To the Editor,
We thank you for the privilege to answer the letter to the editor by Prof. Choi and Dr. Lee.
1
They rose some concerns about the methodology and handling of missing data in our retrospective study “Effect of video laryngoscopy for non-trauma out-of-hospital cardiac arrest on clinical outcome: A registry-based analysis”.
2
First, they pointed out that asystole occurred more often in the DL group, which may have affected patient outcome. Concerning our baseline data, the group of “unfavorable initial rhythms” including asystole and PEA was equally distributed between groups as was the favorable shockable rhythms (VF/VT). Further, we included asystole and PEA as potential confounders in the multivariate regression analysis to control for potential bias here.
Regarding the difference in the rate of intubations performed by emergency physicians, the rate of intubations carried out by EMS staff is nevertheless very low in both groups. VL had often been considered a “rescue option” in difficult airways in the past and may therefore rarely be used by EMS staff. Since some of the EMS staff received “conventional” DL skills training during their in-hospital training they may be more likely to try this option. However, these questions cannot be answered sufficiently from the given registry data. We strongly believe that the above mentioned ideas rather suggest a negative bias towards neurological favorable outcome.
They commented on a high number of missing data in “difficult airway” situations. We critically reviewed this question, since the number of “multiple attempts”, “cricothyrotomy”, and “unknown/not reported” exactly adds up to 100%. The data collection in the registry only allows for “difficult airway situations” the categories intubation complicated > more than 1 attempt, airway access complicated, procedure change and airway access complicated, cricothyrotomy. Therefore, only complicated airway situations needed to be documented, so most of the “unknown” group can be considered “uncomplicated” situations.
As a consequence of the potential bias due to inequity of groups and missing data, the colleagues recommended propensity score matching as the statistical method of choice. We are conscious about the fact that a complex medical treatment as cardiopulmonary resuscitation is prone to a lot of potential confounders and mediators. Therefore, univariate analysis and the differences found herein are not sufficient to demonstrate associations. Matched pair analysis and multivariate logistic regression models both aim to control for potential confounders. When first analyzing the raw data, we carried out a matched pair analysis as well as a multivariate regression model and found similar results confirming the association between VL and CPC1/2 survival. To make the study better readable, we limited it to one method in the final manuscript.
Finally, they commented on the PES categories “mean value”. For explanation and better understanding here, before the analysis numerical values from 0 to 100 have been assigned to the individual PES categories. (For example, PES 1 (no pre-existing disease) = 0, PES 2 (disease without impairment) = 25, etc.). Therefore, the results for PES categories with mean value and standard deviation were given in this way.
Authors' contributions
JR and DF conceptualized, wrote the original draft and the final manuscript. MF supervised, reviewed and edited the final manuscript.
All authors read and approved the final manuscript. The corresponding author had final responsibility to submit for publication.
Funding
There is no funding resource.
Conflict of Interest
All authors declare no conflict of interest.
References
- Does video laryngoscopy significantly improve clinical outcomes in patients with cardiac arrest?.Resuscitation. 2023; 185: 109703
- Effect of video laryngoscopy for non-trauma out-of-hospital cardiac arrest on clinical outcome: A registry-based analysis.Resuscitation. 2023; 185: 109688
Article info
Publication history
Published online: February 15, 2023
Accepted:
February 8,
2023
Received:
February 8,
2023
Identification
Copyright
© 2023 Elsevier B.V. All rights reserved.
ScienceDirect
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- Does video laryngoscopy significantly improve clinical outcomes in patients with cardiac arrest?ResuscitationVol. 185
- PreviewWe read with great interest the article by Risse et al.1 that analyzed the effects of video laryngoscopy (VL) on clinical outcomes in patients with non-traumatic, out-of-hospital cardiac arrest. This retrospective study compared the use of VL (n = 2,201) and direct laryngoscopy (DL; n = 12,186) during cardiopulmonary resuscitation (CPR) in 14,387 patients. They determined that the patients in the VL group had better neurological outcomes. Though the usefulness of VL and importance of oxygenation during CPR is well established,2,3 this study revealed that these factors also improve the neurological outcomes.
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