Thoracocentesis
Summary of the Procedure:
| Indications | To diagnose and remove air or fluid in the pleural space. |
| Limitations | Small volumes of fluid (at the very least 5 mL/kg is needed) and localized fluid pockets can be difficult to target.
Occlusion of the needle by fat, fibrin will result in false-negative results or decrease fluid yield. |
| Complications | Trauma to lungs, vessels (iatrogenic pneumothorax, hemothorax). |
| Contraindications | Severe coagulopathy; skin infection an entry site (choose another site). |
| Supplies/instruments | 18-22 gauge needle, 19–21 ga butterfly, 18-22 ga over-the-needle IV catheter (extra-side holes may be cut with a scalpel blade along the catheter tip but this will increase tissue drag).
Syringe +/- extension set for easier maneuverability around patient. Three-way stopcock – helpful when removing large volumes of fluid/air so that syringe doesn’t have to be detached from catheter when voiding sample/air and re-aspirating. |
| Position | Sternal or lateral recumbency. |
| Restraint | Typically performed under sedation, can also be performed under anesthesia.
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Landmarks:
- 7th to 9th intercostal space
- If aspirating fluid, at the level of the costochrondral junction; in case of pneumothorax, approximately in the dorsal third of the space between the top of the rib and the costochondral junction.
Details of the Procedure:
- Position animal in sternal or lateral recumbency. Sedation of animal facilitates positioning.
- Clip and aseptically prepare over the 7th to 9th intercostal space, at your landmark.
- Optionally infiltrate entry site with lidocaine prior to needle entry. Lidocaine is not usually used if the purpose of the procedure is diagnostic (i.e. to see if fluid is present), because the lidocaine injection may be as or more painful than the thoracocentesis. Surface anesthesia with EMLA cream should be used if local anesthesia is desired. If fluid is known to be present, then local anesthesia may help keep the animal more calm during larger volume withdrawal.
- Aspirate fluid or air from thoracic cavity; remove needle and perform cytologic and chemical analysis on fluid.