The arm (from the elbow to the axillary cavity) can be divided into three bands of similar size, corresponding to the proximal third (yellow area of Dawson), the middle third (Dawson's green zone) and the distal third (Dawson's red zone).
The international recommendations consider the exit site located in the green zone (both in terms of stability and in terms of risk of bacterial contamination) most appropriate. If in the green zone there is not a suitable vein in terms of caliber and depth, it is nonetheless possible to puncture and cannulate a vein in the yellow zone (probably with a larger diameter since it is more proximal) and tunnel the catheter until it exits in the green zone.