Measurement of Electrical Impedance Tomography-Based Regional Ventilation Delay for Individualized Titration of End-Expiratory Pressure

• Main Authors: Thomas Muders, Benjamin Hentze, Stefan Kreyer, Karin Henriette Wodack, Steffen Leonhardt, Göran Hedenstierna, Hermann Wrigge, Christian Putensen
• Format: Article
• Language: English
• Published: MDPI AG 2021-06-01
• Series: Journal of Clinical Medicine
• Subjects: acute respiratory distress syndrome; positive end-expiratory pressure; individualized therapy; electrical impedance tomography; monitoring; functional imaging
• Online Access: https://www.mdpi.com/2077-0383/10/13/2933

Rationale: Individualized positive end-expiratory pressure (PEEP) titration might be beneficial in preventing tidal recruitment. To detect tidal recruitment by electrical impedance tomography (EIT), the time disparity between the regional ventilation curves (regional ventilation delay inhomogeneity [RVDI]) can be measured during controlled mechanical ventilation when applying a slow inflation of 12 mL/kg of body weight (BW). However, repeated large slow inflations may result in high end-inspiratory pressure (P_EI), which might limit the clinical applicability of this method. We hypothesized that PEEP levels that minimize tidal recruitment can also be derived from EIT-based RVDI through the use of reduced slow inflation volumes. Methods: Decremental PEEP trials were performed in 15 lung-injured pigs. The PEEP level that minimized tidal recruitment was estimated from EIT-based RVDI measurement during slow inflations of 12, 9, 7.5, or 6 mL/kg BW. We compared RVDI and P_EI values resulting from different slow inflation volumes and estimated individualized PEEP levels. Results: RVDI values from slow inflations of 12 and 9 mL/kg BW showed excellent linear correlation (<i>R</i>² = 0.87, <i>p</i> < 0.001). Correlations decreased for RVDI values from inflations of 7.5 (<i>R</i>² = 0.68, <i>p</i> < 0.001) and 6 (<i>R</i>² = 0.42, <i>p</i> < 0.001) mL/kg BW. Individualized PEEP levels estimated from 12 and 9 mL/kg BW were comparable (bias −0.3 cm H₂O ± 1.2 cm H₂O). Bias and scatter increased with further reduction in slow inflation volumes (for 7.5 mL/kg BW, bias 0 ± 3.2 cm H₂O; for 6 mL/kg BW, bias 1.2 ± 4.0 cm H₂O). P_EI resulting from 9 mL/kg BW inflations were comparable with P_EI during regular tidal volumes. Conclusions: PEEP titration to minimize tidal recruitment can be individualized according to EIT-based measurement of the time disparity of regional ventilation courses during slow inflations with low inflation volumes_. This sufficiently decreases P_EI and may reduce potential clinical risks.