Acute respiratory failure (ARF) is common in hematological malignancies patients, notably those with acute leukemia, myelodysplastic syndrome, or allogeneic stem-cell transplantation. ARF is the leading reason for intensive care unit (ICU) admission, with a 35% case fatality. Failure to identify the ARF cause is associated with mortality. A prompt well-designed diagnostic workup is crucial. The investigations are chosen according to pre-test diagnostic probabilities, estimated by the …