Publication date: Jun 01, 2026
Ventilatory ratio (VR) could be a useful marker of COVID-19 acute respiratory distress syndrome (ARDS) worsening, since its value has been shown to correlate with dead space and severity of non-COVID-19 ARDS. In this study, we sought to: 1) compare VR to the estimated intrapulmonary shunt and the Pao2/Fio2 ratio for the association with the risk of intubation and 2) define the best VR threshold to discriminate between intubated patients and nonintubated patients. Multicenter, prospective experimental study. ICUs from University and General Hospitals. Patients with moderate-to-severe COVID-19 ARDS. We conducted standardized continuous positive airway pressure sessions with an Fio2 of 100% and positive end-expiratory pressure of 5 cm H2O to calculate the Pao2/Fio2 ratio, the estimated intrapulmonary shunt (indexed on cardiac output), and VR. These sessions were repeated until intubation or ICU discharge. A time-dependent joint multivariable model was performed. Fifty-two patients were included, 25 of whom required intubation (48%). Among studied variables including the Pao2/Fio2 ratio and the estimated intrapulmonary shunt, VR was most associated with the longitudinal risk of intubation with a hazard ratio (HR, 3. 30; 97. 5% CI, 1. 42-8. 91; p = 0. 001) compare to the Pao2/Fio2 ratio with HR (0. 98; 97. 5% CI, 0. 97-0. 99; p = 0. 002) and the estimated intrapulmonary shunt with HR (2. 31; 97. 5% CI, 0. 37-24. 01; p = 0. 394). The best VR threshold values were identified at day 1 (VR = 2. 1, sensitivity, 85. 7%; specificity, 60. 1%; area under the receiver operating characteristic curve [AUC] = 0. 810), day 3 (VR = 2. 3; sensitivity, 92. 0%; specificity, 91. 2%; AUC = 0. 973), and day 5 (VR = 2; sensitivity, 92%; specificity, 97%; AUC = 0. 979) to discriminate intubated and nonintubated patients. The study provides valuable insights into COVID-19 ARDS, highlighting VR as a reliable and objective predictor of intubation. Increased VR could be a critical marker of lung injury progression in patients with ARDS.