The prognosis for patients with oncohaematology (POH) has improved over the years [1-3]. Indeed, mortality has decreased, due to therapeutic advances in hematology-oncology [4-6], a reasoned admission policy [7-9] and the progress made in the ICU  as non-invasive ventilation [11,12]. The acute respiratory failure (ARF) is defined by an upper respiratory rate 30 per minute associated with respiratory distress or ambient air Pa02 <60mmHg, or the need for ventilatory support. She enameled changing POH ranging from 5% for solid tumor up to 30% in case of hematological malignancies.  The impact of ventilatory failure is important because half of POH admitted to IRA dies and 75% in case of need for mechanical ventilation [2, 11, 13]. Note that the presence of neutropenia at admission is not a pejorative criterion, attributed his death is questionable. This is essentially the number of organ failure, which affects patient prognosis [15-16].
The etiology of the diagnosis of the IRA also determines the prognosis and mortality attributed to the cardiogenic pulmonary edema is lower than invasive pulmonary aspergillosis. Moreover, the lack of diagnosis correlates with increased mortality .
In a POH with an IRA, the elements must be sought to evoke the most likely diagnoses in order to start urgently, in the early hours, a probabilistic appropriate treatment. The great difficulty is the multiplicity of possible diagnoses in the POH. 
Our clinical strategy is applied to the admission of POH with ARI . It is divided into six items: the time since the beginning of the malignancy or allograft, the type of immune deficiency, the Radiological aspect, the Clinical Experience and knowledge of the literature, the clinical picture and the appearance of the chest CT.
The first factor is the delay between the diagnosis of the disease and the beginning of the IRA. The specific pulmonary or pleural infiltration occurs most often in the early phase of the disease including cases of pulmonary infiltration blast in acute myeloid leukemia . The diagnosis of carcinomatous lymphangitis may also be made to the diagnosis or at relapse of the disease. The bacterial infection and pulmonary edema should be mentioned in all phases of the disease . Opportunistic complications and drug toxicities occurring only later in the disease. 
The second element is the type of immunosuppression induced by the disease. For example an IRA in a patient treated by Flurarabine for chronic lymphocytic leukemia, will evoke a pneumonia carinii pneumonia . Similarly we must learn to evoke pulmonary aspergillosis in chronic dysfunction of neutrophil function [22-24]. Leukemia tricholeucyte can typically complicated by legionella pneumonia. 
The third factor is the radiographic appearance. As the clinical examination, radiological signs lack specificity. The standard radiology is usually put in default. There is no correlation between the etiology of respiratory failure and radiographic presentation. Thus in 116 HIV patients chest radiography allowed a diagnosis in 34% of cases, including cases of Pneumocystis pneumonia. This poor sensitivity has led to consider as unnecessary chest radiography in the assessment of febrile neutropenia, high resolution chest CT (HRCT) in showing more than 60% of cases of infectious-stage abnormalities in neutropenic patients with radiographic chest is normal. However the presence of radiological abnormality may contribute to diagnosis, the presence of nodule towards a tumor etiology or septic emboli, systematized abnormalities or lobar moving towards an acute infectious pneumonitis.
The fourth speaker in the reflection is the clinical experience and knowledge of literature (clinical and experimental autopsy).
The fifth factor to consider is the evaluation of the clinical picture. Respiratory symptoms such as chest pain or hemoptysis moving towards pulmonary aspergillosis. The extra-thoracic signs may also be an aid to diagnosis.Skin septic emboli are seen in Candida infections or sepsis. Fever and intensity, reaching effusion, articular and ophthalmic involvement participate in the diagnostic discussion . Interestingly the time between onset of symptoms and admission in ICU can provide guidance to identify clinical reference tables .
Differences depending on the type of immunosuppression should be known, for example Pneumocystis carinii are sub-acute change in the patient infected with HIV while the patient's clinical presentation POH is brutal. The absence of shock is conventional in PCP unless associated co-infections .
The last element is the thoracic high-resolution scanner with millimeter cuts and if necessary cut expiration. It is more sensitive than chest radiography and allows a more accurate description of radiographic abnormalities: frosted glass, condensation, nodules and their associated location or not a ground glass halo, the presence of excavation, the presence of septal line [28 , 29]. Some associations of injuries HRCT can evoke a specific etiology although the specificity is low. Diffuse ground glass association and a quantitative or qualitative lymphocyte depletion is suggestive of infection with Pneumocystis jirovinci . The presence of excavated nodule aplasia exit guide to invasive pulmonary aspergillosis. The presence of septal lines, hypertrophy of the pulmonary veins, and bilateral effusions, is suggestive of pulmonary edema.
The absence of diagnosis is associated with increased mortality. We believe that a systematic approach improves the diagnostic performance to give the right treatment. A probabilistic treatment in the early hours is given according to this strategy. The diagnostic workup should continue in order to confirm or refute the initial assumptions.
Full conference title:
- RICAI 29th (2009)