Critical Care Medicine  |   April 2020
Individualized Positive End-expiratory Pressure and Regional Gas Exchange in Porcine Lung Injury
Author Notes
  • From the Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Germany (T.Muders, H.L., J.Z., S.K., C.P.); the Department of Anesthesiology and Intensive Care Medicine, University of Schleswig Holstein, Campus Lübeck, Germany (T.Meier); the Department of Anesthesiology and Intensive Care Medicine, University of Leipzig, Germany (A.W.R.); the Federal Institute for Drugs and Medical Devices/Bundesinstitut für Arzneimittel und Medizinprodukte (BfArM), Bonn, Germany (J.Z.); the Philips Chair for Medical Information Technology, Helmholtz-Institute for Biomedical Engineering, RWTH Aachen University, Aachen, Germany (R.P., S.L.); the Department of Medical Physics University Hospital, Uppsala, Sweden (E.M.); the Department of Medical Sciences, Clinical Physiology, Uppsala University, Sweden (G.H.); the Department of Anesthesiology, Intensive Care and Emergency Medicine, Pain Therapy; Bergmannstrost Hospital Halle, Halle, Germany (H.W.).
  • Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).
    Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).×
  • Some of the results of this work have been previously presented as an abstract at the American Thoracic Society International Conference in San Diego, California, on May 15 to 22, 2009; at the American Thoracic Society International Conference in New Orleans, Louisiana, on May 14 to 19, 2010; and at the 23rd Annual European Society of Intensive Care Medicine (ESICM) Congress in Barcelona, Spain, on October 9 to 13, 2010.
    Some of the results of this work have been previously presented as an abstract at the American Thoracic Society International Conference in San Diego, California, on May 15 to 22, 2009; at the American Thoracic Society International Conference in New Orleans, Louisiana, on May 14 to 19, 2010; and at the 23rd Annual European Society of Intensive Care Medicine (ESICM) Congress in Barcelona, Spain, on October 9 to 13, 2010.×
  • Submitted for publication December 11, 2018. Accepted for publication December 20, 2019. Published online first on February 21, 2020.
    Submitted for publication December 11, 2018. Accepted for publication December 20, 2019. Published online first on February 21, 2020.×
  • Address correspondence to Dr. Muders: Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, D - 53105 Bonn, Germany. t.muders@uni-bonn.de. Information on purchasing reprints may be found at www.anesthesiology.org or on the masthead page at the beginning of this issue. Anesthesiology’s articles are made freely accessible to all readers, for personal use only, 6 months from the cover date of the issue.
Article Information
Critical Care Medicine / Basic Science / Critical Care / Respiratory System
Critical Care Medicine   |   April 2020
Individualized Positive End-expiratory Pressure and Regional Gas Exchange in Porcine Lung Injury
Anesthesiology 4 2020, Vol.132, 808-824. doi:https://doi.org/10.1097/ALN.0000000000003151
Anesthesiology 4 2020, Vol.132, 808-824. doi:https://doi.org/10.1097/ALN.0000000000003151
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.

Editor’s Perspective:

What We Already Know about This Topic:

  • In acute lung injury, the optimal positive end-expiratory pressure (PEEP) strategy for mechanical ventilation is not known.

What This Article Tells Us That Is New:

  • In a porcine model of induced acute lung injury, with increased abdominal pressure caused by intraperitoneal saline infusion, using a crossover design, tracheostomized animals were ventilated using: (1) positive end-expiratory pressure (PEEP) table–based low PEEP without lung recruitment; (2) minimal tidal recruitment PEEP guided by electrical impedance tomography with recruitment; and (3) maximal oxygenation PEEP with recruitment.

  • Using a PEEP table and no recruitment, compared with recruitment and either minimal tidal recruitment PEEP or maximal oxygenation PEEP, resulted in less delivered PEEP, and more lung collapse and regional ventilation/perfusion mismatch. The latter two methods had comparable results.