Tracheobronchial injury, including necrotizing tracheobronchitis, may occur as a complication to high frequency jet ventilation. The severity of the injury can be quantitated during microscopic examination of a biopsy using a histopathologic scoring system.
Histopathologic parameters evaluated:
(1) intraepithelial mucus loss
(2) cilia loss
(3) submucosal hemorrhage
(4) surface epithelial changes
(5) PMN leukocyte infiltration
(6) epithelial erosions
(7) necrosis
Parameter
Finding
Points
intraepithelial mucus loss
absent
0
focal
1
diffuse
2
cilia loss
absent
0
focal
1
diffuse
2
submucosal hemorrhage
absent
0
minimal
1
severe
2
surface epithelial changes
absent
0
hyperplasia
1
squamous metaplasia
2
entire loss of epithelium
3
PMN leukocyte infiltration
absent
0
focal, scattered
1
focal, dense
2
diffuse, scattered
3
diffuse, dense
4
epithelial erosions
absent
0
1 area
1
2- 3 areas
2
> 3 areas or extensive
3
total
4
necrosis
absent
0
1 area
1
2- 3 areas
2
> 3 areas or extensive
3
total
4
from Table page 115, Clark (1987)
where:
• PMN = polymorphonuclear
• In the original table, the entry "> 3 areas or extensive" did not have a ">"; I added this to distinguish it from "2-3".
histopathologic score =
= SUM(points for all 7 parameters)
Interpretation:
• minimum score: 0
• maximum score: 21
• The higher the score, the more severe the injury.
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