Use of VO2 vs Static Compliance for Determination of Optimal PEEP in ARDS Patients

Abstract
Background: Protective ventilation strategies using low tidal volume, limiting plateau pressure and manipulating FiO2- PEEP combination to reach target oxygenation are standard for treatment of ARDS patients. However, the appropriate PEEP level for ventilating such individuals has not been established.
Aim of Study: The study investigated the effect of VCO2 guided PEEP vs static compliance guided PEEP on oxygena-tion, CO2 elimination, alveolar ventilation and static compli-ance in ARDS patients.
Patients and Methods: This prospective randomized controlled study was conducted at a tertiary university hospital ICU including sixty mechanically ventilated ARDS patients. Patients were randomized between two groups; Group A, where PEEP was titrated using static compliance and Group B, where PEEP was titrated using VCO2, once it failed to recover to baseline, the preceding PEEP value was considered optimum.
Results: Both groups received comparable values of PEEP applied (p£0.499). This resulted in a significant increase in SpO2, PaO2, PaO2/FiO2, VA and static compliance from baseline (p£0.001 in both groups), with no significant differ-ence between the two groups. Mean and standard deviation of VCO2 showed a significant increase from baseline (221.37±44.582 vs 225.10±46.42; p£0.004) in Group B with no significant difference between two groups. Two cases in Group A had a decrease in VCO2 from baseline and one showed both a decrease in VCO2 from baseline and MAP below 65mmHg. Despite that mean and standard deviation of MAP doesn't significantly change from baseline (90.00± 17.76 vs 89.50±17.57; p£0.5006 and 86.83±16.47 vs 85.27± 17.43 p£0.1577) in both groups, and showed no significant difference between the two groups.
Conclusion: Using VCO2 to determine optimum PEEP associated with comparable improvement in oxygenation and lung compliance, while resulting in a significant improvement in CO2 elimination compared with optimum PEEP determined by static compliance in ARDS patients. It was, also, associated with no complication in terms of hemodynamic stability in contrast to optimum PEEP determined by static compliance which was associated with incidence of hemodynamic insta-bility.