Intrathoracic pressure regulator during continuous-chest-compression advanced cardiac resuscitation improves vital organ perfusion pressures in a porcine model of cardiac arrest

Demetris Yannopoulos, Vinay M. Nadkarni, Scott H. McKnite, Anu Rao, Kurt Kruger, Anja K Metzger, David G. Benditt, Keith G Lurie

Research output: Contribution to journalArticlepeer-review

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Background-A novel device, the intrathoracic pressure regulator (ITPR), combines an inspiratory impedance threshold device (ITD) with a vacuum source for the generation of controlled -10 mm Hg vacuum in the trachea during cardiopulmonary resuscitation (CPR) while allowing positive pressure ventilation. Compared with standard (STD) CPR, ITPR-CPR will enhance venous return, systemic arterial pressure, and vital organ perfusion in both porcine models of ventricular fibrillation and hypovolemic cardiac arrest. Methods and Results-In protocol 1, 20 pigs (weight, 30±0.5 kg) were randomized to STD-CPR or ITPR-CPR. After 8 minutes of untreated ventricular fibrillation, CPR was performed for 6 minutes at 100 compressions per minute and positive pressure ventilation (100% O 2) with a compression-to-ventilation ratio of 15:2. In protocol 2, 6 animals were bled 50% of their blood volume. After 4 minutes of untreated ventricular fibrillation, interventions were performed for 2 minutes with STD-CPR and 2 minutes of ITPR-CPR. This sequence was repeated. In protocol 3, 6 animals after 8 minutes of untreated VF were treated with ITPR-CPR for 15 minutes, and arterial and venous blood gases were collected at baseline and minutes 5, 10, and 15 of CPR. A newer, leak-proof ITPR device was used. Aortic, right atrial, endotracheal pressure, intracranial pressure, and end-tidal CO 2 values were measured (mm Hg); common carotid arterial flow also was measured (mL/min). Coronary perfusion pressure (diastolic; aortic minus right atrial pressure) and cerebral perfusion pressure (mean arterial minus mean intracranial pressure) were calculated. Unpaired Student t test and Friedman's repeated-measures ANOVA of ranks were used in protocols 1 and 3. A 2-tailed Wilcoxon signed-rank test was used for analysis in protocol 2. Fischer's exact test was used for survival. Significance was set at P<0.05. Vital organ perfusion pressures and end-tidal CO 2 were significantly improved with ITPR-CPR in both protocols. In protocol 1, 1-hour survival was 100% with ITPR-CPR and 10% with STD-CPR (P=0.001). Arterial blood pH was significantly lower and PaCO 2 was significantly higher with ITPR- CPR in protocol 1. Arterial oxygen saturation was 100% throughout the study in both protocols. PaCO 2 and PaO 2 remained stable, but metabolic acidosis progressed, as expected, throughout the 15 minutes of CPR in protocol 3. Conclusions-Compared with STD-CPR, use of ITPR-CPR improved hemodynamics and short-term survival rates after cardiac arrest.

Original languageEnglish (US)
Pages (from-to)803-811
Number of pages9
Issue number6
StatePublished - Aug 9 2005


  • Cardiopulmonary resuscitation
  • Cerebrovascular circulation
  • Circulation
  • Perfusion
  • Resuscitation


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