Effect of Ultrasound-Guided Thoracocentesis on Clinical and Physiological Outcomes in Mechanically Ventilated Patients

Background: Pleural effusions are common in critically ill patients, causes are multifactorial. Mechanical ventilation and critical illness lead to disturbance of the normal physiological processes which regulate pleural fluid homeostasis. Ultrasound can detect small volume of pleural effusion up to 20 mL. Aim of the work: We investigated the influence of large pleural effusion drainage on oxygenation, hemodynamics, and respiratory mechanics in mechanically ventilated patients. Methodology: We performed a prospective observational study on 65 mechanically ventilated patients examining the effects of large pleural fluid drainage on oxygenation; PaO2/FiO2 and Respiratory mechanics; peak inspiratory pressures, plateau pressures, dynamic compliance and total PEEP. Hemodynamics and complications also recorded at baseline, 6 h and 24 h after drainage. Results: Among 65 patients, the mean volume of effusion drained was (1868 ± 640) ml at 24 h. Uncomplicated pneumothorax occurred in two patients. When compared baseline; 6 h and 24 h after drainage,PaO2/FiO2 ratio significantly improved (196.69 ± 34.27, 227.02 ± 35.81, 269.78 ± 48.39; p<0.001), with a decrease in peak inspiratory pressure (38.23 ± 5.71, 34.14 ± 4.70, 29.89 ± 4.58 cm H2O, p<0.001) and plateau pressures (21.06 ± 3.47, 18.77 ± 3.17, 15.49 ± 2.91 cm H2O, p<0.001) and a large increase in dynamic compliance (17.48 ± 4.12, 21.79 ± 4.47, 26.77 ± 4.94 ml/cm H2O, p<0.001). Hemodynamics were not changed by drainage apart from respiratory rate which decreased significantly (19.4 ± 5.5, 17.4 ± 5, 16.5 ± 6.8 breaths/min, P=0.019). Conclusions: Ultrasound pleural effusion drainage in mechanically ventilated patients is safe. It appears to ameliorate oxygenation and respiratory mechanics and reducing the respiratory rate without affecting hemodynamics.