Pericardiocentesis is the process where a needle is passed percutaneously into the pericardial sac to drain accumulated fluid. This can be done in unstable patients with tamponade as a life threatening procedure, as well as on a more semi elective basis for people with chronic recurrent effusions – e.g. malignant or inflammatory.
“Bring it down in a stabbing motion”
The traditional landmark ECG guided methods suffer from the many problems of blind landmark techniques, with high complication rates (20-50%), lower success rates, and prolonged learning curves.
Ultrasound and echocardiographic guidance improves the success rate of this procedure (96-99%), and reduces its complications (1-3%). See this Reference. It is also a lot of fun to do, if that is your sort of thing!
Before performing this procedure, it is important to make sure you are doing the right procedure, on the right patient, with the right equipment. It is important not to delay draining a large, pressurized, or heavily clotted effusion with percutenous methods if the patient needs urgent surgery. As always, consult people who are more experienced.
1) Prescan – The decision about where to go and your approach is a key step in ensuring the success of the procedure. Confirm where the fluid is located, and the area of greatest volume. Try to find the safest site to enter with your needle, that is close to the skin and away from vital structures. The commonest site is via a subcostal approach, but occasionally an apical or even parasternal approach may be used.
2) Equipment – including sterile probe cover, dressings, needle, and drain if required, and monitoring: ECG, blood pressure, staff.
3) Position – patient between you and US screen, and both in a comfortable position. Usually the US probe is held in the left hand, and the needle in the right hand (picture below this is reversed) and can either be in a longitudinal or transverse orientation.
4) PPE – Place on your personal protective equipment in a sterile fashion, and prepare your equipment.
5) Imaging and Puncture – Optimise the image: gain, focus, depth. Advanced the needle keeping the tip in the field by manouvering both left and right hands. This can be difficult if you are not familiar with mediastinal anatomy.
Once you have seen the needle enter the pericardial space, and you have aspirated blood, confirm position with bubble test: a few mls of saline are injected into the space, and when bubbles fill the pericardial sac (rather than ventricle), then blood aspirated can be confirmed from pericardium.
6) Drainage. Often draining only 50mls is all you need to relieve the tamponade physiology – enough time to call for theatres if needed! More will be need to be drained from chronic effusions, which can be large
7) Evaluate for complications – Pneumothorax, hepatic injury, ventricular puncture with massive haemorrhage, arrhythmia, and death.
8) Document your procedures.
Limitations: There are several limitations when using US to guide pericardiocentesis, including subcutaneous emphysema, losing the needle tip from the image, and desterilization of probe.
These limitations can be mitigated by excellent US access technique, and plenty of practise developing your skills in other less critical areas such as venous cannulation.
Aidan, any thoughts on how to best avoid left mammary artery or lung?
And when you think a subcostal approach is best but you have a large liver on the way?
And can you please upload some examples of effusions that are better managened with different approaches?
There are pros and cons for each location – in subcostal, the heart is often deeper, and the liver may be in the way. The apical position may be closer, but you have to be careful about causing a pneumthorax or hitting an intercostal vessel.
The best approach is to visualise all the anatomy at each site before on your prescan, then make an informed decision about the risk and benefits of each approach. You should look at each area, for depth, surrounding structures, and depth of the effusion.
Hope that helps!