Abstract
Recent studies have shown that there are three components to CPR that we can utilize to improve neurological survival of cardiac arrest patients. These three components can be implemented in the prehospital management of cardiac arrest patients. Utilization of head and torso elevation, active compression decompression (ACD) CPR and utilization of an impedance threshold device. These techniques and devices show improvement in cerebral and coronary blood flow during cardiac arrest.
Keep Your Head Up and the Pressure Low.
Neuroprotective CPR strategy combining automated head-up positioning (AHUP), an impedance threshold device (ITD), and manual active compression-decompression (ACD) and/or an automated suction-cup based compression device was recently shown in animal models to increase cerebral blood flow and neurologically- intact survival.1. In order to improve patient outcome, head and thorax elevation, so-called head-up position, was shown to strongly reduce ICP while enhancing cerebral perfusion pressure in patients presenting severe traumatic brain injury.2
Hemodynamics were measured utilizing the Seldinger technique through the femoral vein and artery for the continuous monitoring of right atrial and systemic arterial blood pressure. A blood flow probe was placed around the internal carotid artery to monitor carotid blood flow. A pressure gauge was inserted into the parietal lobe of the cerebral cortex after craniotomy to monitor intracranial pressure.2
No problems were seen with head-up/torso-up positioning, but resuscitation rates rose significantly during the transition period (April to June 2015) with an ensuing sustained doubling of those rates over the next 2 years (mean, 34.22%). Outcomes improved across all subgroups and resuscitation rates in 2015-2017 remained comparative to neurologically intact survival (~35-40%) wherever tracked.7
The photo above shows the resuscitation bundle, consisting of an AHUP (EleGARD Patient Positioning System), automated suction-cup based CPR device (LUCAS), and impedance threshold device (ITD).3 This photo shows the head and thorax to be elevated approximately 22 cm and 9 cm. ACD+ITD and head elevation CPR works to lower intracranial pressure by gravitational force enhancing venous return from the head, neck and thorax. This preserves mean arterial pressure during the gradual elevation of the head and thorax.3
Negative Intrathoracic Pressure, Can It Be a Positive Thing?
The impedance threshold device used in this bundle is a small, non-invasive device attached to the end of the endotracheal tube or a BLS supraglottic airway. It was invented to enhance the efficacy of CPR by increasing negative intrathoracic pressure during the decompression phase of CPR without impeding manual ventilation or exhalation.4 Inspiration through the ITD results in an increase in venous blood flow back to the heart and a succeeding increase in cardiac output and blood pressure in hypotensive patients and cardiac arrest patients.5
The device is also shown to increase cardiac and cerebral perfusion pressures nearly four-fold compared to standard CPR.4 This device works on the principle that impedance of inspiratory gas exchange during the decompression or relaxation phase of CPR leads to a greater negative intrathoracic pressure, which results in increased venous return to the heart and lowers intracranial pressures.4
The idea of impeding inspiratory gas exchange, selectively during the chest wall recoil phase of CPR to create a greater pressure differential between the thorax and the rest of the body, thereby enhancing blood flow back to the thorax.4 Randomized studies were completed in prehospital and hospital settings that showed an increase of systolic blood pressure by 100% in the active ITD groups. Diastolic and ETCO2 levels were increased in the active ITD groups as well.6
There was a significant increase in 24-hour survival rates in patients treated with the active ITD (27%) when compared to the sham device (11%).6 Studies in Paris, France, focused on hemodynamics during cardiac arrest; it was found during these trials that systolic and diastolic blood pressures were nearly normal in the active ITD group and ETCO2 levels increased more rapidly and to higher levels with an active ITD.4
Discussion
The incidence of ROSC was 34% in patients treated with the AHUP resuscitation bundle, regardless of interval to placement. This is comparable and even higher than previously reported national ROSC rates (prior to COVID-19).3 Survival to hospital discharge were compared between ACE-CPR (automated control elevations CPR) and C-CPR (conventional CPR), with favorable neurological status (5.9% versus 4.1%).3
The first responders recognized that the time was critical, and they packed BLS items (resuscitator bag, ITD, and supraglottic airway) within the AHUP device carrying case. This provided a way to easily and rapidly carry the AHUP device along with an automated CPR device and an AED to the patient as soon as they arrived on scene. Less immediate equipment and ALS was brought to the patient next, after the AHUP CPR bundle was deployed. 3
All ACE-CPR protocols included rapid initiation of manual CPR followed immediately by use of a manual ACD-CPR device when available, placement of an automated external defibrillator (AED), initiation of ventilation with placement of an ITD on a facemask or airway adjunct, and rapid deployment of the EleGARD applied in less than 6 seconds for minimal CPR interruption. An automated CPR device was deployed per local protocols.2
Below is a flowchart on how the AHUP CPR bundle should be utilized:
References
1. Moore, J., Labarere, J., Debaty, G., Lurie, K., & Pepe, P. (2022). 324 Neuroprotective cardiopulmonary resuscitation to improve survival after cardiac arrest.
2. Levy, Y., Hutin, A., Polge, N., Lidouren, F., Fernandez, R., Kohlhauer, M., … & Tissier, R. (2022). Head and thorax elevation prevents the rise of intracranial pressure during extracorporeal resuscitation in swine. Shock, 58(3), 236-240.
3. Moore, J. C., Pepe, P. E., Scheppke, K. A., Lick, C., Duval, S., Holley, J., … & Labarère, J. (2022). Head and thorax elevation during cardiopulmonary resuscitation using circulatory adjuncts is associated with improved survival. Resuscitation, 179, 9-17.
4. Aufderheide, T. P., & Lurie, K. G. (2006). Vital organ blood flow with the impedance threshold device. Critical care medicine, 34(12), S466-S473.
5. Parsons, D., Convertino, V., Idris, A., Smith, S., Lindstrom, D., Parquette, B., & Aufderheide, T. (2009). The Impedance Threshold Device (ITD-7): A New Device for Combat Casualty Care to Augment Circulation and Blood Pressure in Hypotensive Spontaneously Breathing Warfighters. Army Inst Of Surgical Research Fort Sam Houston, TX.
6. Pirrallo, R. G., Aufderheide, T. P., Provo, T. A., & Lurie, K. G. (2005). Effect of an inspiratory impedance threshold device on hemodynamics during conventional manual cardiopulmonary resuscitation. Resuscitation, 66(1), 13-20.
7. Pepe, P. E., Scheppke, K. A., Antevy, P. M., Crowe, R. P., Millstone, D., Coyle, C., Prusansky, C., Garay, S., Ellis, R., Fowler, R. L., & Moore, J. C. (2019). Confirming the clinical safety and feasibility of a bundled methodology to improve cardiopulmonary resuscitation involving a head-up/torso-up chest compression technique. Critical Care Medicine, 47(3), 449–455. https://doi.org/10.1097/ccm.0000000000003608
