INTRODUCTION: The combination of the LUCAS 2 (L-CPR) automated CPR device and an impedance threshold device (ITD) has been widely implemented in the clinical field. This animal study tested the hypothesis that the addition of an ITD on L-CPR would enhance cerebral and coronary perfusion pressures. METHODS: Ten female pigs (39.0 +/- 2.0 kg) were sedated, intubated, anesthetized with isofluorane, and paralyzed with succinylcholine (93.3 mug/kg/min) to inhibit the potential confounding effect of gasping. After 4 min of untreated ventricular fibrillation, 4 min of L-CPR+an active ITD or L-CPR+a sham ITD was initiated and followed by another 4 min of the alternative method of CPR. Systolic blood pressure (SBP), diastolic blood pressure (DBP), diastolic right atrial pressure (RAP), intracranial pressure (ICP), airway pressure, and end tidal CO2 (ETCO2) were recorded continuously. Data expressed as mean mmHg +/- SD. RESULTS: Decompression phase airway pressure was significantly lower with L-CPR+active ITD versus L-CPR+sham ITD (-5.3 +/- 2.2 vs. -0.5 +/- 0.6; p<0.001). L-CPR+active ITD treatment resulted in significantly improved hemodynamics versus L-CPR+sham ITD: ETCO2, 35 +/- 6 vs. 29 +/- 7 (p=0.015); SBP, 99 +/- 9 vs. 93 +/- 15 (p=0.050); DBP, 24 +/- 12 vs. 19 +/- 15 (p=0.006); coronary perfusion pressure, 29 +/- 8 vs. 26 +/- 7 (p=0.004) and cerebral perfusion pressure, 24 +/- 13 vs. 21 +/- 12 (p=0.028). CONCLUSIONS: In pigs undergoing L-CPR the addition of the active ITD significantly reduced intrathoracic pressure and increased vital organ perfusion pressures.