| Thoracentesis | |
|---|---|
 Chest X-ray showing a left-sidedpleural effusion (right side of image). This can be treated with thoracentesis. | |
| ICD-9-CM | 34.91 |
| Othercodes | OPCS-4.2T12.3 |
| MedlinePlus | 003420 |
Thoracentesis/ˌθɔːrəsɪnˈtiːsɪs/, also known asthoracocentesis (from Greek θώραξ (thōrax,GEN thōrakos) 'chest,thorax' and κέντησις (kentēsis) 'pricking, puncture'),pleural tap,needle thoracostomy, orneedle decompression (often used term), is an invasive medical procedure to removefluid orair from thepleural space for diagnostic or therapeutic purposes. Acannula, or hollow needle, is carefully introduced into the thorax, generally after administration oflocal anesthesia. The procedure was first performed byMorrill Wyman in 1850 and then described byHenry Ingersoll Bowditch in 1852.[1]
The recommended location varies depending upon the source. Some sources recommend themidaxillary line, in the eighth, ninth, or tenthintercostal space.[2] Whenever possible, the procedure should be performed under ultrasound guidance, which has shown to reduce complications.[3][4][5]
This procedure is indicated when unexplained fluid accumulates in the chest cavity outside the lung. In more than 90% of cases, analysis of pleural fluid yields clinically useful information. If a large amount of fluid is present, then this procedure can also be used therapeutically to remove that fluid and improve patient comfort and lung function.
The most common causes of pleuraleffusions arecancer,congestive heart failure,pneumonia, and recentsurgery. In countries wheretuberculosis is common, this is also a common cause of pleural effusions.
When cardiopulmonary status is compromised (i.e. when the fluid or air has its repercussions on the function of heart and lungs), due to air (significantpneumothorax), fluid (pleural fluid) orblood (hemothorax) outside the lung, then this procedure is usually replaced withtube thoracostomy, the placement of a large tube in the pleural space.
An uncooperative patient or acoagulation disorder that cannot be corrected are relative contraindications.[7] Routine measurement of coagulation profiles is generally not indicated, however; when performed by an experienced operator "hemorrhagic complications are infrequent after ultrasound-guided thoracentesis, and attempting to correct an abnormal INR or platelet level before the procedure is unlikely to confer any benefit".[8]
Relative contraindications include cases in which the site of insertion has knownbullous emphysema, use ofpositive end-expiratory pressure (PEEP, seemechanical ventilation) and only one functioninglung (due to diminished reserve). Traditional expert opinion suggests that the aspiration should not exceed 1 L to avoid the possible development of pulmonary edema, but this recommendation is uncertain as the volume removed does not correlate well with this complication.[5]
Major complications arepneumothorax (3–30%),hemopneumothorax,hemorrhage, hypotension (low blood pressure due to a vasovagal response) and reexpansionpulmonary edema.
Minor complications include a dry tap (no fluid return), subcutaneoushematoma orseroma, anxiety,dyspnea and cough (after removing large volume of fluid).
The use ofultrasound for needle guidance can minimize the complication rate.[3][4][5]
While chest X-ray has traditionally been performed to assess for pneumothorax following the procedure, it may no longer be necessary to do so in asymptomatic, non-ventilated persons given the widespread use of ultrasound to guide this procedure.[9]
Several diagnostic tools are available to determine theetiology of pleural fluid.
First the fluid is eithertransudate orexudate.
An exudate is defined as pleural fluid to serum total protein ratio of more than 0.5, pleural fluid to serum LDH ratio > 0.6, and absolute pleural fluid LDH > 200 IU or >2⁄3 of the normal.
An exudate is defined as pleural fluid that filters from the circulatory system into lesions or areas of inflammation. Its composition varies but generally includes water and the dissolved solutes of the main circulatory fluid such as blood. In the case of blood it will contain some or all plasma proteins, white blood cells, platelets and (in the case of local vascular damage) red blood cells.
Exudate
Transudate
A high amylase level (twice the serum level or the absolute value is greater than 160 Somogy units) in the pleural fluid is indicative of either acute or chronicpancreatitis, pancreaticpseudocyst that has dissected or ruptured into the pleural space,cancer or esophageal rupture.
Glucose is considered low if pleural fluid value is less than 50% of normal serum value. Thedifferential diagnosis for this is:
Normal pleural fluid pH is approximately 7.60. A pleural fluid pH below 7.30 with normal arterial blood pH has the same differential diagnosis as low pleural fluid glucose.
Chylothorax (fluid fromlymph vessels leaking into the pleural cavity) may be identified by determiningtriglyceride andcholesterol levels, which are relatively high inlymph. A triglyceride level over 110 mg/dl and the presence of chylomicrons indicate achylous effusion. The appearance is generally milky but can beserous.
The main cause for chylothorax is rupture of thethoracic duct, most frequently as a result of trauma or malignancy (such aslymphoma).
The number ofwhite blood cells can give an indication of infection. The specific subtypes can also give clues as to the type on infection. The amount ofred blood cells are an obvious sign of bleeding.
If the effusion is caused byinfection,microbiological culture may yield the infectious organism responsible for the infection, sometimes before other cultures (e.g. blood cultures and sputum cultures) become positive. AGram stain may give a rough indication of the causative organism. AZiehl–Neelsen stain may identifytuberculosis or other mycobacterial diseases.
Cytology is an important tool in identifying effusions due tomalignancy. The most common causes for pleural fluid arelung cancer,metastasis from elsewhere andpleural mesothelioma. The latter often presents with an effusion. Normal cytology results do not reliably rule out malignancy, but make the diagnosis more unlikely.
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