Low-dose versus high-dose heparinization during arteriovenous carbon dioxide removal

The purpose of this study was to compare low-dose (LD) and high-dose (HD) s ystemic heparinization in a prospective randomized study of arteriovenous c arbon dioxide removal (AVCO(2)R) during acute respiratory distress syndrome , using a commercially available heparin-coated oxygenator. Adult sheep (n= 13) received an LD50 smoke inhalation and 40% TBSA third degree cutaneous f lame burn injury. At 40-48h post-injury animals underwent cannulation of th e carotid artery and jugular vein and were then randomized to HD heparin (a ctivated clotting time, ACT>300s, n=6) and LD heparin (ACT<200 s, n=7)and p laced on AVCO(2)R for approximately 72 h using an oxygenator with the Trill ium Bio-Passive Surface(TM). Mean ACTs were significantly different, as exp ected (HD: 446<plus/minus>26 s, LD: 213 +/- 12 s, p<0.05). AVCO(2)R shunt f low averaged approximately 13% of cardiac output with mean CO2 removal simi lar in HD and LID, p=NS. The hematocrit, platelet count, and fibrin degrada tion products for the two groups were not different, No differences in thro mbosis or bleeding were noted. In conclusion, LD systemic heparin (ACT<200 s) with a heparin-coated oxygenator does not increase thrombogenicity durin g AVCO(2)R for smoke/burn-induced severe lung injury in sheep.