A nurse is preparing to obtain a blood specimen for a comprehensive metabolic panel from a client's multi-lumen central venous catheter (CVC). A continuous infusion of parenteral nutrition is currently running through an adjacent lumen. To reduce the risk of pre-analytical laboratory errors and maintain line patency, in what order should the nurse perform the following actions? (Arrange the items in the correct chronological sequence.)
- 1Stop the continuous parenteral nutrition infusion.
- 2Cleanse the needleless connector and flush the lumen with 0.9% sodium chloride.
- 3Aspirate and discard the initial 5 mL of blood.
- 4Obtain the required volume of blood for the laboratory specimen.
- 5Flush the catheter with 0.9% sodium chloride and restart the infusion.
Answer
The correct sequence requires the nurse to first halt the continuous infusion, verify patency with a saline flush, clear the dead space of residual fluid by discarding an initial blood volume, collect the pure diagnostic sample, and finally flush the line again before resuming the parenteral nutrition.
Drawing blood from a multi-lumen central venous catheter carries a high risk of pre-analytical laboratory error if the sample is contaminated by concurrent infusions or diluted by flush solutions. Adhering to the standard sequence—pausing adjacent infusions, scrubbing the hub and flushing to confirm patency, utilizing a discard volume to clear dead space, drawing the diagnostic sample, and providing a final flush—ensures highly accurate laboratory data and preserves long-term catheter function.
Step-by-Step Solution
Key Concept
Strict sequential protocols for central venous catheter blood sampling—including pausing infusions and discarding initial waste volumes—are essential to mitigate the risk of pre-analytical laboratory errors and inappropriate clinical interventions.