Date Published: February 27, 2019
Publisher: Public Library of Science
Author(s): Kurt Ruetzler, Steve Leung, Mark Chmiela, Eva Rivas, Lukasz Szarpak, Sandeep Khanna, Guangmei Mao, Richard L. Drake, Daniel I. Sessler, Alparslan Turan, Andrea Coppadoro.
High-quality chest compressions are imperative for Cardio-Pulmonary-Resuscitation (CPR). International CPR guidelines advocate, that chest compressions should not be interrupted for ventilation once a patient’s trachea is intubated or a supraglottic-airway-device positioned. Supraglottic-airway-devices offer limited protection against pulmonary aspiration. Simultaneous chest compressions and positive pressure ventilation both increase intrathoracic pressure and potentially enhances the risk of pulmonary aspiration. The hypothesis was, that regurgitation and pulmonary aspiration is more common during continuous versus interrupted chest compressions in human cadavers ventilated with a laryngeal tube airway.
Twenty suitable cadavers were included, and were positioned supine, the stomach was emptied, 500 ml of methylene-blue-solution instilled and laryngeal tube inserted. Cadavers were randomly assigned to: 1) continuous chest compressions; or, 2) interrupted chest compressions for ventilation breaths. After 14 minutes of the initial designated CPR strategy, pulmonary aspiration was assessed with a flexible bronchoscope. The methylene-blue-solution was replaced by 500 ml barium-sulfate radiopaque suspension. 14 minutes of CPR with the second designated ventilation strategy was performed. Pulmonary aspiration was then assessed with a conventional chest X-ray.
Two cadavers were excluded for technical reasons, leaving 18 cadavers for statistical analysis. Pulmonary aspiration was observed in 9 (50%) cadavers with continuous chest compressions, and 7 (39%) with interrupted chest compressions (P = 0.75).
Our pilot study indicate, that incidence of pulmonary aspiration is generally high in patients undergoing CPR when a laryngeal tube is used for ventilation. Our study was not powered to identify potentially important differences in regurgitation or aspiration between ongoing vs. interrupted chest compression. Our results nonetheless suggest that interrupted chest compressions might better protect against pulmonary aspiration when a laryngeal tube is used for ventilation.
More than 350,000 people suffer out-of-hospital cardiac arrests annually in the United States. Early initiation of advanced cardiopulmonary resuscitation (CPR) is key to favorable outcomes. Airway management is also crucial, and adequate ventilation and oxygenation is essential.
Human cadavers were provided by the Department of Anatomy of the Cleveland Clinic Lerner College of Medicine. At the Cleveland Clinic the IRB has determined that since the cadavers used in research studies are donated through the Cleveland Clinic Body Donation Program the Director of that program, Dr. Richard Drake, will provide final approval for all studies using cadavers. There does not need to be a separate IRB approval.
We studied 20 cadavers, but two were excluded for technical reasons, one assigned to each initial treatment. Therefore 18 cavers were included in the statistical analyses, 9 starting with continuous chest compressions and 9 starting with interrupted chest compressions S1 Table. The characteristics of cadavers was summarized in Table 1. Overall, 7 (39%) were female; the mean of age was 66 (SD = 12) and the mean of BMI was 26 (SD = 6).
Interruption of chest compressions decrease coronary perfusion pressure, reduce rate of return of spontaneous circulation (ROSC), diminish defibrillation success, and unsurprisingly are associated with poor outcome. Consequently, interruptions should be kept as short as necessary and avoided when practical.[4, 6, 20] Several observational studies reported significant increases in survival rates among patients having CPR, at least in patients with a shockable rhythm.[24–26] although by far the largest prospective trial investigating the impact of continuous versus interrupted chest compression, failed to demonstrate any increase of survival and favorable neurologic function in patients suffering from out-of-hospital CPR. Nonetheless, current CPR guidelines advocate continuous chest compressions once the airway is secured by an endotracheal tube or a supraglottic airway device.[4, 20]