Pleural effusions on the intensive care unit; Hidden morbidity with therapeutic potential

Abstract

Despite 50-60% of intensive care patients demonstrating evidence of pleural effusions, there has been little emphasis placed on the role of effusions in the aetiology of weaning failure. Critical illness and mechanical ventilation lead to multiple perturbations of the normal physiological processes regulating pleural fluid homeostasis, and consequently, failure of normal pleural function occurs. Effusions can lead to deleterious effects on respiratory mechanics and gas exchange, and when extensive, may lead to haemodynamic compromise. The widespread availability of bedside ultrasound has not only facilitated earlier detection of pleural effusions but also safer fluid sampling and drainage. In the majority of patients, pleural drainage leads to improvements in lung function, with data from spontaneously breathing individuals demonstrating a consistent symptomatic improvement, while a meta-analysis in critically ill patients shows an improvement in oxygenation. The effects on respiratory mechanics are less clear, possibly reflecting heterogeneity of underlying pathology. Limited data on clinical outcome from pleural fluid drainage exist; however, it appears to be a safe procedure with a low risk of major complications. The current level of evidence would support a clinical trial to determine whether the systematic detection and drainage of pleural effusions improve clinical outcomes.

Year in review 2013: Lung cancer, respiratory infections, tuberculosis, cystic fibrosis, pleural diseases, bronchoscopic intervention and imaging

“…71 For those who are mechanically ventilated, especially, many factors may alter normal pleural fluid turnover and lead to pleural fluid accumulation. About half of the critically ill patients show evidence of pleural effusions by ultrasonography.…”

“…About half of the critically ill patients show evidence of pleural effusions by ultrasonography. 71 The range of potential causes is wide, among which hypoalbuminaemia, fluid overload, heart failure, atelectasis, postoperative effusions and pleural infections are thought to account for many cases. Pleural effusions in this group of patients can have significant deleterious effects on respiratory mechanics and gas exchange and, when large in size, may also affect hemodynamics.…”

“…An excellent review described the limited evidence that exists on the aetiology and physiological effects of pleural effusions in patients admitted to ICU. 71 For those who are mechanically ventilated, especially, many factors may alter normal pleural fluid turnover and lead to pleural fluid accumulation. About half of the critically ill patients show evidence of pleural effusions by ultrasonography.…”

“…Therapeutic thoracenteses under ultrasound guidance improve symptoms, lung function and oxygenation in the majority of cases. 71 However, the effects of systematic pleural drainage on the duration of mechanical ventilation await clinical trials.…”

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

“…Pleural effusion is common in the critically ill, occurring in over 60% of patients in some series [1,2]. Causes are multifactorial as pneumonia, heart failure, excessive intravenous fluid administration, hypoalbuminemia, atelectasis and positive ventilation [1].…”