by two-fold to three-fold, 5 may be a key factor influencing the therapeutic effects of other potential therapeutic interventions like TTM in the postresuscitation period. We therefore analysed all available data from larger clinical trials, focusing on therapeutic hypothermia and TTM, 2-4 and compared bystander CPR rates and the effects of TTM. Results from the analysis of pooled data from these publications support the hypothesis that populations with lower bystander CPR rates benefit much more from TTM than those with very high bystander-CPR rates (Fig. 1). From our results we thus conclude that therapeutic hypothermia and TTM may not be effective when administered following very short periods of cardiac arrest -due to very high bystander CPR rates -consequently resulting in only mild cerebral insults. In addition, with a very late onset of reaching target temperature, 3,4 the application of TTM may have been outside the window of therapeutic opportunities. 1 Further studies may investigate this most important relationship.

6 Mallet V, Keta-Cov research group. Reply to: 'Progressive cholangiopathy in COVID-19 patients: other possible diagnoses than ketamine-induced cholangiopathy should be considered'. J Hepatol 2021; 75:990-992. 7 ANSM. Ketamine: risque d'atteintes h epatiques graves lors d'utilisation prolong ee et/oua `doses elev ees -lettre aux preofessionnels de sant e. 2017.