Hypoxemic respiratory failure (known as type I) Hypoxemic respiratory failure (type I) can be associated with virtually all acute diseases of the lung, such as status asthmaticus, bronchiolitis, pneumonia, and pulmonary edema, which interfere with the normal function of the lung and airway. The predominant mechanism in type I failure is uneven or mismatched ventilation and perfusion (intrapulmonary shunt) in regional lung units. This is the most common form of respiratory failure, characterized by a PaO 2 < 60 mmHg with a normal or low PaCO 2 . The primary treatment of type I respiratory failure in children is to administer supplemental oxygen at a level sufficient to increase the arterial oxygen saturation (SaO 2 ) to greater than 94%. In situations when a fraction of oxygen in inspired gas (FiO 2 ) of greater than 0.5 is necessary to achieve this goal, this often is referred to as "acute hypoxemic respiratory failure" [7] . In this setting, NPPV may be considered.