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Response to: The difference in the association between included ECPR patients and neurological outcomes

The Original Article was published on 25 January 2023

The Original Article was published on 08 December 2022

Dear editor,

We express our gratitude to Hifumi and their associates for their interest in our manuscript pertaining to the utilization of targeted temperature management (TTM) among patients treated with extracorporeal membrane oxygenation (ECMO) [1].

As noted, the optimal target temperature may vary contingent upon the aetiology of arrest. While 91% of our study cohort had a cardiac cause of arrest, the impact of the remaining patients on the outcome of our study may be non-negligible. Therefore, we conducted a sensitivity analysis that included only the patients with a cardiac cause of arrest and found the results to be consistent (see Table 1).

Table 1 Sensitivity analysis (including only the patients with a cardiac cause of arrest)

We concur that there may be an inherent bias, specifically “physician’s discretion”. As Hifumi and colleagues have astutely pointed out, critically ill patients may tend to be treated with higher targeted temperatures. However, we contend that this study possesses a certain degree of robustness as we adjusted for numerous pre- and in-hospital factors that physicians commonly consider when determining target temperature, such as the cause of cardiac arrest, initial documented rhythm at the scene and upon hospital arrival, and time-related variables. Nevertheless, we agree that validation of our findings necessitates an evaluation of the Study of Advanced Life Support for Ventricular Fibrillation with Extracorporeal Circulation in Japan (SAVE-J II) trial, a comprehensive observational study on the same topic that utilizes detailed treatment-related data [2], as well as a meta-analysis. Furthermore, a randomized controlled trial is imperative to determine the optimal target temperature for patients undergoing ECMO.

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Please contact the authors for data requests.


  1. Watanabe M, Matsuyama T, Miyamoto Y, Kitamura T, Komukai S, Ohta B. The impact of different targeted temperatures on out-of-hospital cardiac arrest outcomes in patients receiving extracorporeal membrane oxygenation: a nationwide cohort study. Crit Care. 2022;26:380.

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  2. Inoue A, Hifumi T, Sakamoto T, Okamoto H, Kunikata J, Yokoi H, et al. Extracorporeal cardiopulmonary resuscitation in adult patients with out-of-hospital cardiac arrest: a retrospective large cohort multicenter study in Japan. Crit Care. 2022;26:129.

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This study was supported by the Japan Society for the Promotion of Science KAKENHI (Grant Number 21K16576).

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MW, TM and TK participated in the discussion and wrote the manuscript. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Tasuku Matsuyama.

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The Ethics Committee of each participating hospital approved the study protocol. Each committee waived the need for informed consent because of the de-identification of personal data and observational study design.

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The authors declare that they have no competing interests.

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Watanabe, M., Matsuyama, T. & Kitamura, T. Response to: The difference in the association between included ECPR patients and neurological outcomes. Crit Care 27, 58 (2023).

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