Final answer:
The primary purpose of using surgical asepsis for central venous catheter care is to prevent sepsis by maintaining a sterile field and preventing bloodstream infections.
Step-by-step explanation:
The primary purpose for a nurse to use surgical asepsis when preparing to flush and change the dressing on a patient's central venous catheter is to prevent the introduction of microbes into the patient's bloodstream, which could lead to a potentially life-threatening infection known as sepsis. Venous catheters can easily become common sites for bloodstream infections, and with up to 80,000 catheter-related bloodstream infections occurring annually in the US, the risk of death from such infections is significant. Therefore, maintaining a sterile field and using aseptic techniques is essential in these medical procedures to prevent the contamination of sterile surfaces and protect patients from the dire consequences of infection.