doi: 10.1161/CIRCULATIONAHA.108.772202
(Circulation. 2008;117:e494.)
© 2008 American Heart Association, Inc.
Correspondence |
Response to Letter Regarding Article "Improved Neurological Outcome With Continuous Chest Compressions Compared With 30:2 Compressions-to-Ventilations Cardiopulmonary Resuscitation in a Realistic Swine Model of Out-of-Hospital Cardiac Arrest"
University of Arizona Sarver Heart Center, University of Arizona College of Medicine, Tucson, Ariz
University of Basel, Basel, Switzerland
We are pleased to be able to respond to the concerns about chest compressions without ventilations for victims of out-of-hospital cardiac arrest expressed by Rottenberg and the relevance of our swine model to patients. Similar concerns by others are in part the reason why continuous-chest-compression cardiopulmonary resuscitation (CCC CPR) has not as yet been included in Guidelines.
As Rottenberg noted, in humans, the tongue, soft palate, and/or the epiglottis may act as a 1-way valve. This may result in partial obstruction, but it does not prevent the gasping effort. In fact, this partial or complete upper airway obstruction during cardiac arrest may be beneficial, as the gasping effort with an obstructed upper airway results in a negative intrathoracic pressure (simulating an inspiratory impedance threshold valve) that enhances venous return to the chest and improves organ blood flow.1 Some air movement occurs in humans with gasping or agonal breathing, as evidence by the noise; if there were no air flow, there would be no noise.
The concern about the application of CCC CPR to in-home arrest is not well founded. The reason in-home survival was less in the report by Herlitz et al2 is that, as they reported, the patients were older, were more often women, had arrests that were less often witnessed, were less likely to receive bystander CPR, were less often in VF, and had a longer interval between collapse, start of CPR, and defibrillation. All known factors that decrease survival.
In the article by Whitehurst et al,3 there were no differences in rates of survival. Neither group was successfully defibrillated after 20 minutes of CPR. In the study by Dorph et al,4 the number of swine with return of spontaneous circulation was not different, even though they used an unrealistically short interruption of chest compression (3 seconds rather than a realistic 16 seconds for a single rescuer CPR5), and their protocol paralyzed their animals, which prevented gasping.
The survival rate in our realistic swine model of out-of-hospital cardiac arrest is much better than that found in humans, not only because the technicians performing the resuscitation efforts were young and strong and performed optimal chest compressions with recoil, but also because the swine are young with compliant chests and do not have cardiac or other disease. With this swine model, however, we have shown that survival with CCC CPR was equivalent to ideal 2:15 (ventilations to chest compressions) CPR.6 These findings have been confirmed in humans by a number of studies, including the 2 most recent publications.7 The guidelines were changed from 2:15 to 2:30 based on consensus and not survival studies. Ours is the only survival study to date to compare CCC CPR with 2:30 CPR.8
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Acknowledgments |
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Disclosures
None.
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References |
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 Top References |
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2. Herlitz J, Eek M, Holmberg M, Engdahl J, Holmberg S. Characteristics and outcome among patients having out of hospital cardiac arrest at home compared with elsewhere. Heart. 2002; 88: 579–582.
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8. Ewy GA, Zuercher M, Hilwig RW, Sanders AB, Berg RA, Otto CW, Hayes MM, Kern KB. Improved neurological outcome with continuous chest compressions compared with 30:2 compressions-to-ventilations cardiopulmonary resuscitation in a realistic swine model of out-of-hospital cardiac arrest. Circulation. 2007; 116: 2525–2530.
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