ORGAN BLOOD-FLOW FOLLOWING CARDIAC-ARREST IN A SWINE LOW-FLOW CARDIOPULMONARY BYPASS MODEL

Study objective: To determine organ blood flow changes, relative to ba seline, following cardiac arrest and resuscitation in a closed-chest c ardiac arrest swine model using cardiopulmonary bypass to achieve repr oducible return of spontaneous circulation (ROSC). Interventions: Foll owing 10 min of ventricular fibrillation (VF), animals (n = 10) receiv ed low-flow cardiopulmonary bypass at 10 ml/kg/min from 10- 15 min. At 15 min of VF, norepinephrine (0.12 mg/kg) was given and bypass flow i ncreased to 50 ml/kg/min, followed by countershocks at 16 min. Followi ng ROSC, cardiopulmonary bypass was immediately weaned off with norepi nephrine support. Organ blood flows were determined during normal sinu s rhythm, during reperfusion of VF and during the early post-ROSC peri od while off cardiopulmonary bypass support. Organ blood flows during the early ROSC period were compared with organ blood flow at baseline and during VF. Results: During early reperfusion of VF prior to any dr ug therapy, myocardial, cerebral and abdominal organ blood flows were all low. All animals achieved ROSC at 16.9 +/- 0.7 min and were weaned from bypass in < 5 min following ROSC. During the early post-ROSC per iod, blood flow to the myocardial, cerebral and adrenal vascular beds was significantly elevated relative to baseline. Simultaneously, blood flow to the kidneys, liver, spleen and lungs was reduced relative to baseline. Conclusion: This low-flow bypass model produces reproducible high resuscitation rates and ROSC times. Early post-resuscitation org an blood flow is characterized by a selective hyperemia involving the cerebral, myocardial and adrenal vascular beds, in contrast to hypoper fusion of the pulmonary and mesenteric vascular beds.