An increase in urinary nitrite/nitrate excretion is associated with the hyperdynamic state after cardiovascular surgery

Byline: Chieko Mitaka (1), Kuninori Yokoyama (2), Takashi Morimoto (1), Toshihisa Nosaka (1), Makoto Sunamori (3), Takasuke Imai (1) Keywords: Cardiac output Cardiovascular surgery Nitric oxide Systemic inflammatory response syndrome (SIRS) Systemic vascular resistance Vasoactive drugs Abstract: Abstract Objectives . To test the hypotheses (1) that nitric oxide (NO) production is stimulated after cardiovascular surgery and is related to the hyperdynamic state and (2) that NO production is more prominent in patients with cardiopulmonary bypass. Design: Prospective, clinical study. Setting: Intensive care unit in a university hospital. Patients: One hundred patients after cardiovascular surgery: coronary artery bypass graft with (n=53) and without (n=17) cardiopulmonary bypass, valve surgery with cardiopulmonary bypass (n=23) and thoracic aortic replacement with cardiopulmonary bypass (n=7). Interventions: None. Measurements and results: Urinary nitrite/nitrate (NOx) excretion was measured by the high-performance liquid chromatography-Griess system as an index of endogenous NO production during the first 2 postoperative days. Hemodynamic variables, hematologic variables and serum C-reactive protein concentrations were measured after the operation. Urinary NOx concentrations were 146+/--70 and 190+/--93 Aumol/l, and the amounts of NOx excreted in the urine were 23+/--10 and 18+/--8 Aumol/h on the 1st and 2nd days, respectively. Urinary NOx excretions were positively correlated with the cardiac index (P Conclusion: These findings suggest, firstly, that NO production is stimulated by a surgical inflammatory response and, secondly, that the endogenous NO contributes to the increase in cardiac output that accompanies the reduced systemic vascular resistance after cardiovascular surgery. Author Affiliation: (1) Department of Critical Care Medicine, Tokyo Medical and Dental University Graduate School, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8519, Japan (2) Department of Anesthesiology, Tokyo Medical and Dental University Graduate School, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8519, Japan (3) Department of Thoracic and Cardiovascular Surgery, Tokyo Medical and Dental University Graduate School, 1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8519, Japan Article History: Received Date: 13/07/2001 Accepted Date: 31/05/2002 Article note: Electronic Publication