Assessment of PaO2/FiO(2) for stratification of patients with moderate and severe acute respiratory distress syndrome
2015 (English)In: BMJ Open, ISSN 2044-6055, E-ISSN 2044-6055, Vol. 5, no 3, e006812Article in journal (Refereed) Published
Objectives: A recent update of the definition of acute respiratory distress syndrome (ARDS) proposed an empirical classification based on ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO(2)) at ARDS onset. Since the proposal did not mandate PaO2/FiO(2) calculation under standardised ventilator settings (SVS), we hypothesised that a stratification based on baseline PaO2/FiO(2) would not provide accurate assessment of lung injury severity. Design: A prospective, multicentre, observational study. Setting: A network of teaching hospitals. Participants: 478 patients with eligible criteria for moderate (100<PaO2/FiO(2)<= 200) and severe (PaO2/FiO(2)<= 100) ARDS and followed until hospital discharge. Interventions: We examined physiological and ventilator parameters in association with the PaO2/FiO(2) at ARDS onset, after 24 h of usual care and at 24 h under a SVS. At 24 h, patients were reclassified as severe, moderate, mild (200<PaO2/FiO(2)<= 300) ARDS and non-ARDS (PaO2/FiO(2)>300). Primary and secondary outcomes: Group severity and hospital mortality. Results: At ARDS onset, 173 patients had a PaO2/FiO(2)<= 100 but only 38.7% met criteria for severe ARDS at 24 h under SVS. When assessed under SVS, 61.3% of patients with severe ARDS were reclassified as moderate, mild and non-ARDS, while lung severity and hospital mortality changed markedly with every PaO2/FiO(2) category (p<0.000001). Our model of risk stratification outperformed the stratification using baseline PaO2/FiO(2) and non-standardised PaO2/FiO(2) at 24 h, when analysed by the predictive receiver operating characteristic (ROC) curve: area under the ROC curve for stratification at baseline was 0.583 (95% CI 0.525 to 0.636), 0.605 (95% CI 0.552 to 0.658) at 24 h without SVS and 0.693 (95% CI 0.645 to 0.742) at 24 h under SVS (p<0.000001). Conclusions: Our findings support the need for patient assessment under SVS at 24 h after ARDS onset to assess disease severity, and have implications for the diagnosis and management of ARDS patients.
Place, publisher, year, edition, pages
2015. Vol. 5, no 3, e006812
Respiratory Medicine and Allergy
IdentifiersURN: urn:nbn:se:uu:diva-267586DOI: 10.1136/bmjopen-2014-006812ISI: 000363458200056PubMedID: 25818272OAI: oai:DiVA.org:uu-267586DiVA: diva2:873716