Driving Pressure and Hospital Mortality in Patients Without ARDS: A Cohort Study.

BACKGROUND: Driving pressure (ΔP) is associated with mortality in patients with ARDS and with pulmonary complications in patients undergoing general anesthesia. Whether ΔP is associated with outcomes of patients without ARDS who undergo ventilation in the ICU is unknown. Our objective was to determine the independent association between ΔP and outcomes in mechanically ventilated patients without ARDS on day 1 of mechanical ventilation. METHODS: This was a retrospective analysis of a cohort of 622 mechanically ventilated adult patients without ARDS on day 1 of mechanical ventilation from five ICUs in a tertiary center in the United States. The primary outcome was hospital mortality. The presence of ARDS was determined using the minimum daily Pao2 to Fio2 (PF) ratio and an automated text search of chest radiography reports. The data set was validated by first testing the model in 543 patients with ARDS. RESULTS: In patients without ARDS on day 1 of mechanical ventilation, ΔP was not independently associated with hospital mortality (OR, 1.01; 95% CI, 0.97-1.05). The results of the primary analysis were confirmed in a series of preplanned sensitivity analyses. CONCLUSIONS: In this cohort of patients without ARDS on day 1 of mechanical ventilation and within the limits of ventilatory settings normally used by clinicians, ΔP was not associated with hospital mortality. This study also confirms the association between ΔP and mortality in patients with ARDS not enrolled in a trial and in hypoxemic patients without ARDS.

The use of the pulse oximetric saturation to fraction of inspired oxygen ratio in an automated acute respiratory distress syndrome screening tool.

PURPOSE: To determine the relationship between the pulse oximetric saturation to fraction of inspired oxygen (SF) ratio and the arterial partial pressure of oxygen to the fraction of inspired oxygen (PF) ratio, and to assess the usefulness of the SF ratio in an automated acute respiratory distress syndrome (ARDS) screening tool. MATERIAL AND METHODS: This was a retrospective cohort study using the Multiparameter Intelligent Monitoring in Intensive Care II database. The relationship was derived and validated in all patients ventilated for at least 24 hours. RESULTS: The total data set included 7544 paired measurements from 3767 intensive care unit admissions. The correlation between SF ratio and PF ratio in the whole data set was good (Spearman ρ = 0.72, P < .001). An automated ARDS diagnostic tool using the derived SF cutoff had excellent agreement with the same tool using the PF ratio of 300 (κ = 0.87). CONCLUSION: The SF ratio may be an adequate substitute for the PF ratio in an automated ARDS screening tool.