- Email: [email protected]
Reply to Effects of cardiopulmonary resuscitation time on chest wall compliance in patients with cardiac arrest
G Model
ARTICLE IN PRESS
RESUS-7193; No. of Pages 1
Resuscitation xxx (2017) xxx.e1
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Letter to the Editor Reply to Effects of cardiopulmonary resuscitation time on chest wall compliance in patients with cardiac arrest The authors would like to thank Dr Oh for his insightful comments on our publication focusing on the changes in chest compliance during CPR in a human cadaver model [1,2]. Dr. Oh introduced the idea that bone fractures could be in part responsible for many of the changes in chest compliance observed in the study. However, only two of the nine cadavers we studied had rib or sternal fractures. Therefore, fractures are not the primary mechanism for the observed chest softening during CPR. In swine in cardiac arrest, we have measured compression force and distance precisely. In those studies, we have also observed changes in compliance during CPR over time, in the absence of rib and sternal fractures. Dr Oh also suggested that application of our study’s result should be limited to active compression and decompression (ACD, ResQPUMP, ZOLL, Chelmsford, MA) devices. In our study the ACD device was only utilized to measure the static displacement of the chest at the prescribed forces, but CPR was not performed with it. CPR was performed with an automated mechanical device (LUCAS 2 device; Physio-Control Inc./Jolife AB, Lund, Sweden). The LUCAS device is not capable of active decompression CPR. More importantly, the LUCAS device only returns the chest to the original zero point during decompression, whereas actual ACD lifts the chest 1 cm–2.5 cm beyond the original chest wall height depending on how much lift force is applied. As such, an additional benefit of ACD is that even if a subject experiences broken ribs during CPR, ACD ensures full chest wall recoil which does not occur with the manual or currently available automated CPR methods. As proposed by Dr Oh, we are currently performing further studies to try to understand the exact effects of CPR on chest wall compliance in various conditions and the mechanism of modification of chest compliance. Statement of authorship All authors have participated to the conception, design and writing of this manuscript. This manuscript represents valid work and that neither this manuscript nor one with substantially similar content under our authorship has been published or is being considered for publication elsewhere.
Conflict of interest Dr. Metzger is employed by Zoll, the manufacturer of the ResQPump. Dr. Segal has no conflict of interest. Funding source None. Prior publication None. Copyright constraints None. References [1].Segal N, Robinson AE, Berger PS, Lick MC, Moore JC, Salverda BJ, et al. Changes in anteroposterior chest height measured during static chest compression and decompression with a ResQPUMP reveal chest compliance alteration in human cadavers. Resuscitation 2017;116:56–9. [2].Oh JH. Effects of cardiopulmonary resuscitation time on chest wall compliance in patients with cardiac arrest. Resuscitation 2017, in press.
Nicolas Segal Department of Emergency Medicine, University of Minnesota, Minneapolis, MN, United States a
Anja K. Metzger a,b,∗ Department of Emergency Medicine, University of Minnesota, Minneapolis, MN, United States b ZOLL Medical, Minneapolis, MN, United States
∗ Corresponding
author at: 1905 County Rd C West, Roseville, MN 55113, United States. E-mail addresses: [email protected] (N. Segal), [email protected] (A.K. Metzger). 17 May 2017
http://dx.doi.org/10.1016/j.resuscitation.2017.05.021 0300-9572/© 2017 Published by Elsevier Ireland Ltd.
Please cite this article in press as: Segal N, Metzger AK. Reply to Effects of cardiopulmonary resuscitation time on chest wall compliance in patients with cardiac arrest. Resuscitation (2017), http://dx.doi.org/10.1016/j.resuscitation.2017.05.021
ARTICLE IN PRESS
RESUS-7193; No. of Pages 1
Resuscitation xxx (2017) xxx.e1
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Letter to the Editor Reply to Effects of cardiopulmonary resuscitation time on chest wall compliance in patients with cardiac arrest The authors would like to thank Dr Oh for his insightful comments on our publication focusing on the changes in chest compliance during CPR in a human cadaver model [1,2]. Dr. Oh introduced the idea that bone fractures could be in part responsible for many of the changes in chest compliance observed in the study. However, only two of the nine cadavers we studied had rib or sternal fractures. Therefore, fractures are not the primary mechanism for the observed chest softening during CPR. In swine in cardiac arrest, we have measured compression force and distance precisely. In those studies, we have also observed changes in compliance during CPR over time, in the absence of rib and sternal fractures. Dr Oh also suggested that application of our study’s result should be limited to active compression and decompression (ACD, ResQPUMP, ZOLL, Chelmsford, MA) devices. In our study the ACD device was only utilized to measure the static displacement of the chest at the prescribed forces, but CPR was not performed with it. CPR was performed with an automated mechanical device (LUCAS 2 device; Physio-Control Inc./Jolife AB, Lund, Sweden). The LUCAS device is not capable of active decompression CPR. More importantly, the LUCAS device only returns the chest to the original zero point during decompression, whereas actual ACD lifts the chest 1 cm–2.5 cm beyond the original chest wall height depending on how much lift force is applied. As such, an additional benefit of ACD is that even if a subject experiences broken ribs during CPR, ACD ensures full chest wall recoil which does not occur with the manual or currently available automated CPR methods. As proposed by Dr Oh, we are currently performing further studies to try to understand the exact effects of CPR on chest wall compliance in various conditions and the mechanism of modification of chest compliance. Statement of authorship All authors have participated to the conception, design and writing of this manuscript. This manuscript represents valid work and that neither this manuscript nor one with substantially similar content under our authorship has been published or is being considered for publication elsewhere.
Conflict of interest Dr. Metzger is employed by Zoll, the manufacturer of the ResQPump. Dr. Segal has no conflict of interest. Funding source None. Prior publication None. Copyright constraints None. References [1].Segal N, Robinson AE, Berger PS, Lick MC, Moore JC, Salverda BJ, et al. Changes in anteroposterior chest height measured during static chest compression and decompression with a ResQPUMP reveal chest compliance alteration in human cadavers. Resuscitation 2017;116:56–9. [2].Oh JH. Effects of cardiopulmonary resuscitation time on chest wall compliance in patients with cardiac arrest. Resuscitation 2017, in press.
Nicolas Segal Department of Emergency Medicine, University of Minnesota, Minneapolis, MN, United States a
Anja K. Metzger a,b,∗ Department of Emergency Medicine, University of Minnesota, Minneapolis, MN, United States b ZOLL Medical, Minneapolis, MN, United States
∗ Corresponding
author at: 1905 County Rd C West, Roseville, MN 55113, United States. E-mail addresses: [email protected] (N. Segal), [email protected] (A.K. Metzger). 17 May 2017
http://dx.doi.org/10.1016/j.resuscitation.2017.05.021 0300-9572/© 2017 Published by Elsevier Ireland Ltd.
Please cite this article in press as: Segal N, Metzger AK. Reply to Effects of cardiopulmonary resuscitation time on chest wall compliance in patients with cardiac arrest. Resuscitation (2017), http://dx.doi.org/10.1016/j.resuscitation.2017.05.021