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A5839 - Fluid Challenge Induces Transient Airway Wall Edema Visualized Via Optical Coherence Tomography
Author Block: J. Thiboutot1, W. Scott2, H. Park2, X. Li2, L. B. Yarmus3, W. Mitzner4, R. H. Brown5; 1Pulmonary and Critical Care Medicine, Johns Hopkins University, Baltimore, MD, United States, 2Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States, 3Pulmonary and Critical Care Medicine, Johns Hopkins University, Clarksville, MD, United States, 4Respiratory Biology and Lung Disease, Johns Hopkins Bloomberg Sch of Public Hlth, Baltimore, MD, United States, 5Department of Anesthesiology and Critical Care Medicine, Department of Medicine, Johns Hopkins Sch of Public Health, Baltimore, MD, United States.
Background: Pulmonary alveolar filling is a common manifestation of many pathologic processes, most commonly manifesting as pulmonary edema. Physiologic fluid overload states are known to manifest with alveolar interstitial thickening and fluid accumulation within the alveoli themselves, however the extent to which interstitial fluid can accumulate and resolve over short periods of time in unclear.
Methods: In a healthy sheep model, following endotracheal intubation a fourth-generation airway in the right middle lobe was selected for imaging. Using a custom engineered 800nm endoscopic optical coherence tomography (OCT) system, baseline imaging was performed of the airway. A rapid peripheral infusion of 1 liter of 0.9% normal saline was performed and OCT imaging of the same selected airway was immediately performed. This process was repeated until a total of 3 liters were infused. Imaging was then performed one hour after the final infusion to assess recovery.
Results: With each infusion of 1 liter of normal saline, the airway wall thickness was increased. Additionally, with each subsequent infusion, progressive airway wall thickening was identified. This demonstrated a dose response of wall thickening with each infusion. At one hour following the third and final infusion, OCT imaging showed a decrease in airway wall thickness from imaging captured immediately following the third and final fluid challenge.
Discussion: This study demonstrates that airway wall thickening occurs with acute volume challenges in a healthy animal model. This airway wall thickening likely represents transient edema formation brought on by interstitial volume expansion that is progressively increased by further fluid challenge. The downtrend in wall thickness at 1 hour following the final fluid challenge indicates this edema can be quickly mobilized and is reversible in a healthy host. This also demonstrates OCT’s ability to assess acute, transient changes in the airway wall permitting the study of diseased states (such as congestive heart failure) and to better elucidate their pathologic consequences. This lays the groundwork for OCT’s transition to human studies.