Open lung biopsy in nonresolving ARDS frequently identifies diffuse alveolar damage regardless of the severity stage and may have implications for patient management.

PURPOSE: The aim of the present study was to assess the rate of diffuse alveolar damage (DAD) on open lung biopsy (OLB) performed in the ICU for nonresolving ARDS. METHODS: A single-center retrospective study of patients meeting the Berlin definition criteria for ARDS who had undergone OLB for nonresolving ARDS. Patients were classified into mild, moderate and severe ARDS categories and according to the presence or absence of DAD on the OLB. The ARDS categories were assessed at baseline and at the time of the OLB. The OLBs were reviewed by two pathologists blinded to the ARDS classification. The primary endpoint was the rate of DAD according to the ARDS stage in the patients with nonresolving ARDS who had OLB. The secondary endpoint was the ability of DAD to predict ARDS among all the patients who had OLB. The same clinico-histopathological confrontation was cross validated in another ICU. RESULTS: From January 1998 to August 2013, 113 patients underwent OLB for acute hypoxemic respiratory failure, 83 of whom met the inclusion criteria for ARDS. At the time the OLB was performed, 11 of these patients had mild, 56 moderate, and 16 severe ARDS, respectively. The median (1st-3rd quartiles) time to OLB was 13 (10-18) and 9 (6-14) days from the onset of respiratory symptoms and from ARDS onset, respectively, with no statistical difference between the three ARDS groups. DAD was found in 48 (58 %) patients with ARDS, 4 (36 %) in the mild, 33 (59 %) in the moderate, and 11 (69 %) in the severe stage (P = 0.23). For the 113 patients who underwent OLB, the sensitivity and specificity of DAD to the Berlin definition was 0.58 (0.46-0.69) and 0.73 (0.54-0.88), respectively. Similar results were found in the other ICU. CONCLUSIONS: DAD is present in the majority of patients with nonresolving ARDs and its frequency is no different across the three ARDS stages. On this basis, the systematic use of steroids in nonresolving ARDS is not recommended.

Does gas exchange response to prone position predict mortality in hypoxemic acute respiratory failure?

OBJECTIVE: To determine whether gas exchange response to a first prone position session can predict patient outcome in hypoxemic acute respiratory failure. METHODS: Data from a previous multicenter randomized controlled trial were retrospectively analyzed for relationship between PaO(2)/FIO(2) ratio and PaCO(2) changes during the first 8-h prone position session to day 28 mortality rate; 370 prone position sessions were analyzed. Arterial blood gas was measured in supine position before proning and in prone position at the end of the session. Gas exchange improvement was defined as increase in the PaO(2)/FIO(2) ratio of more than 20% (PaO(2)R) or decrease in PaCO(2) of more than 1 mmHg (PaCO(2)R). MAIN RESULTS: The 28-day mortality rate was 26.5% in PaO(2)R-PaCO(2)R, 31.7% in PaO(2)R-PaCO(2)NR, 38.9% in PaO(2)NR-PaCO(2)R, and 43% in PaO(2)NR-PaCO(2)NR (log-rank 14.02, p = 0.003). In a Cox proportional hazards model the gas exchange response was a significant predictor to patient outcome with a 82.5% increase in risk of death in the case of PaO(2)NR-PaCO(2)R or PaO(2)NR-PaCO(2)NR, relative to the gas exchange improvement response (odds ratio 1.825). However, after adjusting for the difference in oxygenation between day 2 and day 1 the gas exchange response does no longer reach significance. CONCLUSION: In patients with hypoxemic acute respiratory failure initial improvement in gas exchange in the first PP session was associated with a better outcome, but this association disappeared when the change in oxygenation from day 1 to day 2 was taken into account, suggesting that underlying illness was the most important predictor of mortality in this patient population.