Pleural Effusion - PDF

Pleural effusion Prof.Dr.Ahmed Hussein Jasim F.I.B.M.S (resp)  The pleural lining is a serous membrane covering the lung parenchyma, chest wall, diaphragm, and mediastinum. The pleural membrane covering the surface of the lung i...

Pleural effusion Prof.Dr.Ahmed Hussein Jasim F.I.B.M.S (resp)  The pleural lining is a serous membrane covering the lung parenchyma, chest wall, diaphragm, and mediastinum. The pleural membrane covering the surface of the lung is known as the visceral pleura, the parietal pleura covers the remaining structures. In between the visceral and parietal pleurae of each lung is the pleural space, a potential space that contains a thin layer of fluid of ∼10 mL in volume. A pleural effusion is >10 mL accumulation of fluid in the pleural space. The parietal pleura secretes ∼2.5 L of fluid daily, which is A hemothorax refers to a pleural effusion that is comprised mainly of blood. reabsorbed by the visceral pleura. Chylothorax is a collection of chyle within the pleural space. The two major classes of transudates, which are caused by systemic influences on pleural fluid formation or resorption, exudates, which are caused by local influences on pleural fluid formation and resorption. pleural effusions are Common causes of transudative effusions are left ventricular heart failure, cirrhosis, and nephrotic syndrome. Common causes of exudative effusions are bacterial pneumonia, malignancy, viral infection, and pulmonary embolism. Commonest causes of pleural effusion in the UK and US (in order): cardiac failure, pneumonia, malignancy, PE. Clinical features May be asymptomatic or associated with breathlessness, dry cough, pleuritic chest pain (suggesting pleural inflammation), chest ‘heaviness’, and sometimes pain referred to the shoulder or abdomen signs on examination include reduced chest expansion, reduced tactile vocal fremitus, a stony dull percussion note, quiet breath sounds, and sometimes a patch of bronchial breathing above the fluid level. a friction rub may be heard with pleural inflammation. Imaging CXR Sequential blunting of posterior, lateral, and then anterior costophrenic angles are seen on radiographs as effusions increase in size PA CXr will usually detect effusion volumes of 200mL or more; lateral CXr is more sensitive and may detect as little as 50mL pleural fluid Classical CXr appearance is of basal opacity obscuring hemidiaphragm, with concave upper border. 2.Ultrasound of the chest has a much higher sensitivity than CXr at detecting and localizing pleural fluid and is useful for distinguishing pleural fluid from pleural masses or thickening. chest ultrasound can guide thoracentesis procedures 3.Computed tomography of the pleural contrast is useful in distinguishing benign and malignant pleural disease: nodular, mediastinal, or circumferential pleural thickening and parietal pleural thickening >1cm are all highly specific for malignant disease. scans are best performed prior to complete drainage of fluid 4.Magnetic resonance imaging (MRI ) is unclear; it may have increasing role in distinguishing benign from malignant pleural disease. 5.Thoracentesis (= ‘pleural tap’ or pleural fluid aspiration) may be diagnostic and/or therapeutic, depending on the volume of fluid removed. Following diagnostic tap: note pleural fluid appearance Send sample to biochemistry for measurement of glucose, protein, and lactate dehydrogenase (LDH) Send a fresh 20mL sample in sterile pot to cytology for examination for malignant cells (yield 60% in malignancy) and differential cell count Send samples in sterile pot to microbiology for Gram stain and microscopy, culture. For suspected pleural infection, also send pleural fluid in blood culture bottles. Low threshold for AFB stain and tB culture Process non-purulent, heparinized samples in ABG analyser for pH Consider measurement of cholesterol, triglycerides, chylomicrons, haematocrit, adenosine deaminase, and amylase, depending on the clinical circumstances. Is the pleural effusion a transudate or an exudate ? Helpful in narrowing the differential diagnosis. In patients with a normal serum protein, pleural fluid protein 30g/L = exudate. In borderline cases (protein 25–35g/L) or in patients with abnormal serum protein, Apply Light’s criteria—effusion is exudative if it meets one of following criteria. Pleural fluid protein/serum protein ratio >0.5 Pleural fluid LDH/serum LDH ratio >0.6 Pleural fluid LDH > two-thirds the upper limit of normal serum LDH 6.Pleural tissue biopsy for histology and tB culture using image-guided or thoracoscopic biopsies.  Parapneumonic effusion and empyema Definition and pathophysiology pleural effusions occur in up to 57% of patients with pneumonia. an initial sterile exudate (simple parapneumonic effusion) may, in some cases, progress to a complicated parapneumonic effusion and eventually empyema pleural infection may also occur in the absence of a preceding pneumonic illness (‘primary empyema’). Clinical features Consider the diagnosis particularly in cases of ‘slow-to-respond’ pneumonia (e.g. failure of CRP to fall ≥50% in first 3 days ), pleural effusion with fever, or high- risk groups with non-specific symptoms such as weight loss , anaerobic empyema may present less acutely, often with weight loss and without fever. Risk factors for developing empyema include diabetes, alcohol abuse, gastro- oesophageal reflux, and IV drug abuse. anaerobic infection is associated particularly with aspiration or poor dental hygiene. clinical variables associated with development of pleural infection in those with pneumonia: albumin 100mg/L, platelets >400 × 10 9/l, sodium