IOURNAL OF SURGICAL RESEARCH 32, 243-248 (1982) Pharmacologic Alterations in Pulmonary Artery Pressure in the Adult Respiratory Distress Syndrome JOHN A. WEIGELT, M.D., *J BRUCE L. GEWERTZ, M.D.,j-*2 CHRISTINA M. AURBAKKEN, R. N.,* AND WILLIAM H. SNYDER, III, M.D., FACS* *Department of Surgery, Southwestern Medical School, The University of Texas Health Science Center, Dallas, Texas 75235, and tDepartment of Surgery, University of Chicago, Pritzker School of Medicine. Chicago, Illinois 60637 Presented at the Annual Meeting of the Association for Academic Surgery, Chicago, Illinois, November 8- 11, 198 1. The progressive hypoxemia of acute respiratory distress syndrome (ARDS) has been associated with increased pulmonary vascular resistance (PVR). Pharmacologic reduction of PVR might improve oxygenation in ARDS patients. To test this hypothesis we administered vasoactive drugs to nine hypoxemic patients (PaOF < 70 Torr) with increased PVR. Nitroprusside (1-3 pg/kg/min) or glu- cagon (0.5 mg/min) was administered iv for 15 min. Hemodynamic measurements were obtained before and during each infusion. Thirty-minute stabilization periods were allowed between infusions. Nitroprusside significantly decreased PVR, I75 to 139 dyn * set/cm’, (P c 0.05), yet intrapulmonary shunt (QJQ,) increased, 34 to 42% (P c 0.05) and arterial PO, decreased, 68 to 55 Torr (P < 0.01). 0, delivery, 615 to 519 ml/min/m’, was also significantly decreased (P < 0.05). Glucagon signifi- cantly increased arterial PO*, 67 to 73 Torr (P < 0.05), with little change in QJQl (36.4 to 33.8%). Glucagon also increased PVR (145 to 157 dyn * set/cm’). Nitroprusside-induced vasodilation is non- selective and supercedes protective hypoxic vasoconstriction. Glucagon improves oxygenation, but does not reduce PVR. Neither drug offers the palient with ARDS and pulmonary hypertension any specific benefits. The decrease in 02 delivery with nitroprusside further indicates that this drug should be used with caution in any hypoxic patient. INTRODUCTION The adult respiratory distress syndrome (ARDS) has a distressingly high mortality rate despite aggressive management. This poor prognosis is most evident in patients with increased mean pulmonary artery pres- sure and pulmonary vascular resistance. Za- pol and Snider studied 30 patients with ARDS and correlated survival with pro- gressive decreases in pulmonary vascular re- sistance [ 181. These data prompted our investigation to determine whether pharma- cologic reduction of increased pulmonary vascular resistance might improve arterial ’ To whom requests for reprints should be addressed: Department of Surgery, University of Texas Health Science Center, 5323 Harry Hines Blvd., Dallas, Tex. 75235. ’ Teaching Scholar of the American Heart Associa- tion. oxygenation and survival. Glucagon and nitroprusside were studied because they can effect pulmonary vascular resistance. [4, 121. MATERIALS AND METHODS Nine patients were treated in the surgical intensive care unit at Parkland Memorial Hospital, Dallas, Texas. All patients had multisystem traumas and developed the adult respiratory distress syndrome in the post- operative period. Criteria used to identify ARDS included ventilatory support for greater than 96 hr, exclusion of specific car- diopulmonary problems, an intrapulmonary shunt >25%, an arterial oxygen tension on 100% inspired oxygen of ~250 Torr, and a chest radiograph with diffuse interstitial edema [ 171. Patients were included if they had persistent pulmonary artery hyperten- 243 O@22-4804/82/030243-06%01.00/O Copyright 0 1982 by Academic Press, Inc. All rights of reproduction in any form rscwed.