For a study, researchers sought to determine the relationship between VDPhys/VT and coagulation activation and outcomes. Patients diagnosed with COVID-19 pneumonia and in need of invasive mechanical ventilation and volumetric capnography monitoring were enrolled in the study by the designers. Measurements were taken for the first 24 hours the patient received mechanical ventilation. The probability of being released on day 28 while still alive served as the primary indicator of success. About 60 patients were enrolled, with 25 (42%) having a high VDPhys/VT (>57%). Patients with high versus low VDPhys/VT had higher APACHE II scores (10[8-13] vs. 8[6-9] points, P=0.002), lower static compliance of the respiratory system (35[24–46] mL/cm H2O vs. 42[37–45] mL/cmH2O, P=0.005), and higher D-dimer levels (1246[1050–1594] ng FEU/mL vs. 792[538–1159] ng FEU/mL, P=0.001), without differences in P/F ratio (157[112–226] vs. 168[136–226], P=0.719).  In addition, D-dimer levels were correlated with VDPhys/VT (r=0.530, P<0.001), but not with P/F (r=−0.103, P=0.433). Patients with high VDPhys/VT had a lower likelihood of being discharged alive on day 28 (32% vs. 71%, aHR = 3.393[1.161–9.915], P=0.026). In critically ill COVID-19 patients, a higher VDPhys/VT ratio was associated with elevated D-dimer concentrations and a decreased likelihood of discharge. A dichotomous VDPhys/VT could help identify a subgroup of high-risk patients that the P/F ratio overlooks.

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