Use of lung recruitment and individualized PEEP setting in the ventilatory management of C-ARDS

Introduction: Lung protective ventilation is the cornerstone of the ventilatory management of COVID-29 related ARDS (C-ARDS) Lung recruitment maneuvers (RM) and their related optimum PEEP setting are frequently used as adjuvant interventions However, as lung collapse does not seem to be an important pathophysiologic component, these interventions may be less effective in C-ARDS Objectives: To study the role of RM and individualized PEEP settings as adjuvant lung protective interventions in the management of ventilated C-ARDS patients We specifically analyzed the obtained PEEP levels and the effects on lung mechanics Methods: Retrospective analysis of all registered RM followed by a decremental PEEP titration performed in C-ARDS patients performed during the peak of the COVID pandemia in a teaching tertiary hospital ICU Maneuvers were registered either by electrical impedance tomography (EIT-Enlight 1800,Timpel) or a sequential automated recruitment maneuver (Servo-u, Maquet CC) We compared individual PEEP levels determined during a decremental PEEP trial by global (Cg) or regional (Creg) compliance Cg was defined by the maximal global compliance and Creg by the point of minimum overdistension and collapse as measured by EIT(1) We also analyzed differences in PEEP individualization between supine and prone positioning After checking for normality of the data distributions means were compared using t-test for independent variables Results: The analysis includes a total of 90 registered RM-PEEP titrations (60 in supine and 30 in prone) in 19 patients (4 6 RM per patient) Recruitment pressures (mean ± SD) were 48 ± 4/33 ± 4 cmH2O (inspiratory pressure/PEEP) Obtained individualized PEEP levels were 10 5±2 2 cmH2O for Cg and 8 8 ± 2,3 cmH2O for Creg (p < 0 05) Respiratory system compliance, plateau and driving pressures improved after RM and PEEP setting from 37 1 ± 14 2 to 42 5 ± 13 8 ml/ cmH2O p < 0 001;24 9 ± 3 6 to 22 7 ± 3 1 cmH2O p < 0 001 and 13 8±3 1 to 11 5 ± 2 8 cmH2O p < 0 01, respectively There were no differences between supine and prone position in individualized PEEP levels (Cg 10 6 ± 3 2 vs 10 2 ± 3 33 and Creg 8 9 ± 3 1 vs 8 6 ± 3 6) and respiratory system compliance was better in supine than in prone (41 9 ± 13 8 vs 42 8 ± 16 8 p < 0 05) respectively At the determined Cg and Creg PEEP levels lung protective ventilation resulted in a percentage overdistension of 10 ± 7 9 and 4 5 ± 3 4% and collapse of y 3 4±3 6 and 4 5±2,5% of the total lung respectively as measured by EIT Small changes in the applied PEEP levels resulted in important changes in the percentage overdistension and/or collapse Conclusion: Lung recruitment and individualized PEEP titration was an effective adjuvant lung protective intervention It allowed to adjust and minimize PEEP in each individual patient and at different stages during the evolution The individualized PEEP levels according to Creg were lower with less overdistension but more collapse than the ones according to Cg