ENDOGENOUS NITRIC-OXIDE AND LOW SYSTEMIC VASCULAR-RESISTANCE AFTER CARDIOPULMONARY BYPASS

Objectives: To investigate the relationship between excessive endogeno us production of nitric oxide (NO) and the low systemic vascular resis tance (SVR) syndrome after cardiac surgery. Design: Prospective, case- control. Cases defined by low SVR postoperatively (< 750 dyn/s/cm(-5)) , and matched with controls (> 900 dyn/s/cm(-5)). Setting: Cardiothora cic intensive care unit (ICU) in a tertiary care hospital.Participants : Forty-four patients after cardiac surgery. Interventions: Collection of plasma and urine samples after identification. Measurements and Ma in Results: Plasma and urine nitrate concentrations were measured as a n index of endogenous NO production. Hemodynamic, inotropic, arid outc ome data were collected. Median nitrate concentrations did not differ between cases and controls (plasma, 58 mu mol/L v62 mu mol/L, p = 0.43 ; urine, 399 mu mol/L v404 mu mol/L, p = 0.38). Times to extubation an d intensive care unit (ICU) discharge were prolonged in patients with low SVR (17.8 hours v8.7 hours, p = 0.021; 2.5 days v1.2 days, p = 0.0 19, respectively). Conclusions:No association between ''low SVR syndro me'' and endogenous NO production was found. Patients with low SVR aft er cardiac surgery required a longer period of inotropic and ventilato r support, with delay in discharge from the ICU. The risk and cost imp lications of this syndrome support further research. Copyright (C) 199 7 by W.B. Saunders Company.