S150 Nitroprusside (NP) is used to assess the reversibility of pulmonary hypertension during assessment for orthotropic heart transplantation, as well as, therapy to reduce pulmonary vascular resistance (PVR), in the postoperative heart transplant patient. Its use, however, is limited due to hypotension and deleterious effects on gas exchange. Nitric oxide (NO) reduces PVR, has no effect on systemic blood pressure (BP) and may improve gas exchange. Thus, the following preliminary results compare the effects of NP and NO on gas exchange in four potential heart transplant candidates. METHODS: Mean BP was measured continuously using a radial arterial line. Baseline (FIO2=21) arterial/venous (via pulmonary artery catheter) gases were drawn to calculate Qs/Qt. NO (40 ppm; FIO2=.23) was then administered via a spontaneous breathing circuit and arterial/venous gases were repeated. Baseline gases were repeated 20 minutes after discontinuation of NO. NP infusion was titrated to a maximum dose as tolerated by the patient and the gases were repeated. Paired Student's t-tests compared baseline vs therapy (NO and NP) for Qs/Qt and mean BP. RESULTS: The maximum mean NP dose achieved was 1.75 +/-.96 [micro sign]g/min. NP infusion significantly increased Qs/Qt (P =.0219) and decreased mean BP (P =.0377) while NO had no effect on these variables (Table 1).Table 1CONCLUSIONS: NO is the preferred agent to treat pulmonary hypertension post orthotropic heart transplantation as it has no effect on BP and may improve oxygenation at a time when systemic hypotension, hypoxemia and right ventricular dysfunction are commonplace. Grant: University Campus Pooled Research Trust Fund
