Improving the efficiency of cardiopulmonary resuscitation with an inspiratory impedance threshold valve

Abstract

In an effort to improve the efficiency of cardiopulmonary resuscitation (CPR), a new inspiratory impedance threshold valve has been developed to enhance the return of blood to the thorax during the chest decompression phase. This new device enhances negative intrathoracic pressure during chest wall recoil or the decompression phase, leading to improved vital organ perfusion during both standard CPR and active compression-decompression CPR. With active compression-decompression CPR, addition of the impedance threshold valve results in sustained diastolic pressures of >55 mm Hg in patients in cardiac arrest. The new valve shows promise for patients in asystole or shock refractory ventricular fibrillation, when enhanced return of blood flow to the chest is needed to "prime the pump." The potential long-term benefits of this new valve remain under study.

Inspiratory resistance delays the reporting of symptoms with central hypovolemia: association with cerebral blood flow

“…The ITD includes a specially designed valve that closes when the pressure within the thorax is less than atmospheric pressure and a second valve (termed the safety check valve) that opens at a preset negative intrathoracic pressure. In the spontaneously breathing subject, the ITD creates a small vacuum within the chest, drawing blood from the extrathoracic venous system into the heart each time the subject takes a breath (21,22,25). By increasing preload to the heart, the ITD results in an immediate increase in SBP and DBP (4,5,12,21,25) and a reduction in ICP with a subsequent increase in cerebral perfusion pressure (40) and CBFV (12).…”

“…In the spontaneously breathing subject, the ITD creates a small vacuum within the chest, drawing blood from the extrathoracic venous system into the heart each time the subject takes a breath (21,22,25). By increasing preload to the heart, the ITD results in an immediate increase in SBP and DBP (4,5,12,21,25) and a reduction in ICP with a subsequent increase in cerebral perfusion pressure (40) and CBFV (12). Inspiratory and expiratory pressures were recorded directly from the ITD using a commercial pressure transducer (MKS Instruments, Andover, MA) connected to the face mask, and end-tidal CO2 was measured on a breath-by-breath basis as subjects breathed through the mask (BCI Capnocheck Plus; Smiths Medical, Waukesha, WI).…”

Use of an Inspiratory Impedance Valve Improves Neurologically Intact Survival in a Porcine Model of Ventricular Fibrillation

“…Femoral artery cannulation was performed under aseptic conditions, and arterial blood pressures were monitored and recorded as previously described. 2,6 Continuous ECG monitoring was recorded with a lead II ECG. Data were digitized, recorded, and analyzed as previously described.…”

“…Studies on the mechanism of blood flow during cardiopulmonary resuscitation (CPR) have recently focused on the importance of the decompression phase of CPR. [1][2][3][4] During the decompression phase of standard CPR, a small vacuum is created within the chest relative to the rest of the body every time the chest wall recoils back to its resting position. 5 This draws venous blood back into the right heart.…”

“…6 Although use of the ITV during standard CPR has been reported previously in 2 studies involving Ͼ30 animals, to date there have been no definitive data in support of a survival benefit from the use of the ITV with standard CPR. 4,6 Thus, the purpose of this investigation was to test the hypothesis that the ITV would improve neurological function and 24-hour survival in an established animal model of cardiac arrest during performance of standard CPR.…”