Final answer:
The tourniquet should be released immediately after a "flashback" of blood is observed during the insertion of a peripheral intravenous device, confirming needle entry into the vein.
Step-by-step explanation:
The tourniquet should be released during the procedure for insertion of a peripheral intravenous device immediately after observing a "flashback" of blood in the catheter. This is a critical step in IV insertion because the appearance of blood in the flashback chamber confirms that the needle has entered the vein. At this point, the needle is slightly advanced further in the vein, and then the tourniquet is released. Releasing the tourniquet after the flashback but before advancing the catheter off the needle ensures proper catheter placement without excessive pressure that might cause damage to the vein.
Once the tourniquet is released, the clinician can continue to insert the catheter into the vein and secure it properly. The timing of the release is essential to preventing complications and promoting comfort during intravenous therapies.