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ABSTRACT: Rationale and objectives
Pulmonary atelectasis presumably promotes and facilitates lung injury. However, data are limited on its direct and remote relation to inflammation. We aimed to assess regional 2-deoxy-2-[18F]-fluoro-D-glucose (18F-FDG) kinetics representative of inflammation in atelectatic and normally aerated regions in models of early lung injury.Materials and methods
We studied supine sheep in four groups: Permissive Atelectasis (n = 6)-16 hours protective tidal volume (VT) and zero positive end-expiratory pressure; Mild (n = 5) and Moderate Endotoxemia (n = 6)- 20-24 hours protective ventilation and intravenous lipopolysaccharide (Mild = 2.5 and Moderate = 10.0 ng/kg/min), and Surfactant Depletion (n = 6)-saline lung lavage and 4 hours high VT. Measurements performed immediately after anesthesia induction served as controls (n = 8). Atelectasis was defined as regions of gas fraction <0.1 in transmission or computed tomography scans. 18F-FDG kinetics measured with positron emission tomography were analyzed with a three-compartment model.Results
18F-FDG net uptake rate in atelectatic tissue was larger during Moderate Endotoxemia (0.0092 ± 0.0019/min) than controls (0.0051 ± 0.0014/min, p = 0.01). 18F-FDG phosphorylation rate in atelectatic tissue was larger in both endotoxemia groups (0.0287 ± 0.0075/min) than controls (0.0198 ± 0.0039/min, p = 0.05) while the 18F-FDG volume of distribution was not significantly different among groups. Additionally, normally aerated regions showed larger 18F-FDG uptake during Permissive Atelectasis (0.0031 ± 0.0005/min, p < 0.01), Mild (0.0028 ± 0.0006/min, p = 0.04), and Moderate Endotoxemia (0.0039 ± 0.0005/min, p < 0.01) than controls (0.0020 ± 0.0003/min).Conclusion
Atelectatic regions present increased metabolic activation during moderate endotoxemia mostly due to increased 18F-FDG phosphorylation, indicative of increased cellular metabolic activation. Increased 18F-FDG uptake in normally aerated regions during permissive atelectasis suggests an injurious remote effect of atelectasis even with protective tidal volumes.
SUBMITTER: Hinoshita T
PROVIDER: S-EPMC7486228 | biostudies-literature | 2020 Dec
REPOSITORIES: biostudies-literature
Academic radiology 20200312 12
<h4>Rationale and objectives</h4>Pulmonary atelectasis presumably promotes and facilitates lung injury. However, data are limited on its direct and remote relation to inflammation. We aimed to assess regional 2-deoxy-2-[<sup>18</sup>F]-fluoro-D-glucose (<sup>18</sup>F-FDG) kinetics representative of inflammation in atelectatic and normally aerated regions in models of early lung injury.<h4>Materials and methods</h4>We studied supine sheep in four groups: Permissive Atelectasis (n = 6)-16 hours p ...[more]