Non Invasive Positive Pressure Ventilation (NIPPV) is the accepted initial treatment for exacerbation of chronic obstructive lung disease and cardiogenic pulmonary edema. Its role in Acute Lung Injury (ALI) is controversial. We sought to assess the outcome of ALI initially treated with NIPPV and to identify specific risk factors for NIPPV failure in this patient population.
In this observational cohort study,consecutive patients with ALI initially treated with NIPPV were identified. ALI was defined according to standard American European Consensus Conference Definition. Patients with do not resuscitate orders were excluded. NIPPV failure was defined as the need to intubation or death while on NIPPV. Data on demographics, APACHE III scores, degree of hypoxemia (PaO2/FIO2), presence of shock, sepsis, aspiration, transfusion, metabolic acidosis, time to intubation, as well as NIPPV parameters (tidal volume, minute volume, inspiratory and expiratory pressure) were recorded. Univariate and multivariate regression analysis was performed to identify risk factors for NIPPV failure.
79 patients met the inclusion criteria. 23 were excluded because of do not resuscitate order and 2 denied research authorization. 34 of the remaining 54 patients (62.9%) had a primary diagnosis of pneumonia. 38 (70.3%) patients failed NIPPV, including all 19 patients with shock. ALI patients successfully treated with NIPPV had lower Apache-3 scores (55.5 vs 81.5; p=0.004), were less likely to have metabolic acidosis (base deficit: 0.52 vs -4.01; p=0.017) and severe hypoxemia (PaO2/FIO2: 147 vs 112; p=0.020). Multivariate logistic regression analysis identified higher base deficit (p= 0.04) and lower PaO2/FIO2 ratio (p=0.008) but not APACHE III scores (p=0.105) as significant predictors of NIPPV failure. In patients who failed NIPPV the observed mortality was higher than APACHE predicted mortality (68.4% vs 38.6 %).
The presence of septic shock, low PaO2/FIO2 ratio and metabolic acidosis in patients with Acute Lung Injury predicts failure of NIPPV .
NIPPV should not be used in patients with Acute Lung Injury who have shock, metabolic acidosis or profound hypoxemia.
Sameer Rana, None.