Inhibition of Enteral Enzymes by Enteroclysis with Nafamostat Mesilate Reduces Neutrophil Activation and Transfusion Requirements after Hemorrhagic Shock

BACKGROUNDThe gut origin of the inflammatory response in trauma patients has been difficult to define. “In vivo” generation of neutrophil-activating factors by gut proteases may be a cause of multiorgan failure after hemorrhagic shock, and can be prevented with the serine protease inhibitor nafamostat mesilate (Futhan). The objective of this study was to determine the effect of nafamostat mesilate given by enteroclysis on enteric serine protease activity, neutrophil activation, and transfusion requirements during hemorrhagic shock. METHODSSixteen pigs weighing 21 to 26 kg were divided into control and treatment groups. A laparotomy was performed under anesthesia, and catheters were placed in the duodenum, midjejunum, and terminal ileum. Pigs were bled 30 mL/kg over 30 minutes and maintained at a mean arterial pressure of 30 mm Hg for 60 minutes. Shed blood was then used to maintain a mean arterial pressure of 45 mm Hg for another 3 hours. Treated animals received 100 mL/kg of 0.37 mmol/L nafamostat mesilate in GoLYTELY through the duodenal catheter at 1 L/h. Control animals received GoLYTELY only. Samples of enteral content and blood were taken at baseline, after shock, and at 30-minute intervals during resuscitation. Animals were killed after 3 hours of resuscitation. Enteral trypsin-like activity at the three gut sites was measured by spectrophotometry. Activation of naive human neutrophils by pig plasma was measured by the percentage of cells having pseudopods larger than 1 μm on microscopy. Lung, liver, and small bowel were analyzed by histology and myeloperoxidase assay. RESULTSBoth control and nafamostat mesilate-treated groups had significant reductions in protein and protease levels in the duodenum during enteroclysis; however, only nafamostat mesilate-treated animals had persistent suppression of protease activity throughout the experiment. Nafamostat mesilate-treated animals had a lower transfusion requirement of shed blood, 18.1 ± 4.5 mL/kg versus 30 ± 0.43 mL/kg (p = 0.002). Nafamostat mesilate-treated animals had significantly less neutrophil activation than controls at 150 minutes after resuscitation (33.7 ± 6.48% vs. 42.4 ± 4.57%, p = 0.01) and 180 minutes after resuscitation (31.1 ± 3.31% vs. 46.9 ± 4.53%, p = 0.0002). Lung myeloperoxidase activity was lower in nafamostat mesilate-treated animals (0.31 ± 0.14) than in control animals (0.16 ± 0.04, p = 0.04). Histology of liver and small intestine showed less injury in nafamostat mesilate-tr