Rationale: Lung reexpansion after pleural effusion aspiration is composed of reaeration and reventilation. Previous studies evaluated only the immediate reaeration, and the reventilation was not evaluated using a direct lung ventilation measurement method. Also, indirect evidence indicates that the effusion could cause ventilator asynchrony between the lungs. The electrical impedance tomography can directly and reliably measure lung reaeration, reventilation, and synchrony.
Objectives: To evaluate lung reaeration, reventilation, and ventilator synchrony before and over 1 hour after a pleural aspiration.
Methods: A prospective and observational study using electrical impedance tomography to measure the lung reaeration, reventilation, and ventilatory synchrony between the lungs (through phase angle) before and over 1 hour after the pleural aspiration of 22 patients with unilateral malignant effusions.
Measurements and main results: The ipsilateral (affected by the effusion) (P < 0.001) and contralateral (P = 0.008) lung reaerated immediately without further reaeration over the next hour. However, the reventilation response was heterogeneous, with patients increasing, maintaining, or decreasing ipsilateral lung ventilation after the aspiration. The pleural effusion had caused ventilatory asynchrony (93 ± 71 degrees) that was immediately reversed by the aspiration. In some patients, the asynchrony was so extreme that one lung was inflating while the other was deflating, causing paradoxical ventilation.
Conclusions: After a pleural effusion aspiration, the ipsilateral and contralateral lungs reaerate immediately without further reaeration over the next hour. The reventilation shows a heterogeneous response, with patients increasing, maintaining, or decreasing the ipsilateral lung ventilation. The pleural effusion causes a ventilatory asynchrony between the lungs that is immediately decreased by the aspiration. In some patients, that asynchrony is so intense that it causes paradoxical ventilation.