Iliac artery lesions as experimental models of vascular trauma inducing intraperitoneal and retroperitonial hemorrhage

1. Applied Physiology Service, Instituto do Coração/Faculdade de Medicina da USP (InCor/FMUSP). Dept. of Surgery, Universidade Federal de São Paulo/Escola Paulista de Medicina (UNIFESP/EPM). 2. Applied Physiology Service, InCor/FMUSP. 3. Emergency Service, Dept. of Surgery, Faculdade de Ciências Médicas da Santa Casa de São Paulo. SummaryObjective: The initial treatment of uncontrolled hemorrhage is controversial. Therefore, the objective of this study was to develop an experimental model of retroperitoneal hemorrhage, induced by an iliac artery puncture through the femoral artery, to evaluate its hemodynamic and metabolic consequences and to correlate them with the blood loss volume, measured by radioisotopes. Method: We designed two experimental models of uncontrolled hemorrhage induced by an intraperitoneal and a retroperitoneal iliac artery lesions in dogs (17.1±0.56 kg). In the first set of experiments, a suture was placed through the common iliac artery to produce a 3 mm tear, when the external suture lines were pulled after incision closure, to induce an intraperitoneal hemorrhage. After 20 minutes, the animals were randomized to controls (CT, n=6, no fluids) or to lactated Ringer’s (LR, 32 mL/kg in 15 min, n=6). Intraabdominal blood loss volume was directly measured 40 minutes after the iliac artery tear. In another set of experiments, dogs were randomized to unilateral (UL, n=11) or bilateral (BL, n=11) iliac artery puncture, using a metallic device introduced through the femoral arteries and followed for 120 minutes. Initial and final blood volumes were determined using radioactive tracers, TC and Cr, respectively. Results: In the first set of experiments, all animals presented acute fall in arterial pressure and cardiac output. CT animals remained with severe hypotension and low flows, while LR showed transient improvements in arterial pressure and cardiac output, without promoting significant increases in blood loss volume (CT 47.8±5.9 vs. RL 49.4±0.7, in mL/kg). In the second set of experiments, UL was associated with a stable arterial pressure and a moderate decrease in cardiac output and oxygen delivery. BL induced an abrupt and sustained decrease in mean arterial pressure and a much greater reduction in cardiac output, oxygen delivery and consumption. Retroperitoneal blood loss after BL was 36.8±3.2 ml/kg, while after UL was 25.1±3.4 ml/kg (P=0.0262). Conclusion: Bilateral iliac artery puncture produces hypotension and low flow state, while a unilateral iliac artery lesion causes a compensated shock state. Both the anterior iliac tear or posterior iliac puncture showed to be clinically relevant models of vascular trauma, inducing uncontrolled intraperitoneal and retroperitoneal hemorrhages, respectively.