Influence of driving pressure and tidal volume on survival of unselected patients requiring mechanical ventilation: a prospective longitudinal study in the ICUs of a quaternary academic medical centerin Brazil

<jats:p>Objective: To evaluate the association of driving pressure (ΔP) and VT with survival in unselected patients on mechanical ventilation (MV) in a quaternary care hospital in Brazil, as well as whether the initial behavior of ΔP influenced the number of ventilatorfree days. Methods: This was a single-center prospective cohort study of hospitalized adults across 13 ICUs of an academic medical center in the city of São Paulo, Brazil. We analyzed the first instance of invasive MV ≥ 24 h. Patients were followed for up to 60 days after ICU admission. We used Cox regression to analyze patient survival in relation to ΔP and VT on the first day of MV. The number of ventilator-free days was compared between patients in whom ΔP decreased on the first three days of MV and those in whom ΔP increased or remained stable. Results: A total of 231 patients were evaluated. Of those, 57% were male. The mean age was 55 ± 18 years. The mean Simplified Acute Physiology Score III was 61 ± 17. The median Charlson Comorbidity Index was 3 [IQR, 1-4]. Survival analysis showed that neither ΔP (relative risk = 1.04; 95% CI, 0.08-0.99; p = 0.09) nor VT (relative risk = 0.98; 95% CI, 0.90-1.07; p = 0.66) on the first day of MV affected survival. Disease severity (Simplified Acute Physiology Score III; p &lt; 0.005) and comorbidities (Charlson Comorbidity Index; p &lt; 0.005) were crucial factors for mortality. Conclusions: In our cohort of mechanically ventilated patients with high disease severity and comorbidity burden, neither ΔP nor VT on the first day of MV was associated with survival. No ventilation variable predicted survival, which was primarily determined by disease severity and comorbidities. Changes in ΔP over the first three days were not associated with differences in the number of ventilator-free days.</jats:p>