Pleural Effusion - Geeky Medics PDF

10/17/24, 9:02 AM Pleural Effusion | Geeky Medics Key points Pleural effusion: accumulation of fluid in the pleural space, the area between the visceral and parietal pleura. Classification: Transudative:...

10/17/24, 9:02 AM Pleural Effusion | Geeky Medics Key points Pleural effusion: accumulation of fluid in the pleural space, the area between the visceral and parietal pleura. Classification: Transudative: low protein 35g/L; due to increased pleural/capillary permeability (e.g., infection, malignancy). Causes: Transudative: heart failure, cirrhosis, hypoalbuminemia, nephrotic syndrome. Exudative: infection (parapneumonic, tuberculosis), malignancy, pulmonary infarction, autoimmune diseases. Other: haemothorax, empyema, chylothorax. Symptoms: Breathlessness, cough, pleuritic chest pain. ← stnetnoC History: lung cancer symptoms (haemoptysis, weight loss), heart failure symptoms (orthopnoea, PND, leg swelling), infection symptoms (productive cough, fever), social history (smoking, asbestos exposure). Examination findings: Peripheral: nicotine staining, clubbing, signs of fluid overload. Chest: reduced movement, tracheal deviation, reduced expansion, reduced tactile vocal fremitus. Percussion: ‘stony’ dull sound. Auscultation: reduced/absent breath sounds and vocal resonance. Differential diagnoses: Infection (pneumonia, tuberculosis), malignancy, pulmonary embolism, pneumothorax. Investigations: Bedside: ECG (cardiac cause, right heart strain), urine dip (proteinuria). Laboratory: FBC/CRP/blood cultures (infection), ABG (oxygenation), D-dimer (PE), LFTs/U&Es/albumin/coagulation profile (liver/renal disease), amylase (pancreatitis), TFTs (hypothyroidism). Imaging: chest X-ray (first-line), CT/ultrasound (further characterisation), echocardiogram (heart failure, right heart strain). Diagnosis: Pleural fluid analysis: biochemistry (protein, LDH, glucose), microbiology (gram stain, culture), cytology. Use Light’s criteria if pleural fluid protein is 25-35g/L. https://geekymedics.com/pleural-effusion/ 3/29 10/17/24, 9:02 AM Pleural Effusion | Geeky Medics Management: Medical: treat underlying cause (e.g., diuretics for heart failure, antibiotics for infection). Observation for small, asymptomatic effusions. Therapeutic aspiration or chest drain for symptomatic patients. Surgical: VATS for further investigation/management. Complications: Respiratory compromise, empyema, sepsis, pneumothorax (due to pleural procedures), poorer prognosis in malignancy or pneumonia. Introduction A pleural effusion is the accumulation of fluid in the pleural space. The pleural space is the area between the visceral and parietal pleura.1 Aetiology ← stnetnoC Anatomy The lungs are surrounded by the pleural membrane. This is a serous membrane divided into the visceral pleura (lines the lungs) and parietal pleura (lines the internal thoracic cavity). The potential space between the visceral and parietal pleura contains a small amount of lubricating serous fluid. The serous fluid allows the visceral and parietal pleura to slide over each other during respiration and creates surface tension between the two layers. Pleural effusions occur when fluid accumulates in the pleural space. https://geekymedics.com/pleural-effusion/ 4/29 10/17/24, 9:02 AM Pleural Effusion | Geeky Medics Figure 1. Anatomy of the chest wall and pleural membranes.2 Classification ← stnetnoC Pleural effusions are usually classified as transudative or exudative. Transudates have a low protein level of 35g/L. Fluid accumulates due to increased pleural and capillary permeability.1 Table 1. An overview of the causes of pleural effusions.1 Type Causes Common: ‘the failures’: heart failure, cirrhosis (liver failure) Transudative Less common: hypoalbuminemia, nephrotic syndrome, peritoneal dialysis, hypo Rare: Meigs’ syndrome (benign ovarian tumour, ascites, pleural effusion) Exudative Common: infection (parapneumonic, tuberculosis), malignancy Less common: pulmonary infarction, autoimmune diseases (e.g. rheumatoid arth https://geekymedics.com/pleural-effusion/ 5/29 10/17/24, 9:02 AM Pleural Effusion | Geeky Medics Rare: yellow nail syndrome, drugs (methotrexate, amiodarone, nitrofurantoin, phe Haemothorax: blood in the pleural space Other Empyema: pus in the pleural space Chylothorax: chyle in the pleural space due to disruption of the thoracic duct (du Clinical features History Small and moderate pleural effusions are commonly asymptomatic. As the pleural effusion increases in size, symptoms begin to develop. ← stnetnoC Typical symptoms of a pleural effusion include:1 Breathlessness Cough Pleuritic chest pain Other important areas to cover in the history include: Symptoms suggestive of lung cancer: haemoptysis, weight loss Symptoms suggestive of heart failure: orthopnoea, paroxysmal nocturnal dyspnoea, leg swelling Symptoms suggestive of infection: productive cough, fever Social history: smoking history (lung cancer risk), asbestos exposure (mesothelioma) Clinical examination In the context of a pleural effusion, a thorough respiratory examination is required. On peripheral inspection lookout for nicotine staining of fingers, clubbing (lung cancer), evidence of joint deformity (rheumatoid arthritis) and signs of fluid overload (heart failure). https://geekymedics.com/pleural-effusion/ 6/29 10/17/24, 9:02 AM Pleural Effusion | Geeky Medics On closer inspection of the chest, a larger pleural effusion may cause reduced chest movement on the affected side. Palpation may reveal tracheal deviation away from the affected side and reduced chest expansion on the affected side. There may also be reduced tactile vocal fremitus over the pleural effusion. On percussion, a pleural effusion classically sounds ‘stony’ dull. When auscultating, breath sounds and vocal resonance are reduced or absent over an effusion. Differential diagnoses Breathlessness, cough and pleuritic chest pain are typical presenting features of a pleural effusion but important differentials to consider include: Infection: such as pneumonia or tuberculosis Malignancy without effusion Pulmonary embolism Pneumothorax ← Investigations stnetnoC Chest X-ray is a useful initial investigation when suspecting a pleural effusion, however, it is important to also consider other investigations to ascertain the aetiology of the effusion. Bedside investigations Relevant bedside investigations include: ECG: to look for a cardiac cause of chest pain and breathlessness or signs of right heart strain which may indicate a pulmonary embolism. Urine dip: to assess for proteinuria which may indicate nephrotic syndrome. Laboratory investigations Relevant laboratory investigations include: FBC/CRP/blood cultures: to look for infection Arterial blood gas: if oxygenation if affected https://geekymedics.com/pleural-effusion/ 7/29 10/17/24, 9:02 AM Pleural Effusion | Geeky Medics D-dimer: if a pulmonary embolism is suspected LFTs, U&Es, albumin, coagulation profile: to look for liver and renal disease Amylase: if pancreatitis is suspected TFTs: if hypothyroidism is suspected Imaging A chest X-ray is the first-line imaging investigation of choice. This is useful to assess a pleural effusion and estimate its size. A unilateral effusion is typically exudative whereas bilateral effusions are typically transudative. 50ml of pleural fluid can cause costophrenic blunting, but >200ml fluid is needed to be visible on PA film.1 A chest X-ray is also useful to assess for the underlying aetiology of the pleural effusion. Look for consolidation (infection), malignancy, cardiomegaly (cardiac failure) and pleural plaques (asbestos exposure). Other relevant imaging investigations include: ← CT or ultrasound chest: to further characterise pleural effusion and investigate for an underlying stnetnoC cause. Echocardiogram: to look for signs of heart failure or right heart strain (which may suggest pulmonary embolism). Figure 3. Chest X-ray showing bilateral pleural effusions. 4 Figure 2. Chest X-ray showing a left-sided pleural effusion. 3 Other investigations https://geekymedics.com/pleural-effusion/ 8/29 10/17/24, 9:02 AM Pleural Effusion | Geeky Medics If a unilateral pleural effusion is thought to be exudative, British Thoracic Society guidelines suggest pleural fluid aspiration (diagnostic) which is usually performed under ultrasound guidance.5 Pleural aspirations are not routinely carried out for bilateral effusions with features suggestive of a transudate.5 Medical thoracoscopy can be used to aid diagnosis in some circumstances. It involves visualising and taking a biopsy of the pleura using a thoracoscope under local anaesthetic. Diagnosis Pleural fluid should be sent for biochemistry (protein, LDH and glucose), microbiology (gram stain and culture) and cytology. More specialist tests may be needed depending on the likely cause of the pleural effusion. If pleural fluid protein is 25-35g/L, Light’s criteria are used to distinguish transudative from exudative pleural effusions. ← stnetnoC Light’s criteria summary The fluid is an exudate if one or more of the following criteria are met:6 Pleural fluid protein divided by serum protein is >0.5 Pleural fluid LDH divided by serum LDH is >0.6 Pleural fluid LDH is >⅔ the upper limit of the laboratory normal value for serum LDH The appearance of the pleural fluid should be noted: purulent fluid suggests infection, bloody fluid may suggest malignancy, pulmonary embolism or trauma. Fluid pH can be analysed in a blood gas machine if the fluid is not purulent. A fluid pH < 7.3 can indicate malignancy, pleural infection, rheumatoid arthritis, tuberculosis and oesophageal rupture. In parapneumonic effusions, pH