File Name: difference between exudate and transudate .zip
A more recent article on this topic is available. The serum to pleural fluid protein or albumin gradients may help better categorize the occasional transudate misidentified as an exudate by these criteria.
If the patient has a transudative effusion, therapy should be directed toward the underlying heart failure or cirrhosis.
If the patient has an exudative effusion, attempts should be made to define the etiology. Pneumonia, cancer, tuberculosis, and pulmonary embolism account for most exudative effusions. Many pleural fluid tests are useful in the differential diagnosis of exudative effusions.
Other tests helpful for diagnosis include helical computed tomography and thoracoscopy. Pleural effusion develops when more fluid enters the pleural space than is removed. Potential mechanisms of fluid increased interstitial fluid in the lungs secondary to increased pulmonary capillary pressure i. Although many different diseases may cause pleural effusion, the most common causes in adults are heart failure, malignancy, pneumonia, tuberculosis, and pulmonary embolism, whereas pneumonia is the leading etiology in children.
Thoracentesis should be performed in all patients with more than a minimal pleural effusion unless clinically evident heart failure is present.
An effusion is exudative if it meets any of the following three criteria: 1 the ratio of pleural fluid protein to serum protein is greater than 0. The serum-effusion protein or albumin gradients can be used to diagnose the presence of a transudate after diuresis.
In a lymphocyte-predominant exudate, a pleural fluid adenosine deaminase greater than 40 U per L nkat per L indicates that the most likely diagnosis is tuberculosis.
If malignancy is a concern and cytologic examination is nondiagnostic, thoracoscopy should be considered. The history and physical examination are critical in guiding the evaluation of pleural effusion Table 1.
Signs and symptoms of an effusion vary depending on the underlying disease, but dyspnea, cough, and pleuritic chest pain are common. Chest examination of a patient with pleural effusion is notable for dullness to percussion, decreased or absent tactile fremitus, decreased breath sounds, and no voice transmission.
Dyspnea on exertion, orthopnea, peripheral edema, elevated jugular venous pressure. Posteroanterior and lateral chest radiographs usually confirm the presence of a pleural effusion, but if doubt exists, ultrasound or computed tomography CT scans are definitive for detecting small effusions and for differentiating pleural fluid from pleural thickening.
On a posteroanterior radiograph, free pleural fluid may blunt the costophrenic angle; form a meniscus laterally; or hide in a subpulmonic location, simulating an elevated hemidiaphragm. Posteroanterior radiograph demonstrating blunting of the left costophrenic angle. Left lateral decubitus of the same patient demonstrating a large amount of free pleural fluid. Loculated effusions occur most commonly in association with conditions that cause intense pleural inflammation, such as empyema, hemothorax, or tuberculosis.
Occasionally, a focal intrafissural fluid collection may look like a lung mass. This situation most commonly is seen in patients with heart failure. The disappearance of the apparent mass when the heart failure is treated definitively establishes the diagnosis of pseudotumor i. Heart failure is by far the most common cause of bilateral pleural effusion, but if cardiomegaly is not present, other causes such as malignancy should be investigated. Large effusions may opacify the entire hemithorax and displace mediastinal structures toward the opposite side.
More than one half of these massive pleural effusions are caused by malignancy; other causes are complicated parapneumonic effusion, empyema, and tuberculosis. Except for patients with obvious heart failure, thoracentesis should be performed in all patients with more than a minimal pleural effusion i.
Thoracentesis is urgent when it is suspected that blood i. If difficulty in obtaining pleural fluid is encountered because the effusion is small or loculated, ultrasound-guided thoracentesis minimizes the risk for iatrogenic pneumothorax. This is the case when malignant cells, microorganisms, or chyle are found, or when a transudative effusion is found in the setting of heart failure or cirrhosis. Observing the gross appearance of the pleural fluid may suggest a particular cause.
For example, turbidity of the pleural fluid can be caused either by cells and debris i. A uniformly blood-stained fluid i. Although common, chest radiography is not necessary after thoracentesis unless air is obtained during the procedure; the patient develops symptoms such as dyspnea, cough, or chest pain; or tactile fremitus is lost over the upper part of the aspirated hemithorax.
Pleural effusions are either transudates or exudates based on the biochemical characteristics of the fluid, which usually reflect the physiologic mechanism of its formation. Transudates result from imbalances in hydrostatic and oncotic forces and are caused by a limited number of recognized clinical conditions such as heart failure and cirrhosis. Less common causes include nephrotic syndrome, atelectasis, peritoneal dialysis, constrictive pericarditis, superior vena caval obstruction, and urinothorax.
Transudative effusions usually respond to treatment of the underlying condition e. In contrast, exudates occur when the local factors influencing the accumulation of pleural fluid are altered. Exudates present more of a diagnostic dilemma. Pneumonia, malignancy, and thromboembolism account for most exudative effusions in the United States Table 2.
Reprinted with permission from Light RW. Clinical practice. Pleural effusion. N Engl J Med ; These criteria classify an effusion as exudate if one or more of the following are present: 1 the ratio of pleural fluid protein to serum protein is greater than 0.
This lower sensitivity may be caused by the fact that a single test is employed as opposed to the three-test combination of the standard criteria described above. Another approach to the classification of pleural effusions is to apply continuous or multilevel likelihood ratios Table 3 A meta-analysis derivation of continuous likelihood ratios for diagnosing pleural fluid exudates.
In patients with exudative effusion, the following pleural fluid tests should be performed on fluid obtained during the initial thoracentesis: cell counts and differential, glucose, adenosine deaminase ADA , and cytologic analysis. Pleural fluid for total white blood cell WBC count and differential cell count should be sent in an anticoagulated tube. If the fluid is sent in a plastic or glass tube without anticoagulation, the fluid may clot, resulting in an inaccurate count. Thus, the finding of neutrophilrich fluid heightens suspicion for parapneumonic pleural effusion an acute process , whereas a lymphocyte-predominant fluid profile suggests cancer or tuberculosis a chronic process.
In the United States, ADA is not routinely requested because of the low prevalence of tuberculous pleurisy. In general, pleural fluids with a low glucose level also have low pH and high LDH levels.
Most patients who meet the criteria for an exudative effusion with LDH but not with protein levels have either parapneumonic effusions or malignancy.
In purulent fluids, leukocyte count is commonly much lower than expected because dead cells or other debris account for much of the turbidity. The presence of air or blood in the pleural space is a common cause.
No diagnosis is ever obtained in as many as one third of patients with eosinophilic pleural effusion. In about 7 percent of acute tuberculous pleurisy and 20 percent of malignant pleural effusions, a neutrophilic fluid predominance can be seen. Information from references 3 , 5 , and Pleural fluid for pH testing should be collected anaerobically in a heparinized syringe and measured in a blood-gas machine.
A low pleural fluid pH value has prognostic and therapeutic implications for patients with parapneumonic and malignant pleural effusions.
A pH value less than 7. Obtain when esophageal rupture or pancreatic disease is suspected. The amylase in malignancy and esophageal rupture is of the salivary type. Measure if chylothorax or pseudochylothorax is suspected. This parameter taken alone misclassifies 10 percent of exudates and 20 percent of transudates. Obtain in all parapneumonic pleural effusions because a positive Gram stain or culture should lead to prompt chest tube drainage. Obtain when pleural fluid is bloody.
Hemothorax most often originates from blunt or penetrating chest trauma. Consider when ADA is unavailable or nondiagnostic and tuberculosis is suspected.
Heart failure If available, consider testing when heart failure is suspected and exudate criteria are met. Obtain in all nonpurulent effusions if infection is suspected. A low pleural fluid pH indicates the need for tube drainage only for parapneumonic pleural effusions. Infection 20 , Consider when infection is suspected.
Sensitivity of polymerase chain reaction to detect Mycobacterium tuberculosis in pleural fluid varies from 40 to 80 percent and is lower in patients with negative mycobacterial cultures. Obtain when pleural fluid is cloudy or milky. Chylothorax is caused by lymphoma or trauma. Not all chylous pleural effusions appear milky white or whitish. Consider when malignancy is suspected and thoracoscopy is being considered.
Information from references 5 and 13 through ADA is an enzyme that plays an important role in lymphoid cell differentiation. A pleural fluid ADA level greater than 40 U per L nkat per L has a sensitivity of 90 to percent and a specificity of 85 to 95 percent for the diagnosis of tuberculous pleurisy.
Cultures for both aerobic and anaerobic bacteria will identify the responsible microorganism in about 40 percent of parapneumonic effusions 70 percent if fluid is grossly purulent. In addition, both pleural fluid and sputum should be cultured for mycobacteria when tuberculous pleuritis is suspected. The yield of sputum cultures in tuberculous pleural effusion varies from 10 to 60 percent, largely dependent on the extent of associated pulmonary involvement. About one third of patients with tuberculous pleuritis have a negative tuberculin skin test.
Cytology is positive in approximately 60 percent of malignant pleural effusions. The diagnostic yield may be somewhat improved by additional pleural taps. Submission of 10 mL of pleural fluid appears adequate for cytologic processing. A second thoracentesis should be considered in the following situations: 1 suspected malignant effusion and the initial pleural fluid cytologic examination is negative; 2 a parapneumonic effusion with borderline biochemical characteristics of the pleural fluid for indicating chest tube drainage; and 3 suspected acute tuberculous pleurisy with initial nondiagnostic pleural ADA levels.
Helical CT has become the first-line modality for imaging of pulmonary circulation in a patient suspected of having pulmonary embolism, supplanting ventilation-perfusion scintigraphy.
The first step in the diagnosis of pleural effusions is the distinction between exudates and transudates. The aim of this study was to evaluate the usefulness of various parameters for the differentiation of pleural exudates and transudates. We recorded clinical characteristics, final diagnoses, and measured pleural fluid and serum levels of albumin, protein, LDH, cholesterol, and bilirubin of consecutive patients with pleural effusion. This is a preview of subscription content, access via your institution. Light R.
Seventy-one (23%) pleural effusions were transudates and were exudates. As a single criterion, the pleural fluid to serum albumin ratio > was the most.
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Hamal, K. Yogi, N. Bam, S. Das, R. To study the diagnostic value of pleural fluid cholesterol in differentiating transudative and exudative pleural effusion. Cross sectional descriptive study.
Correspondence Address : Dr. Background: Differentiating into transudate or exudate is the first step in the evaluation of effusions. Light's criteria is the standard but a significant number of transudates may not be differentiated based on these criteria. Hence, this study was done to know the diagnostic value of pleural fluid pf CP and pf to serum ceruloplasmin ratio CPr to differentiate the pleural effusion PE into exudate and transudate as compared to Light's criteria. Design: Cross-sectional descriptive study. Patients with PE were divided into exudate and transudate by definitive diagnosis.
A more recent article on this topic is available. The serum to pleural fluid protein or albumin gradients may help better categorize the occasional transudate misidentified as an exudate by these criteria. If the patient has a transudative effusion, therapy should be directed toward the underlying heart failure or cirrhosis. If the patient has an exudative effusion, attempts should be made to define the etiology. Pneumonia, cancer, tuberculosis, and pulmonary embolism account for most exudative effusions. Many pleural fluid tests are useful in the differential diagnosis of exudative effusions. Other tests helpful for diagnosis include helical computed tomography and thoracoscopy.
Archivos de Bronconeumologia is a scientific journal that preferentially publishes prospective original research articles whose content is based upon results dealing with several aspects of respiratory diseases such as epidemiology, pathophysiology, clinics, surgery, and basic investigation. Other types of articles such as reviews, editorials, a few special articles of interest to the society and the editorial board, scientific letters, letters to the Editor, and clinical images are also published in the Journal. It is a monthly Journal that publishes a total of 12 issues and a few supplements, which contain articles belonging to the different sections. The Journal is published monthly both in Spanish and English.
Там тоже были группы из четырех знаков. - Потрясающе, - страдальчески сказал директор. - У вас, часом, нет такой же под рукой. - Не в этом дело! - воскликнула Сьюзан, внезапно оживившись.
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