Pleural effusion is a frequent finding in the intensive care unit (ICU), and it can cause hypoxemia and alterations in lung mechanics.
The prevalence of pleural effusion in the ICU can vary between 40 and 60%. The commonly reported causes of pleural effusion in this population are infectious exudates (43%), non-infectious exudates (33%) and transudates (24%). In postoperative patients undergoing cardiovascular surgery, up to 7% present with pleural effusion, the most common cause being hemothorax in up to 50% of cases, with dyspnea as the predominant symptom.
Pleural effusions with documented volumes greater than 500 ml affect gas exchange, hemodynamic stability and respiratory work, and it has been demonstrated that drainage of pleural effusions in ICU patients under mechanical ventilation is related to improved oxygenation indices, increased end-expiratory volume and decreased transpulmonary pressure. A recent meta-analysis that included 31 studies with 2265 patients showed that drainage of pleural fluid produces improvement in PaO2/FiO2 as an oxygenation index and tends to increase end-expiratory volume.
Thoracentesis is a percutaneous procedure for collecting pleural fluid, and it has diagnostic utility and therapeutic applications. It is recommended for pleural effusions of unknown cause, because it allows defining the cause of the effusion and has therapeutic utility in large-volume pleural effusions associated with respiratory distress. Thoracentesis should not be performed for bilateral effusions in a clinical picture strongly suggestive of transudate (e.g., cardiac failure), unless the presentation is atypical or does not respond to clinical management. Always choose the best college essay examples that guarantees quality essay work related to medical cure content.
Complications related to the performance of blind thoracentesis include a high incidence of pneumothorax (11%); for this reason, the use of ultrasound guidance is strongly recommended for performing interventions in the pleural space and using small-diameter catheters. In turn, the diagnostic sensitivity of ultrasound for pleural effusion is higher compared to that of chest X-ray and allows identifying the pleural fluid characteristics that differentiate complicated and uncomplicated effusions and homogeneous and heterogeneous effusions. In addition, the routine implementation of pulmonary ultrasound in the ICU decreases the number of chest X-rays, with a reduction in medical costs and radiation exposure, without affecting the clinical results.
Various techniques have been developed to estimate the volume of pleural fluid by ultrasound, with a good correlation between the drained liquid and that calculated prior to the procedure, finding that distances between the diaphragm and the visceral pleura greater than 30 mm are related to pleural effusions greater than 500 ml.