Combination of active compression decompression cardiopulmonary resuscitation and the inspiratory impedance threshold device: state of the art.

PURPOSE OF REVIEW Over the past decade, the combination of active compression decompression (ACD) cardiopulmonary resuscitation (CPR) and an impedance threshold device (ITD) has been shown to significantly increase vital organ perfusion pressures and survival rates in animals and humans. The purpose of this review article is to summarize the recent advances with this new technology. RECENT FINDINGS Building upon animal studies that demonstrated the benefit of the ITD used with either ACD CPR or standard CPR (S-CPR), four prospective, randomized clinical trials with ACD/ITD CPR have been recently completed. One blinded, out-of-hospital cardiac arrest trial (n = 21 patients) demonstrated that systemic blood pressures and coronary perfusion pressures were markedly higher when ACD/ITD CPR was used when compared directly with ACD CPR alone. The second blinded trial demonstrated that the combination of ACD/ITD CPR was effective with both a facemask and an endotracheal tube (n = 15 patients). A third randomized clinical trial (n = 210 patients) demonstrated that 24-hour survival rates for out-of-hospital cardiac arrest were more than 65% higher with ACD/ITD CPR than with S-CPR (P < 0.01). Neurologic function after cardiac arrest trended higher in patients with witnessed arrest who received ACD/ITD CPR than in those who received S-CPR(P < 0.07). In addition, when ACD/ITD CPR was applied later in the course of treatment, short-term survival rates were threefold higher in patients receiving ACD/ITD CPR (44%) than in those receiving S-CPR (14%)(P < 0.05). In that study, patients with the greatest chance for survival-those with witnessed cardiac arrest and an initial rhythm of ventricular fibrillation-had a 23% 24-hour survival rate with S-CPR versus a 58% 24-hour survival rate with ACD/ITD CPR (P < 0.01). It should be noted that this trial was performed in a city where an earlier study found no difference in outcomes between ACD CPR alone and S-CPR. The fourth clinical trial was a randomized, double-blinded study of 400 patients with out-of-hospital cardiac arrest treated by advanced life support personnel. All patients received ACD CPR: half were treated with a sham ITD and the other half were treated with an active ITD. Twenty-four hour survival, the primary endpoint, was 32% in the active ITD group versus 22% in the sham group (P < 0.05). SUMMARY On the basis of the cumulative findings of these studies, it is concluded that ACD/ITD CPR provides superior vital organ blood flow and results in significantly higher short-term survival rates than do ACD CPR alone or S-CPR. Use of the ACD/ITD CPR technology optimizes perfusion of the heart and brain during cardiac arrest and results in the highest reported survival rates of any CPR device technology. Use of this technology should be encouraged while additional studies are under way to examine the potential long-term impact of this new technology.