ARDS may occur after either septic or nonseptic injuries. Sepsis is the major cause of ARDS, but little is known about the differences between sepsis-related and non-sepsis-related ARDS.
A total of 2,786 patients with ARDS-predisposing conditions were enrolled consecutively into a prospective cohort, of which 736 patients developed ARDS. We defined sepsis-related ARDS as ARDS developing in patients with sepsis and non-sepsis-related ARDS as ARDS developing after nonseptic injuries, such as trauma, aspiration, and multiple transfusions. Patients with both septic and nonseptic risks were excluded from analysis.
Compared with patients with non-sepsis-related ARDS (n = 62), patients with sepsis-related ARDS (n = 524) were more likely to be women and to have diabetes, less likely to have preceding surgery, and had longer pre-ICU hospital stays and higher APACHE III (Acute Physiology and Chronic Health Evaluation III) scores (median, 78 vs 65, P < .0001). There were no differences in lung injury score, blood pH, Pao2/Fio2 ratio, and Paco2 on ARDS diagnosis. However, patients with sepsis-related ARDS had significantly lower Pao2/Fio2 ratios than patients with non-sepsis-related ARDS patients on ARDS day 3 (P = .018), day 7 (P = .004), and day 14 (P = .004) (repeated-measures analysis, P = .011). Compared with patients with non-sepsis-related ARDS, those with sepsis-related had a higher 60-day mortality (38.2% vs 22.6%; P = .016), a lower successful extubation rate (53.6% vs 72.6%; P = .005), and fewer ICU-free days (P = .0001) and ventilator-free days (P = .003). In multivariate analysis, age, APACHE III score, liver cirrhosis, metastatic cancer, admission serum bilirubin and glucose levels, and treatment with activated protein C were independently associated with 60-day ARDS mortality. After adjustment, sepsis-related ARDS was no longer associated with higher 60-day mortality (hazard ratio, 1.26; 95% CI, 0.71-2.22).
Sepsis-related ARDS has a higher overall disease severity, poorer recovery from lung injury, lower successful extubation rate, and higher mortality than non-sepsis-related ARDS. Worse clinical outcomes in sepsis-related ARDS appear to be driven by disease severity and comorbidities.