The nurse is precepting a student nurse on the postsurgical floor. The student nurse needs to draw a potassium level. Which of the following statements by the student nurse is correct regarding blood draws from venous catheters?

  • “I can obtain the sample from the short peripheral catheter if I flush it well.”
  • “I should flush with 10 to 20 mL of sterile normal saline after drawing blood from any catheter.”
  • “Drawing blood from a central venous line is less risky than sticking the client if he is afraid of needles.”
  • “I should use a syringe with a large needle to transfer blood into the test tube to avoid hemolyzing the sample.”
Number 2 is correct.
Flushing the catheter with 10 to 20 mL of sterile normal saline is necessary to ensure a patent line. Short peripheral catheters should not be used for routine blood sampling because manipulation can cause vein irritation and necessitate removal of the catheter. Obtaining blood samples from central venous lines carries a much greater risk of infection and may interfere with test results depending on the types of fluids that have been infused recently. Transferring blood into test tubes should be done without using exposed needles, for example, by using a vacutainer system.