Vignon et al used ultrasonography to estimate the volume of pleural effusions in critically ill patients. The authors are from the Dupuytren Teaching Hospital in Limoges, France.
Ultrasonography was performed with the person in a supine position (appropriate for a critically ill patient in the ICU).
Features of a pleural effusion:
(1) echo-free space located above the diaphragm limited by both pleural layers (appearing as strong ultrasound interface)
(2) variation in interpleural space during the respiratory cycle, with minimum at end-inspiration
Estimates of pleural effusion volume:
(1) rule to predict if >= 800 mL
(2) formulae for volume during end-expiration at base
(3) other formulae
|
Lung Base at End-Expiratory |
Measurement Indicating Volume >= 800 mL |
|
left |
> 50 mm |
|
right |
> 45 mm |
Performance:
• The left estimate had a sensitivity of 100% and specificity of 67%.
• The right estimate had a sensitivity of 94% and specificity of 76%.
Formulae with highest values for r-squared (left 0.51, right 0.78):
|
Base at End-Expiration |
Formula for Mean Effusion Volume in mL |
|
left base end-expiration |
(16.7 * (max interpleural distance in mm)) + 37 |
|
right base end-expiration |
(31.4 * (max interpleural distance in mm)) - 552 |
Other formulae:
|
Timing |
Site |
Formula for Mean Effusion Volume in mL |
|
end-expiration |
left apex |
(13.5 * (max interpleural distance in mm)) + 297 |
|
end-inspiration |
left apex |
(14.8 * (max interpleural distance in mm)) + 343 |
|
end-inspiration |
left base |
(17.8 * (max interpleural distance in mm)) + 110 |
|
end-expiration |
right apex |
(34.1 * (max interpleural distance in mm)) - 492 |
|
end-inspiration |
right apex |
(33.5 * (max interpleural distance in mm)) - 222 |
|
end-inspiration |
right base |
(31.6 * (max interpleural distance in mm)) - 348 |
from Figures 2 and 3 pages 1759 and 1760
Specialty: Pulmonology
