (Group C), and some patients in Group C required intravenous as well as oral loop diuretics. Serum sodium concentrations decreased after surgery in Group C, but were unchanged in Group T (postoperative day [POD] 3, 139.8 ± 3.5 vs. 142.3 ± 2.6 mEq/L, p = 0.006). However, postoperative FENA values in Group C did not decrease, and the values were similar in both groups. Serum potassium levels remained lower and FEK values remained higher than the preoperative values, but only in Group C (all p < 0.05). BUN increased postoperatively in both groups, but it remained higher than its preoperative value only in Group C (all p < 0.01). Group T showed an initial increase in BUN, which peaked and then returned to its preoperative value within a week. The FEUN increased postoperatively in both groups, but the change was more pronounced in Group T (POD7, 52.7 ± 9.3 vs. 58.2 ± 6.5 %, p = 0.025).



Renal excretion of sodium and potassium reflects the changes in serum concentration in patients treated with tolvaptan. Patients treated only with loop diuretics showed a continuous excretion of sodium and potassium that led to electrolyte imbalance, whereas the combination of loop diuretics and tolvaptan increased renal urea nitrogen elimination. Tolvaptan therefore appears to be an effective diuretic that minimally affects serum electrolytes while adequately promoting the elimination of urea nitrogen from the kidneys in patients undergoing coronary artery bypass surgery.



The present study is registered with the UMIN Clinical Trials Registry (ID: UMIN000011039 ).
Department of Cardiovascular Surgery, Heart Center, Juntendo University, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan. tokato@juntendo.ac.jp.
Tomoko S
TS
Kato
Department of Cardiovascular Surgery, Heart Center, Juntendo University, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Hiroshi
H
Nakamura
Department of Cardiovascular Surgery, Heart Center, Juntendo University, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Mai
M
Murata
Department of Cardiovascular Surgery, Heart Center, Juntendo University, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Kishio
K
Kuroda
Division of Nephrology, Department of Internal Medicine, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
Hitoshi
H
Suzuki
Department of Cardiovascular Surgery, Heart Center, Juntendo University, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Yasutaka
Y
Yokoyama
Department of Cardiovascular Surgery, Heart Center, Juntendo University, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Akie
A
Shimada
Department of Cardiovascular Surgery, Heart Center, Juntendo University, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Satoshi
S
Matsushita
Department of Cardiovascular Surgery, Heart Center, Juntendo University, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Taira
T
Yamamoto
Department of Cardiovascular Surgery, Heart Center, Juntendo University, 2-1-1, Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
Atsushi
A
Amano
D000368:Aged; D065092:Antidiuretic Hormone Receptor Antagonists / Q000008:administration & dosage; D001552:Benzazepines / Q000008:administration & dosage*; D001806:Blood Urea Nitrogen; D001026:Coronary Artery Bypass; D003324:Coronary Artery Disease / Q000097:blood / Q000601:surgery* / Q000652:urine; D004231:Diuresis / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004573:Electrolytes / Q000652:urine*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D065667:Renal Elimination / Q000187:drug effects*; D000077602:Tolvaptan
D065092:Antidiuretic Hormone Receptor Antagonists; D001552:Benzazepines; D004573:Electrolytes; D000077602:Tolvaptan
Coronary artery bypass surgery; Electrolyte; Renal excretion; Tolvaptan; Urea nitrogen