Airway Pressure Release Ventilation Reduces Conducting Airway Micro-Strain in Lung Injury : Journal of the American College of Surgeons

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Original scientific article

Airway Pressure Release Ventilation Reduces Conducting Airway Micro-Strain in Lung Injury

Kollisch-Singule, Michaela MDa; Emr, Bryanna MDa; Smith, Bradford PhDb; Ruiz, Cynthiac; Roy, Shreyas MDa; Meng, Qinghe MDa; Jain, Sumeet MDa; Satalin, Joshua BSa, *; Snyder, Kathya; Ghosh, Auyon MDa; Marx, William H. DO, FACSa; Andrews, Penny RNd; Habashi, Nader MDd; Nieman, Gary F. BAa; Gatto, Louis A. PhDa, c

Author Information

a Department of General Surgery, SUNY Upstate Medical University, Syracuse, NY

b Department of Medicine, University of Vermont, Burlington, VT

c Department of Biological Sciences, SUNY Cortland, Cortland, NY

d R Adams Cowley Shock Trauma Center, Trauma Critical Care Medicine, University of Maryland School of Medicine, Baltimore, MD

*Correspondence address: Joshua Satalin, BS, SUNY Upstate Medical University, 750 E Adams St, Syracuse, NY 13210.

E-mail: [email protected]

Received June 12, 2014; revised July 25, 2014; accepted August 1, 2014.

Disclosure Information: Nothing to disclose.

Support: This work was supported by an AMA Foundation Seed Grant and NIH grant R21 HL092801. The Foundation took no part in the design and conduct of the study, collection, management, analysis, or interpretation of the data.

Presented at American College of Surgeons Committee on Trauma Resident National (March 2014), Upstate NY (November 2013), and Region 2 (December 2013) competitions and awarded First Place for Basic Laboratory Science.

Journal of the American College of Surgeons 219(5):p 968-976, November 2014. | DOI: 10.1016/j.jamcollsurg.2014.09.011

Abstract

BACKGROUND: 

Improper mechanical ventilation can exacerbate acute lung damage, causing a secondary ventilator-induced lung injury (VILI). We hypothesized that VILI can be reduced by modifying specific components of the ventilation waveform (mechanical breath), and we studied the impact of airway pressure release ventilation (APRV) and controlled mandatory ventilation (CMV) on the lung micro-anatomy (alveoli and conducting airways). The distribution of gas during inspiration and expiration and the strain generated during mechanical ventilation in the micro-anatomy (micro-strain) were calculated.

STUDY DESIGN: 

Rats were anesthetized, surgically prepared, and randomized into 1 uninjured control group (n = 2) and 4 groups with lung injury: APRV 75% (n = 2), time at expiration (TLow) set to terminate appropriately at 75% of peak expiratory flow rate (PEFR); APRV 10% (n = 2), TLow set to terminate inappropriately at 10% of PEFR; CMV with PEEP 5 cm H2O (PEEP 5; n = 2); or PEEP 16 cm H2O (PEEP 16; n = 2). Lung injury was induced in the experimental groups by Tween lavage and ventilated with their respective settings. Lungs were fixed at peak inspiration and end expiration for standard histology. Conducting airway and alveolar air space areas were quantified and conducting airway micro-strain was calculated.

RESULTS: 

All lung injury groups redistributed inspired gas away from alveoli into the conducting airways. The APRV 75% minimized gas redistribution and micro-strain in the conducting airways and provided the alveolar air space occupancy most similar to control at both inspiration and expiration.

CONCLUSIONS: 

In an injured lung, APRV 75% maintained micro-anatomic gas distribution similar to that of the normal lung. The lung protection demonstrated in previous studies using APRV 75% may be due to a more homogeneous distribution of gas at the micro-anatomic level as well as a reduction in conducting airway micro-strain.

© 2014 by Lippincott Williams & Wilkins, Inc.

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