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High-Frequency Oscillatory Ventilation and Ventilator-Induced Lung Injury: Size Does Matter

Herrmann, Jacob PhD^1,2; Lilitwat, Weerapong MD³; Tawhai, Merryn H. PhD⁴; Kaczka, David W. MD, PhD^1,2,5

¹Department of Biomedical Engineering, University of Iowa, Iowa City, IA.

²Department of Anesthesia, University of Iowa Hospitals and Clinics, Iowa City, IA.

³Department of Pediatrics, University of Iowa Hospitals and Clinics, Iowa City, IA.

⁴Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.

⁵Department of Radiology, University of Iowa Hospitals and Clinics, Iowa City, IA.

Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the U.S. Department of Defense or National Institutes of Health.

Drs. Herrmann and Tawhai performed experiments. Drs. Herrmann and Kaczka prepared figures and drafted article. Drs. Herrmann, Tawhai, and Kaczka conceived and designed research; analyzed data. All authors interpreted results of experiments; edited and revised article; and approved the final version of the article.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (http://journals.lww.com/ccmjournal).

Supported, in part, by grant from the Office of the Assistant Secretary of Defense for Health Affairs through the Peer Reviewed Medical Research Program under Award number W81XWH-16-1-0434, the University of Iowa Hospitals and Clinics Department of Anesthesia, the National Heart, Lung, and Blood Institute Grants R01-HL-112986 and R01-HL-126838, and the University of Auckland Medical Technologies Centre of Research Excellence.

Drs. Herrmann and Kaczka are cofounders and shareholders of OscillaVent, Inc. Dr. Tawhai’s institution received funding from The New Zealand Tertiary Education Commission, for "The Medical Technologies Centre of Research Excellence"; she received funding from the University of Iowa, consulting services for Department of Defense grant; and she received support for article research from The Medical Technologies Centre of Research Excellence. Dr. Kaczka’s institution received funding from Zoll; he received funding from Monitor Mask Inc. for serving on Scientific Advisory Board (stock options); and he received support for article research from the Department of Defense. Dr. Lilitwat disclosed that he does not have any potential conflicts of interest.

For information regarding this article, E-mail: david-kaczka@ uiowa.edu

Critical Care Medicine 48(1):p e66-e73, January 2020. | DOI: 10.1097/CCM.0000000000004073

Abstract

Objectives:

The theoretical basis for minimizing tidal volume during high-frequency oscillatory ventilation may not be appropriate when lung tissue stretch occurs heterogeneously and/or rapidly. The objective of this study was to assess the extent to which increased ventilation heterogeneity may contribute to ventilator-induced lung injury during high-frequency oscillatory ventilation in adults compared with neonates on the basis of lung size, using a computational model of human lungs.

Design:

Computational modeling study.

Setting:

Research laboratory.

Subjects:

High-fidelity, 3D computational models of human lungs, scaled to various sizes representative of neonates, children, and adults, with varying injury severity. All models were generated from one thoracic CT image of a healthy adult male.

Interventions:

Oscillatory ventilation was simulated in each lung model at frequencies ranging from 0.2 to 40 Hz. Sinusoidal flow oscillations were delivered at the airway opening of each model and distributed through the lungs according to regional parenchymal mechanics.

Measurements and Main Results:

Acinar flow heterogeneity was assessed by the coefficient of variation in flow magnitudes across all acini in each model. High-frequency oscillatory ventilation simulations demonstrated increasing heterogeneity of regional parenchymal flow with increasing lung size, with decreasing ratio of deadspace to total acinar volume, and with increasing frequency above lung corner frequency and resonant frequency. Potential for resonant amplification was greatest in injured adult-sized lungs with higher regional quality factors indicating the presence of underdamped lung regions.

Conclusions:

The potential for ventilator-induced lung injury during high-frequency oscillatory ventilation is enhanced at frequencies above lung corner frequency or resonant frequency despite reduced tidal volumes, especially in adults, due to regional amplification of heterogeneous flow. Measurements of corner frequency and resonant frequency should be considered during high-frequency oscillatory ventilation management.

Article Keywords

Keywords
acute respiratory distress syndrome, high-frequency oscillatory ventilation, mechanical ventilation, ventilation heterogeneity, ventilator-induced lung injury

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High-Frequency Oscillatory Ventilation and Ventilator-Induced Lung Injury: Size Does Matter