We read with interest the recent article by Sonnenberg et al,1 and we agree wholeheartedly that the increasing use of novel in situ and ex situ machine perfusion techniques mandate rapid changes to the way that national donation and transplant registries collect and disseminate deceased donor data. Importantly, the authors also emphasize that accurate registry data collection and updated definitions of time points around deceased donation and transplantation are likely to aid in the retrospective identification of optimal organ preservation techniques. These advances will also have potentially far-reaching effects on risk-adjustment models incorporated into transplant center outcome oversight programs. However, we do note that Sonnenberg et al propose that the time from cross-clamp in the deceased donor to reperfusion in the recipient be renamed as "total ex situ time." Given that normothermic regional perfusion is increasingly used in controlled donation after circulatory death donors2 and that in situ warm perfusion often occurs for 2 h or so using this technique, the label of "total ex situ time" may not be entirely helpful. Furthermore, other authors have demonstrated that the time to explant a deceased donor organ likely influences graft outcomes.3 Terminology that implicitly acknowledges that machine perfusion may happen in situ or ex situ (or continuously4) and avoids assumptions regarding the timing of organ explant would be beneficial. Therefore, we suggest that the term "total preservation time" may better reflect the period between deceased donor aortic cross-clamp and reperfusion in the recipient. This assumes that the time of initial donor cross-clamp (or any other technique for vascular occlusion) is a reasonable approximation for the start of surgical donor perfusion either with cold or warm perfusate. In the United Kingdom, data sets that can capture relevant machine perfusion data have been developed and are being implemented and further refined. Registries (and the terminologies they use) must evolve to reflect changes in clinical practice, and aligning registries with international recommendations would be advantageous.5 We look forward to the advances in organ transplantation that will result from analyses of such data in the future.

Response to “Following the Flow: Changes in Organ Preservation Methods Require Changes in Our Data Collection”