G Model
ARTICLE IN PRESS
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Contents lists available at ScienceDirect
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Letter to the Editor Reply to Letter: Re: Use of rapid sequence intubation predicts improved survival among patients intubated after out-of-hospital cardiac arrest Sir, We thank Drennan et al.1 for their interest. Regarding airway training and experience in the EMS system under study, there may be less variability between paramedics and agencies than Drennan et al. assume. All paramedics complete advanced airway training that includes didactics, high-fidelity simulation, intubating experience in the operating room and substantial opportunity for intubating critically ill patients in the prehospital setting.2,3 They complete at least forty-five intubations during the initial training period, and, thereafter, paramedics perform an average of fifteen intubations annually in the field. Paramedics also participate in continuous quality improvement activities, including recording all airway management attempts into an electronic database.4 We agree that observational studies of advanced airway management following cardiac arrest, including ours, are vulnerable to confounding by indication. A primary reason is that neurological status at the time of EMS arrival is closely related to both advanced airway management, i.e., the decision to intubate, and prognosis. This decision occurs differently in systems with and without rapid sequence intubation capability and may explain the associations between intubation status and survival observed in different studies. In our study, patients who were intubated without paralytic medications had much worse survival that either those who required rapid sequence intubation or who were not intubated at all. We suspect that the poor prognosis of the first group (intubation without paralytics) was related to diminished brainstem function and airway reflexes, secondary to more protracted and severe brain ischemia, at the time of EMS arrival. In studies that occurred in EMS systems without rapid sequence intubation capability, patients who were intubated (again, without paralytics) might similarly have had a worse prognosis than those who were not intubated, due to worse neurological function at the time of EMS arrival. Drennan et al. write that “Recent studies have shown that prehospital intubation can have a detrimental effect on patient
survival.” Because of the potential for bias related to confounding by indication and other unaccounted factors, we caution against making conclusions regarding the effectiveness of airway management from any observational study, including our own. Our study should not be considered evidence of the superiority of rapid sequence intubation over other airway management approaches. However, it adds to the existing literature by suggesting that confounding by indication may have biased the negative association between intubation and survival observed in other studies. Conflict of interest statement The authors have no conflicts of interest to declare. References 1. Drennan IR, Diao L, Allen KS, et al. Re: Use of rapid sequence intubation predicts improved survival among patients intubated after out-of-hospital cardiac arrest. Resuscitation 2014, http://dx.doi.org/10.1016/j.resuscitation.2014.03.317. 2. Grabinsky A, Rea TD, Damm M, et al. Training for success. Strategies & core components to improve airway management. JEMS 2011;36:44–7. 3. Warner KJ, Carlbom D, Cooke CR, et al. Paramedic training for proficient prehospital endotracheal intubation. Prehosp Emerg Care 2010;14:103–8. 4. Prekker ME, Kwok H, Shin J, et al. The process of prehospital airway management: challenges and solutions during paramedic endotracheal intubation. Crit Care Med 2014 [Epub ahead of print].
Heemun Kwok ∗ Matthew Prekker Andreas Grabinsky David Carlbom Thomas D. Rea University of Washington School of Medicine, Seattle, WA, United States ∗ Corresponding
author at: Division of Emergency Medicine, Box 359702, 325 Ninth Avenue, Seattle, WA 98104, United States. E-mail address: [email protected] (H. Kwok) 11 April 2014
http://dx.doi.org/10.1016/j.resuscitation.2014.04.014 0300-9572/© 2014 Published by Elsevier Ireland Ltd.
Please cite this article in press as: Kwok H, et al. Reply to Letter: Re: Use of rapid sequence intubation predicts improved survival among patients intubated after out-of-hospital cardiac arrest. Resuscitation (2014), http://dx.doi.org/10.1016/j.resuscitation.2014.04.014
ARTICLE IN PRESS
RESUS-5974; No. of Pages 1
Resuscitation xxx (2014) xxx.e1
Contents lists available at ScienceDirect
Resuscitation journal homepage: www.elsevier.com/locate/resuscitation
Letter to the Editor Reply to Letter: Re: Use of rapid sequence intubation predicts improved survival among patients intubated after out-of-hospital cardiac arrest Sir, We thank Drennan et al.1 for their interest. Regarding airway training and experience in the EMS system under study, there may be less variability between paramedics and agencies than Drennan et al. assume. All paramedics complete advanced airway training that includes didactics, high-fidelity simulation, intubating experience in the operating room and substantial opportunity for intubating critically ill patients in the prehospital setting.2,3 They complete at least forty-five intubations during the initial training period, and, thereafter, paramedics perform an average of fifteen intubations annually in the field. Paramedics also participate in continuous quality improvement activities, including recording all airway management attempts into an electronic database.4 We agree that observational studies of advanced airway management following cardiac arrest, including ours, are vulnerable to confounding by indication. A primary reason is that neurological status at the time of EMS arrival is closely related to both advanced airway management, i.e., the decision to intubate, and prognosis. This decision occurs differently in systems with and without rapid sequence intubation capability and may explain the associations between intubation status and survival observed in different studies. In our study, patients who were intubated without paralytic medications had much worse survival that either those who required rapid sequence intubation or who were not intubated at all. We suspect that the poor prognosis of the first group (intubation without paralytics) was related to diminished brainstem function and airway reflexes, secondary to more protracted and severe brain ischemia, at the time of EMS arrival. In studies that occurred in EMS systems without rapid sequence intubation capability, patients who were intubated (again, without paralytics) might similarly have had a worse prognosis than those who were not intubated, due to worse neurological function at the time of EMS arrival. Drennan et al. write that “Recent studies have shown that prehospital intubation can have a detrimental effect on patient
survival.” Because of the potential for bias related to confounding by indication and other unaccounted factors, we caution against making conclusions regarding the effectiveness of airway management from any observational study, including our own. Our study should not be considered evidence of the superiority of rapid sequence intubation over other airway management approaches. However, it adds to the existing literature by suggesting that confounding by indication may have biased the negative association between intubation and survival observed in other studies. Conflict of interest statement The authors have no conflicts of interest to declare. References 1. Drennan IR, Diao L, Allen KS, et al. Re: Use of rapid sequence intubation predicts improved survival among patients intubated after out-of-hospital cardiac arrest. Resuscitation 2014, http://dx.doi.org/10.1016/j.resuscitation.2014.03.317. 2. Grabinsky A, Rea TD, Damm M, et al. Training for success. Strategies & core components to improve airway management. JEMS 2011;36:44–7. 3. Warner KJ, Carlbom D, Cooke CR, et al. Paramedic training for proficient prehospital endotracheal intubation. Prehosp Emerg Care 2010;14:103–8. 4. Prekker ME, Kwok H, Shin J, et al. The process of prehospital airway management: challenges and solutions during paramedic endotracheal intubation. Crit Care Med 2014 [Epub ahead of print].
Heemun Kwok ∗ Matthew Prekker Andreas Grabinsky David Carlbom Thomas D. Rea University of Washington School of Medicine, Seattle, WA, United States ∗ Corresponding
author at: Division of Emergency Medicine, Box 359702, 325 Ninth Avenue, Seattle, WA 98104, United States. E-mail address: [email protected] (H. Kwok) 11 April 2014
http://dx.doi.org/10.1016/j.resuscitation.2014.04.014 0300-9572/© 2014 Published by Elsevier Ireland Ltd.
Please cite this article in press as: Kwok H, et al. Reply to Letter: Re: Use of rapid sequence intubation predicts improved survival among patients intubated after out-of-hospital cardiac arrest. Resuscitation (2014), http://dx.doi.org/10.1016/j.resuscitation.2014.04.014
