Prevention of catheter thrombosis increases survival, but does not modify lung injury in rats receiving long-term parenteral nutrition

It has previously been shown that rats receiving total parenteral nutrition (TPN) or each component of TPN die within 40 days of treatment. Central catheter thrombosis and lung injury were constant findings. The aim of the present study was to examine the impact of central thrombosis on lung injury and survival in rats receiving long-term parenteral nutrition. In the first part of the study TPN was infused via the jugular vein and incidence of central venous thrombosis and rate of survival were recorded. Addition of low molecular weight heparin (LMWH) reduced central thrombosis from 6 out of 7 animals to 2 out of 7 animals (p=0.027) and increased survival from 17.1±4.5 days to 32.4±4.9 days (p=0.04). In the second part of the study four infusion groups were established. Group 1 (controls) received saline 100 mL/kg/day via the jugular vein (n=6). Group 2 received Intralipid ® 40 mL/kg/day via the jugular vein (n=7). Group 3 received Intralipid 40 mL/kg/day via the portal vein (n=7). Group 4 received Intralipid 40 mL/kg/day with added LMWH 70 U/kg/day (n=7). Lung injury and occurrence of central thrombosis were investigated. Lung injury was assessed by measuring pulmonary arterial pressure (Ppa), clearance of serotonin by the vascular endothelium and the capillary filtration coefficient (CFC). Either infusion via the portal vein or the addition of LMWH to the infusion via the jugular vein prevented central thrombus formation, but the lung injury was not modified by this method compared with infusing Intralipid via the jugular vein without LMWH. In conclusion, central thrombus formation contributes to death in rats receiving parenteral nutrition. The mechanism of the injurious effect of central thrombosis remains unknown, but central thrombus formation seems not to increase lung injury caused by Intralipid.