Radioisotope blood volume measurement in uncontrolled retroperitoneal haemorrhage induced by a transfemoral iliac artery puncture

Standard-of-care, large volume crystalloid infusion, in the setting of uncontrolled bleeding, has been challenged and it is not known if fluid resuscitation increases retroperitoneal hemorrhage. We developed an experimental model of retroperitoneal haemorrhage to correlate haemodynamic and metabolic alterations with the blood volume loss. Anaesthetised, spontaneously breathing dogs (17.1±0.56 kg) were randomised 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 min. Initial and final blood volumes were determined using radioactive tracers, 99mTC and 51Cr, respectively. 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, from 131.9±5.9 to 88.6±10.8 mmHg, and a much greater reduction in cardiac output, oxygen delivery and consumption than UL throughout the experiment. Total 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). We conclude that a transfemoral bilateral iliac artery puncture produces a clinically relevant model of uncontrolled retroperitoneal haemorrhage, with hypotension and low flow state, while a unilateral iliac artery lesion causes a compensated shock state.