The role of small airways in the pathogenesis of SARS-CoV-2 induced lung disease has not been sufficiently studied. Especially it concerns the acute period of disease.
The aim of our study was to find out whether small airways obstruction occurs in acute period of covid-19 infection and whether obstruction resolves within three months.
We selected 18 oxygen dependent patients treated in the hospital for moderate severity covid-19 pneumonia who arrived for control three months after the discharge. Small airways patency was measured by forced oscillation technique (FOT) using portable instrument Tremoflo C-100, Thorasys, Canada.
Indices characterizing small airways resistance and reactance are present in the table. During the acute period the upper limit of normal (ULN) for resistance and reactance indices was exceeded in 11 of 18 patients, but after 3 months ? only in 4 to 5 of 18.
|
Index |
During hospital stay | 3 months after the discharge | p | ||||
| M & CI | Z-score | n>ULN | M & CI | Z-score | n>ULN | ||
| R5-20 | 1,0 (0,7-1,4) | 2.1 (1,0-3,2 | 11/18 | 0,6 (0,3-0,9) | 0,8 (0.1-1,7) | 4/18 | 0.02 |
| Fres | 22 (19-26) | 2,0 (1,3-2,7) | 9/18 | 17 (14-20) | 1,9 (0,4-1,5) | 5/18 | 0,004 |
| AX | 17,4 (11,1-27,5) | 2,4(1,6-2,9) | 11/18 | 8,0 (4,5-14,4) | 1,1 (0,4-1,7) | 5/18 | 0,006 |
M & CI ? mean and confidence interval; ULN ? upper limit of normal
We conclude that small airways become obstructed during acute period of covid-19 pneumonia. This condition resolves in 3 months in majority of patients, however one third of patients still have signs of small airways disease after 3 months recovery period.