Asthma in infancy and toddlers has been increasingly recognized, referring to recurrent episodes of wheezing, also in mechanically ventilated children [1]. We analyzed the working pressures of the respiratory system under static conditions in a cohort of infants and toddlers with a discharge diagnosis of critical asthma. Also, we compare them with critical bronchiolitis cohort and anesthetized children without respiratory disease (normal physiology). Finally, we aimed to identify consistent thresholds in lung mechanics to discriminate between these conditions.