Non-invasive ventilation in patients with hematological malignancies: the saga continues, but where is the finale?

Excerpt

Acute respiratory failure (ARF) is a dreaded and often fatal event in the course of hematological illness, occurring as a manifestation of the malignant disease process or treatment toxicity, or as a consequence of infection. Even though major advances have been achieved in the care of the critically ill hematological patient over the last 2 decades, acute respiratory failure requiring intubation and mechanical ventilation still has an associated mortality of 50–70% [1‐5]. As such, strategies aiming to avoid intubation may have more potential to positively impact survival here than further improvements or refinements of the care of the invasively ventilated patient. Since noninvasive mechanical ventilation (NIV) has been shown to effectively reverse ARF without the need for intubation, and consequently improve survival, in that other category of patients with poor prognosis once intubated, i.e., the patient with chronic obstructive pulmonary disease (COPD) exacerbation, noninvasive modes of mechanical ventilatory support have been increasingly used in hematological patients with ARF. Two small interventional trials [6, 7] randomizing immunocompromized patients (including hematological patients in one study [7]) with hypoxemia and diffuse pulmonary infiltrates between therapy with NIV and supportive oxygen only found reduced rates of intubation and better survival in the NIV-treated arm, and thus founded the main scientific rationale for the use of NIV in hematological patients with ARF. Observational studies provided more conflicting results, as some of these found an association between better survival and the use of NIV as compared with invasive ventilation [2], while others identified no such protective effect of NIV [4, 5]. While these observational data could not prove a beneficial effect of NIV (or a lack thereof), they provided additional insights into the relationships among the ventilator mode used, the etiology underlying ARF, and the patient outcome, which are more complex in hematological patients than for instance in COPD patients. First, the disease process leading to ARF, and more precisely the reversibility of it, has a major impact on mortality, and may act as an important confounder in the association between ventilator mode and outcome, as not all of these underlying etiologies may be appropriate for NIV [3‐5]. Second, the optimal timing of starting NIV as well as aborting a trial of NIV is likely critical to its potential to improve outcome: delaying NIV has been identified as an important risk factor for NIV failure [8], and conversion of NIV to invasive ventilation itself has been shown to be associated with very high rates of mortality [3‐5, 8]. …