Individualizing mechanical ventilation: Titration of driving pressure to pulmonary elastance through Young’s modulus in an acute respiratory distress syndrome animal model

Abstract

Background: Mechanical ventilation increases the risk of lung damage (VILI). Some authors propose that the way to reduce VILI is to find the threshold of driving pressure below which VILI is minimized. In this study, we propose a method to titrate the driving pressure to pulmonary elastance in an acute respiratory distress syndrome model using Young’s modulus and its consequences on ventilatory-induced lung injury. Material and methods: 20 Wister Han male rats were used. After generating an acute respiratory distress syndrome, two groups were studied: a) standard protective mechanical ventilation: 10 rats received 150 minutes of mechanical ventilation with driving pressure = 14 cm H2O, tidal volume < 6mL/kg) and b) individualized mechanical ventilation: 10 rats received 150 minutes of mechanical ventilation with an individualized driving pressure according to their Young’s modulus. In both groups, an individualized PEEP was programmed in the same manner. We analyzed the concentration of IL-6, TNF – α, and IL -1ß in BAL and the acute lung injury score in lung tissue postmortem. Results: Global driving pressure was different between the groups (14 vs 11 cm H2O, p = 0.03). The individualized mechanical ventilation group had lower concentrations in bronchoalveolar lavage of IL-6 (270 vs 155 pg/mL, p = 0.02), TNF – α (292 vs 139 pg/mL, p < 0.01) and IL – 1ß (563 vs 131 pg/mL, p = 0.05). They presented lower proportion of lymphocytes (96% vs 79%, p = 0.05) as well as lower lung injury score (6.0 vs 2.0, p = 0.02). Conclusion: In our model, individualization of DP to pulmonary elastance through Young’s modulus decreases lung inflammation and structural lung injury without a significant impact on oxygenation.