A useful approach to verifying vein patency is called the wipe technique. Properly used, this can help you verify blood flow in the selected vein and show you where any valves might be.
The general idea is that by pushing the blood out of the vein, it will disappear from the projection. When you allow the blood to return to the vein it will refill and then reappear in the projection. The device detects the hemoglobin in the blood that’s filling the vein, not the vein itself. That’s why this works.
A useful approach to verifying vein patency is called the wipe technique. Properly used, this can help you verify blood flow in the selected vein and show you where any valves might be.
The general idea is that by pushing the blood out of the vein, it will disappear from the projection. When you allow the blood to return to the vein it will refill and then reappear in the projection. The device detects the hemoglobin in the blood that’s filling the vein, not the vein itself. That’s why this works.