NIFEDIPINE CAN PRESERVE RENAL-FUNCTION IN PATIENTS UNDERGOING AORTIC-SURGERY WITH INFRARENAL CROSS-CLAMPING

Sixteen patients diagnosed with an aneurysm of abdominal aorta or Leri che disease underwent elective aortic surgery involving crossclamping of infrarenal aorta (ICC). These patients were randomized into two equ al groups and 8 patients were infused with nifedipine starting from th e isolation of aorta until the end of surgery (group A) while another 8 patients were infused with low-dose dopamine (group B) over the same surgical course. Plasma endothelin (ET) was measured before the induc tion of anesthesia, at the beginning and at the end of the clamp perio d and at the end of the operation. Intraoperatively, creatinine cleara nce and urinary excretion of PGE(2), 6-keto PGF(1 alpha) and TxB(2) we re also determined before, during and after aortic crossclamping. Preo perative GFR as well as preinduction cardiac index (CI) and pulmonary capillary wedge pressure (PCWP) of the two groups did not differ. Duri ng crossclamping plasma ET rose significantly in both groups. However, after clamp removal, plasma ET decreased in group A while it remained elevated in group B. Urinary excretion of TxB(2), PGE(2) and 6-keto P GF(1 alpha) increased during clamp in both groups, but the ratio of PG E(2) + 6-keto PGF(1 alpha)/TxB(2) during and after clamp was significa ntly higher in group A than in B. Postclamp creatinine clearance decre ased in group B, and increased in group A; postoperative value of GFR was unchanged in group A and decreased significantly in group B. In co nclusion, infusion of nifedipine, in contrast to dopamine, prevented t he decrease of GFR in patients undergoing aortic surgery. This effect could be mediated by a nifedipine modulation of ET vascular synthesis and/or a preferential renal synthesis of vasodilating prostanoids.