Effect of pulmonary edema on tracheal diameter.
BACKGROUND
Though it is well known that cardiogenic and noncardiogenic pulmonary edema can cause changes in lung mechanics, actual alterations in tracheal diameter have not been described.


OBJECTIVE
To evaluate the effects of pulmonary edema induced by increased left atrial pressure (cardiogenic) and Perilla ketone (PK; noncardiogenic) on tracheal diameter in chronically instrumented awake sheep.


METHODS
We investigated the effects of two mechanistically distinct types of pulmonary edema on tracheal diameter in chronically instrumented awake sheep. Cardiogenic pulmonary edema (analogous to congestive heart failure in humans) was induced by increasing left atrial pressure ( upward arrowP(LA)) by inflating the balloon on a Foley catheter positioned in the mitral valve annulus to cause partial obstruction to flow across the valve (n = 18). Noncardiogenic pulmonary edema (increased pulmonary microvascular permeability pulmonary edema analogous to the acute respiratory distress syndrome in humans) was produced by the intravenous administration of PK (n = 11). Lateral chest radiographs (CXRs) were scored by a standardized 5-point scoring system for the severity of pulmonary edema, and tracheal diameter was measured at a fixed location in the carina. Three radiologists, blinded to sheep identification number and experimental protocol, evaluated the radiographs independently at different points in time for edema severity and tracheal diameter. The sheep were sacrificed immediately after the final CXR, and wet/dry lung weight ratio (W/D ratio) was determined.


RESULTS
Both upward arrowP(LA) and PK were associated with statistically significant tracheal narrowing ( upward arrowP(LA): 20.3 +/- 0.6 to 15.1 +/- 0.9 mm; PK: 20.2 +/- 0.6 to 14.1 +/- 1.4 mm). Tracheal narrowing correlated with the severity of the pulmonary edema determined radiographically ( upward arrowP(LA): r = -0.69, p < 0.01; PK: r = -0.62, p < 0.01) and by W/D ratio ( upward arrowP(LA): r = -0.64, p < 0.05; PK: r = -0.54, p < 0. 05).


CONCLUSIONS
We conclude that tracheal narrowing occurs in sheep models of both cardiogenic and noncardiogenic pulmonary edema and that the degree of narrowing correlates with the severity of the edema.
Snapper
J R
JR
The Center for Lung Research, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
Trochtenberg
D S
DS
Hwang
Y S
YS
Lefferts
P L
PL
Carroll
F E
FE
Worrell
J A
JA
O'Donnell
D M
DM
D000818:Animals; D003251:Constriction, Pathologic / Q000000981:diagnostic imaging / Q000503:physiopathology; D004195:Disease Models, Animal; D004489:Edema, Cardiac / Q000150:complications* / Q000000981:diagnostic imaging; D016014:Linear Models; D008168:Lung / Q000473:pathology; D039821:Monoterpenes; D009929:Organ Size; D011654:Pulmonary Edema / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology; D011859:Radiography; D012016:Reference Values; D012720:Severity of Illness Index; D012756:Sheep; D013729:Terpenes; D014132:Trachea / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014133:Tracheal Diseases / Q000000981:diagnostic imaging* / Q000209:etiology*
D039821:Monoterpenes; D013729:Terpenes; C015426:perilla ketone