Pleural Effusions and Intrapleural Pressures of the Re-expansion Period in Pneumothorax

1) The effusions of the re-expansion period are not ex-vacuo transudates.

2) When the mean negative intrapleural pressure is greater than —15 cm. of water, the formation of fluid is most likely to occur, if fluid is not already present.

3) When the average mean intrapleural pressure during re-expansion is greater than that before re-expansion was started, by 1.1 cm. of water, then the lung is resisting expansion. Records should be sufficient to permit the observation of this pressure difference to be made.

4) The chief cause of pleural effusion in pneumothorax cases during re-expansion of the lung is trauma to thickened pleura incident to pneumothorax treatment.

5) Gradual re-expansion is usually to be preferred to abrupt cessation of refills. Exception may be made in cases in which the visceral pleura is thin and the lung has been observed to have a strong tendency to re-expand.