1. Singh Joy, Subhashni D.
  2. Kayyali, Andrea MSN, RN

According to this study:

* Needleless central catheter caps should be changed before blood sampling.


* Taking blood samples with the old cap in place led to a high rate of false-positive results for bacteremia and, therefore, to unnecessary treatment.



Article Content

Central catheters are essential and common tools in hospitals; however, they can also be a source of bloodstream infections. This study examined the relationship between needleless catheter connectors (catheter caps) and infection. A total of 91 patients (median age, 61 years) receiving long-term acute care at one specialty rehabilitation facility were included in the study. The patients had either peripherally inserted central catheters (83 patients) or triple-lumen catheters (8 patients). Nurses drew blood samples on the same day using three different methods: drawing with the existing (old) central catheter cap in place, drawing after the old cap had been replaced with a new one, and by peripheral venipuncture.


Analysis of the blood samples yielded positive culture results in 18 patients using the new cap, 36 using the old cap, and 10 using peripheral venipuncture. The new-cap method provided the most accurate results; all 18 patients identified by this method were true positives. In contrast, only 17 of the 36 identified by the old cap method were true positives, and all 10 identified by peripheral venipuncture were true positives (although, notably, eight true positives were missed). Analysis of blood drawn after the change to a new cap accurately identified 73 negative samples; analysis of blood drawn through the old cap and through peripheral venipuncture correctly identified 54 and 73 negative samples, respectively.


Accessing blood from the old cap resulted in a high rate (53%) of false-positive test results. Because the physicians were blinded to study results, the facility's usual protocol was followed and patients with false-positive results received unnecessary systemic antibiotics and had their central catheters replaced.


These results support the practice of changing catheter caps before taking blood samples. It can result in more accurate diagnosis of bacteremia, thereby reducing the use of unnecessary antibiotics, decreasing hospital and patient costs, avoiding unnecessary trauma to patients, and improving patient outcomes.




Mathew A, et al. J Infus Nurs 2009;32(4):212-8.