Histological findings of tracheal samples from COVID-19 positive critically ill mechanically ventilated patients

This study examines the histological findings of tracheal tissue samples obtained from COVID-19 positive mechanically ventilated patients, to assess the degree of tracheal inflammation/ulceration present.

Retrospective single-centre observational cohort study. All patients admitted to Adult Intensive Care Unit (AICU) with COVID-19 infection, requiring mechanical ventilation and surgical tracheostomy between 1 April and 1 May 2020, were included (Group 1). Tracheal windows excised at tracheostomy underwent histological analysis. Comparison was made with: tracheal windows from COVID-19 positive AICU ventilated patients admitted between 1 January and 1 March 2021 (Group 2); tracheal windows from COVID-19 negative AICU ventilated patients (Group 3); and, tracheal autopsy samples from COVID-19 positive patients that died without undergoing prolonged mechanical ventilation (Group 4).

Group 1 demonstrated mild/moderate inflammation (tracheitis) in nearly all samples (15/16, 93.8%), with infrequent micro-ulceration (2/16, 12.5%). Group 2 demonstrated similar mild/moderate inflammation in all samples (17/17, 100%), with no ulceration. Histological findings of Groups 1 and 2 COVID-19 positive patients were similar to Group 3 COVID-19 negative patients, which demonstrated mild/moderate inflammation (5/5, 100%), with uncommon superficial erosion (1/5, 20%). Group 4 demonstrated mild chronic inflammation or no significant inflammation, with uncommon micro-ulceration (1/4, 25%).

Severe tracheal inflammation was not demonstrated in mechanically ventilated COVID-19 positive patients at the level of the second/third tracheal rings, at the stage of disease patients underwent tracheostomy. Histological findings were similar between mechanically ventilated COVID-19 positive and negative patients. Tracheal ulceration may be a feature of early or severe COVID-19 disease.