5. Pleural Diseases.pdf

Approach to the patient with shortness of breath and chest pain (pleural effusion and pneumothorax) Muhammad S. Mahmood 3rd Oct 2020 Muhammad S. Mahmood HMU-Internal Medicine Chest pain and Shortness of breath Are common symptom...

Approach to the patient with shortness of breath and chest pain (pleural effusion and pneumothorax) Muhammad S. Mahmood 3rd Oct 2020 Muhammad S. Mahmood HMU-Internal Medicine Chest pain and Shortness of breath Are common symptoms The differential diagnosis is wide Detailed history and thorough physical examination are very important to decide further diagnostic pathways  Investigations for chest pain and Shortness of breath ECG CXR PA view Troponins D dimer ABG analysis  The pleural space The pleural space is a potential space that contains 2 to 10 mL of pleural fluid between visceral and parietal pleural layers that essentially represents interstitial fluid from the parietal pleura Note: this clear fluid lubricates the space between the pleura, allowing the pleura to glide smoothly during inhalation and exhalation Note: the pleural space is lined by two layers – the parietal and visceral pleura The pleura is a thin, serous layer that covers the lungs (visceral pleura) and is reflected onto the chest wall and pericardium (parietal pleura). The visceral pleura is supplied by the pulmonary arterial system and drains into the pulmonary venous system, whereas the parietal pleura is supplied by the systemic arterial system and drains into the systemic venous system  Notes (extra) Most pleural fluid is produced as an ultrafiltrate by the parietal pleura and the production of pleural fluid changes based on the hydrostatic, colloid, and tissue pressures within the pleural space and on the permeability of the pleural membrane. The high capillary pressure associated with the systemic capillaries supplying the parietal pleura as compared with the intrapleural negative pressure produces a pressure gradient favoring filtration into the pleural space. In contrast, low- pressure pulmonary circulation supplies the visceral pleura, producing a much less significant pressure gradient. Pleural fluid is subsequently reabsorbed by the lymphatic stomata of the parietal pleura that open directly into the pleural space, which can increase the drainage flow rate by up to 20 times in response to increased production of pleural fluid. Under normal physiologic conditions, pleural fluid production is well balanced with the rate of absorption so as to maintain a low volume of fluid within this space.  Note: Mechanism of pleural effusion To generate a pleural effusion, there must be an increase in entry rate and/or a reduction in exit rate. To generate a clinically relevant effusion, it is likely that both mechanisms contribute to effusion formation for the following reasons: – In the healthy pleura, the absorbing pleural lymphatics have a large reserve capacity to deal with excess pleural liquid. An isolated increase in entry rate, unless large and sustained, is unlikely to cause a clinically significant effusion. – An isolated decrease in exit rate is also unlikely to cause a large effusion because the normal entry rate is low. Even if the exit of liquid ceased entirely, accumulation of liquid would take many days to become evident.  Pleurisy and pleural effusion Pleurisy is a sharp or ‘catching’ chest pain aggravated by deep breathing or coughing Pleural effusion is accumulation of excess fluid in the pleural space Note: Hemothorax: blood when drained Empyema: Pus Milky  chylothorax (collection of lymphatic fluid) Hydrothorax: collection of serous fluid The nature of the fluid is determined after aspiration (Dr. Muhammad)  The commonest cause of PF is? 1. Heart Failure (note: most common) 2. Pneumonia 3. Pulmonary embolism 4. Tuberculosis 5. CA lung  Pleural Effusion Could be transudate (low protein, low LDH) or exudate (high protein, high LDH) Note: the phrase “‫ ”ئاو لە سنگمە‬may be used by patient to refer to pulmonary edema or pleural effusion Note: It is important to remember that a pleural effusion is not a diagnosis in and of itself but a sign of another process. Light’s Criteria for Exudative PF (pleural fluid) Any of following Note: PF and blood sample needed, – PF protein/serum protein >0.5 as protein and LDH need to be – PF LDH/serum LDH >0.6 measured in both PF and blood – PF LDH >2/3 upper normal serum limit Note: Presence of just one of Light’s criteria is enough to make an effusion exudate. If all three are absent, it’s a transudate.  Common causes Transudative PF Exudative PF Malignancy 1. Congestive heart Mesothelioma failure Bacterial infections 2. Liver Cirrhosis Tuberculosis (note: 3. Nephrotic syndrome especially when it reaches the pleura? Dr. Muhammad) Pulmonary embolism ……etc. Pancreatitis Rheumatoid pleurisy Note: usually due to …….etc. systemic disease  Notes: Causes can be systemic (e.g., HF, hypoproteinemia due to any cause like liver failure or nephrotic syndrome, etc.) or local (e.g., TB, pneumonia, etc.) (Extra) Potential mechanisms for the exudative effusion in TB are direct extension of TB infection into the pleural space and rupture of a subpleural caseous focus into the pleural space, resulting in an immunologic hypersensitivity reaction and subsequent accumulation of fluid Other causes not in the previous slide: – Subphrenic abscess, hydronephrosis (can result In urinothorax) (extra) Urinothorax, a rare cause of pleural effusion (PE), consists of the presence of urine in the pleural cavity. It is generally associated with obstructive urinary disease or urinary tract lesion (e.g., hydronephrosis, BPH, bladder cancer, obstructive lithiasis, etc.) causing accumulation of urine in the retroperitoneal space, which is filtered to the pleural cavity – Pneumonia (called parapneumonic effusion, few cc of effusion??)  A clinical scenario An elderly patient with a history of chronic obstructive pulmonary disease is admitted following an infective exacerbation. The CXR PA view on admission is shown. Which one of the following is the most useful next line investigation? A – Bronchoscopy B - Pleural biopsy C - Computed tomography D - Ultrasound E - Lateral chest x-ray  Answer: D. Ultrasound Ultrasound is recommended as it increases the likelihood of successful pleural aspiration and is sensitive for detecting pleural fluid septations.  Note: clinical signs Physical findings in pleural effusion are variable and depend on the volume of the effusion. Asymmetric chest expansion Increased dullness over the base of the lungs Decreased tactile fremitus Diminished or absent vocal resonance, diminished or absent breath sounds Crackles (above effusion) Can cause a contralateral mediastinal shift if huge  Diagnosis of PF CXR PA view US (also guides thoracentesis) Thoracentesis (pleurocentesis) (Protein, LDH); If exudative, also for PH, glucose, WBCs and differential count, microbiological studies and cytology. – Note: Diagnostic (?? Dr. Muhammad) – Note: the needle should be inserted just above the upper border of the lower rib in the intercostal space to avoid the neurovascular bundle, which is located along the lower edge of each rib. The puncture should be guided by ultrasound or be attempted one intercostal space down from where dullness on percussion starts. – Note: with diagnostic thoracocentesis, 50 mL is drawn. CT chest or CTPA Thoracoscopy and pleural biopsy – Note: Pleural biopsies are helpful for diagnosis, and are usually obtained with pleuroscopy, where an endoscope (pleuroscope) is inserted into the pleural space to examine the pleura, drain fluid, and obtain a biopsy of any pathology seen. – Note: For TB, needle biopsy of the pleura is often required for diagnosis and is recommended over pleural fluid analysis; it reveals granulomas and/or yields a positive culture in up to 80% of cases. Cultures of pleural fluid are positive in only 20-40% of patients. – Note: An effusion should never be drained to dryness before establishing a diagnosis, as biopsy may be precluded until further fluid accumulates.  Notes In some conditions (e.g. left ventricular failure), it is not necessary to sample fluid unless atypical features are present; appropriate treatment should be administered and the effusion re-evaluated. If a patient with pneumonia has a small effusion and is recovering, then aspiration may be not needed unless it’s still present on follow up (Dr. Muhammad) In most other circumstances, however, diagnostic sampling is required. Radiological investigations detect a pleural effusion but not its cause (?? Dr. Muhammad) US and CT of PF  Before and after Aspiration Note: The classical appearance of pleural fluid on the erect PA chest film is of a curved shadow at the lung base (meniscus sign; the upper margin of the opacity is concave and extends higher laterally than medially), blunting the costophrenic angle and ascending towards the axilla Note: A large pleural effusion can cause complete opacification (white-out) of the hemithorax, and this has to be differentiated from a collapsed lung. In a collapsed lung, the mediastinum shifts to the affected side, while with a pleural effusion, it shifts to the contralateral side, away from the opacified side. Note: US vs CXR Ultrasound is more accurate than plain chest X-ray for determining the presence of fluid. US can detect as little as 5 mL of effusion On the CXR, it takes 500 mL of fluid for a pleural effusion to be detected Color of pleural fluid  Gross appearance Straw-colored (note: in CHF) Blood-stained (note: pulmonary infract, malignancy) Purulent Chylous (milky-white) (note: can occur due to obstruction of thoracic duct) Note: Amber-colored in TB  Note: Investigations for pleural fluid sample 1. Biochemical – Protein Can differentiate transudate (low – Lactate dehydrogenase protein, low LDH) and exudate – Glucose (high protein, high LDH) – pH (lower pH can indicate infection) 2. Gram stain, culture and sensitivity, acid-fast stain 3. Cytological examination, e.g., for malignancies and differential count 4. PCR for investigating microorganisms 5. Amylase (high levels indicate esophageal perforation) Note: Pleural fluid cholesterol can also be used to differentiate transudate and exudate  Management of pleural effusion Treat underlying condition (note: for example, diuretics for heart failure) Therapeutic Aspiration – Note: Therapeutic aspiration may be required to palliate breathlessness but removing more than 1.5 L at a time is associated with a small risk of re-expansion pulmonary oedema. – Note: the effusion may be aspirated to dryness and then a CXR is taken to examine the lungs (?? Dr. Muhammad) Pleurodesis (obliteration of the pleural space) (note: patients can still survive without their pleural space [Dr. Muhammad]) – Note: patients with a recurrent pleural effusion secondary to an incurable cause, e.g., malignancy or cirrhosis, should get pleurodesis. – Note: pleurodesis should only be done after the cause has been determined (?? Dr. Muhammad) VATS (Video-assisted Thoracoscopic surgery) – Note: can be used for surgical intervention, e.g., pleurodesis. – Note: Performed by cardiothoracic surgeon. – Note: Thoracotomy (open surgery) may be required, particularly for cases of empyema. Note: you may need to follow up patients in whom no cause is diagnosed (Dr. Muhammad)  Note: Techniques for pleurodesis Can be done chemically/medically or surgically Pleurodesis is commonly accomplished by draining the pleural fluid or intrapleural air followed by either a mechanical procedure or instilling a chemical irritant into the pleural space, which causes intense inflammation and fibrosis subsequently leading to adhesions between the two pleural membrane Chemical pleurodesis: – Refers to the obliteration of the pleural space by the induction of pleural inflammation and fibrosis using a sclerosant – Administered via a chest tube – Agents include talc, tetracyclines (minocycline, doxycycline), bleomycin, Povidone- iodine, etc. Surgical: – Mechanical pleurodesis is mechanical abrasion (also termed dry abrasion) of the parietal pleura during thoracoscopy or thoracotomy or placement of a tunneled pleural catheter, which drains pleural fluid and may induce pleurodesis without instillation of a sclerosing agent. – Pleurectomy  Pneumothorax Is presence of air in the pleural space. Note: pleural effusion is common, but pneumothorax is rare, and is more of a surgical issue rather than a medical issue, so these patients end up in surgical wards.  Classification of Pneumothorax Spontaneous (i.e., on its own, not traumatic) – Primary: occurs in patients with no history of lung disease. Smoking, tall stature and the presence of apical subpleural blebs are risk factors. Air escapes from the lung into the pleural space through rupture of a small pleural bleb, or the pulmonary end of a pleural adhesion Note: peak in young adults Note: apical bullae are more common in smokers (?? Dr. Muhammad) (extra: the mechanism for smoking is unclear; a smoking-induced influx of inflammatory cells may both break down elastic lung fibers, causing bulla formation, and cause small airway obstruction, increasing alveolar pressure and the likelihood of interstitial air leak) – Secondary: Secondary pneumothorax affects patients with pre- existing/underlying lung disease and is associated with higher mortality rates. Most commonly with chronic obstructive pulmonary disease and tuberculosis; also seen in asthma, lung abscess, pulmonary infarcts, lung cancer and all forms of fibrotic and cystic lung disease Traumatic (note: Surgery’s problem): Iatrogenic (e.g. following thoracic surgery or biopsy) or chest wall injury  Note: types of pneumothorax Closed: Where the communication between the airway and the pleural space seals off as the lung deflates and does not re-open, the pneumothorax is referred to as ‘closed’. The mean pleural pressure remains negative, spontaneous reabsorption of air and re-expansion of the lung occur over a few days or weeks, and infection is uncommon. (can resolve spontaneously) Open: the communication fails to seal and air continues to pass freely between the bronchial tree and pleural space. An example is a bronchopleural fistula, which can facilitate the transmission of infection from the airways into the pleural space, leading to empyema. An open pneumothorax is commonly seen following rupture of an emphysematous bulla, tuberculous cavity or lung abscess into the pleural space. (note: does not resolve spontaneously and symptoms may persist [?? Dr. Muhammad]) Tension: Occasionally, the communication between the airway and the pleural space acts as a one- way valve, allowing air to enter the pleural space during inspiration but not to escape on expiration. This is a tension pneumothorax. Large amounts of trapped air accumulate progressively in the pleural space and the intrapleural pressure rises to well above atmospheric levels. This causes mediastinal displacement towards the opposite side, with compression of the opposite normal lung and impairment of systemic venous return, causing cardiovascular compromise. This condition is an emergency and the patient’s condition can deteriorate rapidly, leading to shock and death. A chest tube is required; immediate release of the positive pressure by insertion of a blunt cannula into the pleural space may be beneficial, allowing time to prepare for chest drain insertion.  Clinical features The most common symptoms are sudden-onset unilateral pleuritic chest pain (pleurisy) or breathlessness. – Note: the chest pain is peripheral and is exacerbated by movement of the chest, breathing, and coughing In tension pneumothorax, there is rapidly progressive breathlessness associated with a marked tachycardia, hypotension, cyanosis and tracheal displacement away from the side of the silent hemi-thorax Note: bilateral pneumothorax may also occur (extra: Simultaneous bilateral spontaneous pneumothorax is a rare condition occurring in up to 1.9% of cases of spontaneous pneumothorax) Physical findings of pneumothorax? Physical findings  A clinical scenario A 24-year-old male with no past medical history presents to the Emergency Department with pleuritic chest pain. There is no history of a productive cough and he is not short of breath. Chest x-ray shows a right-sided pneumothorax with a 1 cm rim of air and no mediastinal shift. What is the most appropriate management? A - Immediate 14G cannula into 2nd intercostal space, mid-clavicular line B - Discharge with outpatient chest x-ray C - Aspiration D - Intercostal drain insertion E - Admit for 48 hours observation  Answer: B. Discharge with outpatient chest x-ray It would of course be prudent to give advice about what he should do if his symptoms worsen and also suggest routine follow-up with his GP  Investigations CXR – Note: The chest X-ray shows the sharply defined edge (visceral pleura) of the deflated lung with complete translucency (no lung markings) between this and the chest wall CT chest (in difficult cases)  Management No intervention – Note: Patients with a closed pneumothorax should be advised not to fly, as the trapped gas expands at altitude. After complete resolution, there is no clear evidence to indicate how long patients should avoid flying for, although British Thoracic Society guidelines suggest that waiting 1–2 weeks, with confirmation of full inflation prior to flight, is prudent. O2 therapy Percutaneous needle aspiration of air Chest drain Management of spontaneous pneumothorax. (1) Immediate decompression prior to insertion of the intercostal drain. (2) Aspirate in the second intercostal space anteriorly in the mid-clavicular line using a 16 F cannula; discontinue if resistance is felt, the patient coughs excessively, or more than 2.5 L of air are removed. (3) The post-aspiration chest X-ray is not a reliable indicator of whether a pleural leak remains, and all patients should be told to attend again immediately in the event of deterioration.  Notes on management Primary pneumothorax, young patient, otherwise normal lung  follow up and O2 therapy (Supplemental oxygen may speed resolution, as it accelerates the rate at which nitrogen is reabsorbed by the pleura) Secondary pneumothorax of any degree  chest tube