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- Muders, Thomas, et al.
(författare)
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Individualized Positive End-expiratory Pressure and Regional Gas Exchange in Porcine Lung Injury
- 2020
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Ingår i: Anesthesiology. - : LIPPINCOTT WILLIAMS & WILKINS. - 0003-3022 .- 1528-1175. ; 132:4, s. 808-824
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Tidskriftsartikel (refereegranskat)abstract
- Background: In acute respiratory failure elevated intraabdominal pressure aggravates lung collapse, tidal recruitment, and ventilation inhomogeneity. Low positive end-expiratory pressure (PEEP) may promote lung collapse and intrapulmonary shunting, whereas high PEEP may increase dead space by inspiratory overdistension. The authors hypothesized that an electrical impedance tomography-guided PEEP approach minimizing tidal recruitment improves regional ventilation and perfusion matching when compared to a table-based low PEEP/no recruitment and an oxygenation-guided high PEEP/full recruitment strategy in a hybrid model of lung injury and elevated intraabdominal pressure. Methods: In 15 pigs with oleic acid-induced lung injury intraabdominal pressure was increased by intraabdominal saline infusion. PEEP was set in randomized order: (1) guided by a PEEP/inspired oxygen fraction table, without recruitment maneuver; (2) minimizing tidal recruitment guided by electrical impedance tomography after a recruitment maneuver; and (3) maximizing oxygenation after a recruitment maneuver. Single photon emission computed tomography was used to analyze regional ventilation, perfusion, and aeration. Primary outcome measures were differences in PEEP levels and regional ventilation/perfusion matching. Results: Resulting PEEP levels were different (mean +/- SD) with (1) table PEEP: 11 +/- 3 cm H2O; (2) minimal tidal recruitment PEEP: 22 +/- 3 cm H2O; and (3) maximal oxygenation PEEP: 25 +/- 4 cm H2O; P < 0.001. Table PEEP without recruitment maneuver caused highest lung collapse (28 +/- 11% vs. 5 +/- 5% vs. 4 +/- 4%; P < 0.001), shunt perfusion (3.2 +/- 0.8 l/min vs. 1.0 +/- 0.8 l/min vs. 0.7 +/- 0.6 l/min; P < 0.001) and dead space ventilation (2.9 +/- 1.0 l/min vs. 1.5 +/- 0.7 l/min vs. 1.7 +/- 0.8 l/min; P < 0.001). Although resulting in different PEEP levels, minimal tidal recruitment and maximal oxygenation PEEP, both following a recruitment maneuver, had similar effects on regional ventilation/perfusion matching. Conclusions: When compared to table PEEP without a recruitment maneuver, both minimal tidal recruitment PEEP and maximal oxygenation PEEP following a recruitment maneuver decreased shunting and dead space ventilation, and the effects of minimal tidal recruitment PEEP and maximal oxygenation PEEP were comparable.
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| 2. |
- Muders, Thomas, et al.
(författare)
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Measurement of Electrical Impedance Tomography-Based Regional Ventilation Delay for Individualized Titration of End-Expiratory Pressure
- 2021
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Ingår i: Journal of Clinical Medicine. - : MDPI. - 2077-0383. ; 10:13
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Tidskriftsartikel (refereegranskat)abstract
- 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 (R-2 = 0.87, p < 0.001). Correlations decreased for RVDI values from inflations of 7.5 (R-2 = 0.68, p < 0.001) and 6 (R-2 = 0.42, p < 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.
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