In vivo assessment of airway wall compliance during inhalation injury response using anatomical optical coherence elastography.

Significance: Inhalation injury, a critical complication in patients with severe burns, contributes substantially to morbidity and mortality. Current diagnostic practices suffer from subjectivity and lack quantitative metrics. Enhanced diagnostic accuracy is imperative for improving treatment outcomes.

Aim: Our objective was to develop normalized cross-sectional compliance (nCsC) of the airway wall, as measured by anatomical optical coherence tomography (aOCT), to reflect the severity of trachea inhalation injury.

Approach: We employed a customized aOCT system that incorporates an intraluminal pressure probe to assess nCsC in vivo in pigs subjected to steam-induced inhalation injuries. Multiple steam intensity levels of injury were induced, and nCsC was measured from the carina to the larynx at time points up to 6 h using aOCT. Histological analysis was performed post-mortem.

Results: We revealed that airway wall nCsC decreased initially after injury but exhibited recovery at 4 h. This is supported by ANOVA results showing that nCsC was significantly influenced by time ( $p=0.002$ ). Linear regression indicated that nCsC was negatively correlated with anatomical position ( $p=0.047$ ), whereas histological injury grade was positively correlated with position ( $p=0.015$ ). In other words, nCsC decreased and injury grading increased when closer to the site of steam introduction.

Conclusions: Airway wall nCsC is a promising quantitative metric for assessing inhalation injury. Future translation of this aOCT-based technology to humans may potentially enhance clinical management of inhalation injuries.