Rhea et al developed a method for estimating the size of pneumothorax based on the upright expiratory chest radiograph.
(1) Measure the shortest distance between the lung marking and the chest wall at 3 points:
(1a) maximum at the apex
(1b) midpoint of upper lung hemithorax
(1c) midpoint of the lower lung hemithorax
(2) Calculate the average value for these measurements.
(3) Look up the percent pneumothorax from the table below.
(1) The medial aspect of the scapula and large emphysematous bullae should not be mistaken for a pneumothorax.
(2) Measurements from a supine radiograph should not be used since the lung markings may extend to the chest wall (as the trapped air moves anteriorly).
Average Measurement in Centimeters
Size Pneumothorax in Percent
from Wyatt (1999) page 114
When this data is analyzed in JMP, the following linear relationship is obtained:
size of the pneumothorax in percent =
= (8.71935 * (average measurement in cm)) + 5.3839
• The equation gave consistent results, with r = 0.96 and the residual error –2.4 +/- 7.23%.
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Purpose: To estimate the size of a pneumothorax based on examination of the upright expiratory chest radiograph using the method of Rhea et al.
Objective: imaging studies