Which action increases the risk of contamination when changing IV tubing?

When changing IV tubing, disconnecting the old tubing and touching the new adapter significantly increases the risk of contamination. This is because touching the new adapter can introduce pathogens from your hands or the surrounding environment directly onto a critical connection point. The integrity of the sterile technique is paramount in IV therapy, as any contamination at this stage could lead to serious complications such as infection.

In contrast, changing the primary intermittent tubing after 24 hours is a standard practice intended to minimize the risk of infection from prolonged use. Wiping the port with an alcohol swab is a necessary step to disinfect surfaces before connecting new lines, which helps reduce the potential for contamination. Flushing the vascular access device with saline is an important procedure for maintaining patency and does not inherently increase the risk of contamination when performed correctly. Thus, option A clearly stands out as the action that most directly impacts the sterility of the infusion system.