Limitations
Several limitations of the present study warrant mention. First, the study was inherently limited by its observational retrospective design. Second, the number of cases analyzed was small, and this may have introduced bias. Third, unsuccessful weaning off ECMO support in patient without pulse pressure could not be clearly explained because pulse pressure may have been influenced by degree of remaining myocardial function after CPR. Furthermore, successful revascularization of AMI may have affected cardiac function recovery and be related to pulse pressure and successful weaning off ECMO support. We attempted subgroup analysis to minimize bias, but the small sample size prevented meaningful analysis. Nevertheless, our finding indicate that patients with the loss of pulse pressure immediately after ECPR are unlikely to be successfully weaned off ECMO support, and thus, we recommend that such patients require more careful management after ECPR. Forth, no clear definition of pulse pressure is avalable, and thus we defined it by adopting the definition provided in “Extracorporeal Life Support: The ELSO Red Book 5th edition” and used in previous report.16,17 In future, consensus should be determined for pulse pressure. Finally, because high dose vasopressor induced peripheral artery spasms, pulse pressure measurements at peripheral arteries, such as radial artery, may have an error.