What is the necessary first step when preparing a patient for IV insertion?

The first and necessary step when preparing a patient for IV insertion is to apply a tourniquet 4 to 6 inches above the selected site. This action serves to engorge the veins, making them more prominent and easier to access, which is crucial for successful catheter placement. The engorgement occurs due to the restriction of venous blood flow, enhancing visibility and palpability of the veins. This step is fundamental as it directly influences the ease of IV insertion and helps to minimize patient discomfort as well.

Once the tourniquet is in place, further preparations can follow, such as cleaning the insertion site and eventually securing the IV after placement. However, without the effective application of a tourniquet first, the subsequent steps may be more challenging and less effective.