REVIEW QUESTION

Is intermittent locking with heparin or normal saline safer and more effective in the prevention of central venous catheter (CVC) occlusion?

TYPE OF REVIEW

A systematic review of 11 randomized controlled trials (RCTs).

RELEVANCE FOR NURSING

CVCs commonly provide iv access for critically ill patients-yet they are not without risk. There is the possibility of thrombosis following CVC insertion, for example, which is a significant cause of morbidity and mortality, increasing the risk of blockage, infection, and pulmonary embolism. Consequently, when CVCs are not in use, intermittent locking (filling the lumens) with normal saline or unfractionated heparin is often used to maintain catheter patency. There are widespread differences in nursing practice, however, regarding locking frequency and the use of heparin versus normal saline. Thus, an examination of the effectiveness of heparin versus normal saline in intermittent CVC locking in adults is warranted.

CHARACTERISTICS OF THE EVIDENCE

A total of 11 RCTs of CVC locking in adults (a total of 2,392 participants) using heparin (any dose, with or without systemic drugs) versus normal saline were included in the review. There was heterogeneity across the trials due to variations in procedural methods and in heparin concentrations (10 to 5,000 IU/mL), the unit of analysis used (participant, catheter, line access), and time to follow-up (1 to 251.8 days).

Primary outcome measures were the occlusion of CVCs and the duration in days of catheter patency. Secondary outcome measures included episodes of CVC-related sepsis, mortality rates, hemorrhage anywhere in the body, heparin-induced thrombocytopenia (HIT), CVC-related thrombosis, and the abnormality of the coagulation profile.

Regarding the primary outcome, combined results of 10 studies showed fewer occlusions with heparin than with normal saline (very-low-quality evidence), but pooled results of six studies showed no clear differences between heparin and normal saline in the duration of catheter patency (low-quality evidence). Among the secondary outcomes, there were no clear differences between heparin and normal saline in episodes of CVC-related sepsis in two studies, mortality rates in three studies, hemorrhage anywhere in the body in four studies, HIT in three studies, and CVC-related thrombosis in three studies.

One study investigated the abnormality of coagulation profiles, finding significantly higher parameters in the heparin group for activated coagulation time and activated partial thromboplastin time. Prothrombin time was also elevated in the heparin group, but the difference between groups was not significant.

BEST PRACTICE RECOMMENDATIONS

The results of this review suggest that, in adults, locking of CVCs with heparin may result in fewer occlusions than locking with normal saline, but the use of heparin may have little or no effect on the duration of CVC patency. These results should be interpreted with caution, however, because of the generally very low quality of the evidence.

RESEARCH RECOMMENDATIONS

Better-designed, large-scale RCTs are needed to definitively establish a net benefit of locking with heparin versus normal saline; these trials should also explore effectiveness in different patient groups, such as those under hemodialysis and those with hematologic malignancies. Occlusions and adverse events should be the focus of future trials, and assessment by type of line (such as dialysis/apheresis versus peripherally inserted central catheter or another type) is important.

REFERENCE