Difficult IV Access
Venous cannulation is made easier by ultrasound in patients whose veins are difficult to see. There are a variety of patient populations that require advanced IV assistance, often, obese patients that are in renal failure. Many of these patients have only a selective area that is available for IV cannulation due to surgical stipulations or previous graft sites. Having an idea where to place a probe will make hunting for a proper vein quicker. The cephalic vein runs on the lateral side of the biceps muscle then traverses the radial side of the forearm. It is a large vessel that’s relatively easy to find. This is a frequent site for PICC line placement. The basilic vein runs down the medial side of the biceps muscle and traverses down to join the cephalic to form the characteristic “Y” of the antecubital area. It also traverses the medial side of the forearm and terminates in the ulnar side of the hand. If these prove not to be useful then simply place the probe on the forearm and begin the hunt.
A high frequency linear probe is selected and placed near the expected target location. An initial depth of 1-2 cm should suffice, however larger patients may require greater depth. When searching for veins, check the compressibility of the structures with the tourniquet on. This will assist in differentiating small tendons from vessels. It may be easier to use arterial catheters (A-line) for ultrasound guided venous cannulation due to the availability of a guide wire and generally longer shafts. This allows you to breach the vessel at greater depth and maintain it with the wire for cannulation. If performed under sterile technique, a suture may be added for protection against accidental dislodging. The Doppler mode is engaged to show blood flow. This allows providers to have a choice in needle guidance. The long axis view can be easily combined with an in-plane needle technique.
This video shows a long axis view of the cephalic vein while a tourniquet is applied. Note the slow progressive flow of blood as it meanders towards the tourniquet (or cephalad).
This image shows a short axis completed IV catheter in the cephalic vein.
This image shows a long axis view of a patent venous cannulation with active flow of IV fluid. The fluid is seen as turbulent flow at the end of the catheter. A doppler can also be used to help determine if flow is present at the end of the catheter.