To maximize flow, sometimes you will need to move the catheter slightly, rotating, tilting, or slowly withdrawing and advancing it. Remove as much pericardial fluid as feasible, but it may not be possible to remove it all. Usually small residual volumes will drain from the pericardial puncture site and be reabsorbed across the pleural membrane.

Once you can no longer pull fluid into the syringe, remove the catheter with the extension set still attached. Occasionally, rubbing of the catheter on the cardiac surface will stimulate arrhythmias, and, if severe, you should immediately remove the catheter. A skin bandage is not necessary, and dogs can often be discharged the day of the procedure. Place samples of the effusion in EDTA and plain tubes for analysis, and record the total fluid volume withdrawn. Antibiotic treatment is unnecessary as long as sterile technique is maintained.

Ultrasound guidance can be helpful if the effusion volume is small, but it is difficult to maintain sterility in the field while manipulating an ultrasound probe. Therefore, we do not recommend using ultrasonography during the pericardiocentesis procedure itself. It can be used, however, to select a site for catheter placement and to assess residual pericardial effusion.

Potential complications

The most common complication of pericardiocentesis is cardiac arrhythmia due to epicardial irritation or cardiac puncture. Withdrawal of the catheter usually stops the arrhythmias. If the heart or vena cava is punctured, it is possible to remove a large amount of blood. Therefore, it is crucial to monitor the presumed effusion for clotting.

There is also a small risk of lung or coronary artery laceration. Although very rare, lung laceration may result in pneumothorax, and coronary laceration may result in an infarct or even sudden death. Fortunately, following good technique makes these consequences rare.

Ideally, all of the pericardial effusion will be removed, but marked clinical benefit is derived from even modest decreases in intrapericardial pressure. Once a catheter has entered the pericardial sac, it is difficult to avoid cardiac puncture if you immediately attempt a second pericardiocentesis (i.e. if the catheter was inadvertently withdrawn from the pericardial sac). Therefore, you should only repeat the procedure if cardiac tamponade is present or persists.

If the pericardial sac has been punctured but the catheter has been withdrawn before the fluid is removed, it is presumed that the effusion may drain to the thorax. Depending on the animal's clinical signs, the fluid is left to be reabsorbed.