Objectives: The relationship between respiratory mechanical parameters and hemodynamic variables remains unclear. This study was performed to determine whether mean airway pressure and central venous pressure in the first day of mechanical ventilation are associated with patient outcomes.
Design: Retrospective first 24-hour comparison during ICU stay.
Setting: The Department of Critical Care Medicine of Peking Union Medical College Hospital.
Patients: Patients with mechanical ventilation.
Interventions: None.
Measurements and main results: The clinical data of patients who received mechanical ventilation, especially respiratory and hemodynamic data, were collected and analyzed. In terms of the hemodynamic and perfusion data, the nonsurvivors group (177/2,208) had higher heart rate, respiratory rate, central venous pressure, and lactates and a lower perfusion index and P(v-a)CO2 (p < 0.05). In terms of respiratory condition, mean airway pressure, peak airway pressure, positive end-expiratory pressure, driving pressure, and inspiratory time/total respiration time of nonsurvivors were significantly higher, and arterial oxygen pressure and dynamic compliance worsened and were lower than the survivors (p < 0.05). Increased central venous pressure (odds ratio, 1.125; 95% CI, 1.069-1.184; p < 0.001) and elevated mean airway pressure (odds ratio, 1.125; 95% CI, 1.069-1.184; p < 0.001) were independently associated with 28-day mortality. The area under receiver operating characteristic demonstrated that central venous pressure and mean airway pressure were measured at 0.795 (95% CI, 0.654-0.757) and 0.833 (95% CI, 0.608-0.699), respectively. Based on the cutoff of central venous pressure and mean airway pressure, all of the participants were divided into the following groups: low central venous pressure and mean airway pressure, only high central venous pressure or mean airway pressure, or high central venous pressure and mean airway pressure. Post hoc tests showed significant differences among these three groups based on 28-day survival (log rank [Mantel-Cox], 131.931; p < 0.001).
Conclusions: During the first 24 hours of mechanical ventilation, patients with elevated mean airway pressure and elevated central venous pressure had worse outcomes.