Critical COVID-19 patients through first, second, and third wave: retrospective observational study comparing outcomes in intensive care unit

Irene Coloretti, Carlotta Farinelli, Emanuela Biagioni, Ilenia Gatto, Elena Munari, Lorenzo Dall’Ara, Stefano Busani, Marianna Meschiari, Roberto Tonelli, Cristina Mussini, Giovanni Guaraldi, Andrea Cossarizza, Enrico Clini, Massimo Girardis; the MO-COVID19 Working Group