ECMO circuits usually have a side port just downstream of the pump that is used for continuous renal replacement therapy (CRRT). The side port allows blood to be easily drawn off from the circuit, and returned after going to the dialysis filter. This is incredibly convenient as most patients that are initiated on ECMO often have concomitant renal failure requiring either full continuous hemodialysis or at least ultrafiltration for volume overload. The flows in the ECMO circuit can reach 5 L/min and the blood through the CRRT circuit is only 100-200 m/min so it represents a very small portion of the total blood flow. While Perfusionists are often reluctant to use the circuit for hemodialysis, the availability of the side ports eliminates the problem of additional patient venous access for the dialysis catheter.
The location of the side port and relationship to the pump can be seen in the photo below. The side port has a Luer-Lok connector and projects orthogonally from the tubing of the ECMO circuit.
Unfortunately, the side ports represent have a significant safety concern in addition to their benefit. Because they stick out 2-3 cm from the tubing at about waist height, they can get caught in clothing (eg. White coats) or be bumped fairly easily which can cause them to crack or break off.
The close-up photo above shows the moment arm that allows significant torque to be applied which can cause damage to the plastic connector. If that happens, a large amount of blood could be lost in a very short period of time putting the patient at significant risk. To stop any bleeding, the tubing should immediately be clamped and the circuit tubing exchanged out.
To provide little additional safety, I taken to placing foam covers over the ports are not in use. It draws attention to them so people are more careful, and hopefully prevents them from getting caught or bumped as easily.