Attributes of good vein for cannulation?

1. Straightness: Look for a vein that is relatively straight and not too tortuous. This will make it easier to insert the needle and reduce the risk of complications.

2. Size: The vein should be large enough to accommodate the needle without causing too much pain or discomfort.

3. Palpability: The vein should be easy to feel by touch. This will help you locate the vein and ensure that you are inserting the needle in the right place.

4. Location: Avoid veins that are located in areas where they could be easily compressed, such as the antecubital fossa. These veins are more likely to collapse when the needle is inserted, making it difficult to draw blood or administer fluids.

5. Color: The vein should be blue or green in color. Avoid veins that are red or swollen, as these may indicate inflammation or infection.

6. Patient factors: Consider the patient's age, medical history, and any medications they are taking that could affect vein health.