Radial vs. Femoral Access in IO Procedures

[Jason Iannuccilli]
In general, when we're talking about the technical aspects [of radial access] we always start off with an ultrasound to the forearm while the patient is in recovery. We'll check to make sure that the radial artery is sufficient diameter. I would set the threshold at two millimeters for a minimum diameter just based on the sheath size that we're putting in there, which we'll talk about. But in general there's also data to support that the complication rates are higher when the radial artery diameter is less than two millimeters. So we measure the artery, we do an ultrasound, we kind of follow the vessel up the forearm, make sure that we can't see any sort of radial loop or extreme tortuosity that might make it a difficult procedure. Even if you see a radial loop there are ways to overcome it, but again, it may sway you toward using a femoral access if it's a complete loop, for example.

So once we do the anatomic assessment with ultrasound we usually - you don't have to but we do - assess the completeness of the palmar arch by doing a Barbeau test. So the Barbeau test, I'm sure you guys are familiar with it, but it's basically an Allen's test used with a pulse oximeter that we place on either the thumb or the index finger or the hand. We compress the radial artery and observe the pulse ox's waveform. In general, the degree of depression of that waveform is going to tell you how well the ulnar artery is perfusing that superficial palmar arch. And there are various types of waveforms just based on the change. Type A or a type B is preferred. We have done a couple type Cs and haven't had any major issues with that yet but I would say that it's just a handful of patients that we run that risk with.

So that's sort of the overall assessment. If you've got a Barbeau type A or type B and the radial artery is two millimeters and the ultrasound at least to the forearm looks pretty good I'd say it's a go. And then we prep the patient up, bring him into the room.