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Normal Saline Versus Heparin for Patency of Central Venous Catheters in Adult Patients – a Systematic Review and Meta-Analysis
Zhong L, Wang HL, Xu B, et al. Crit Care. 2017;21:3.
Study Question: Does normal saline (NS) compared to heparin sodium (HS) have similar efficacy for maintaining the patency of central venous catheters?
Study Description: This was a systematic review and meta-analysis including only randomized controlled trials of NS vs. HS flushing in adults. The review was conducted according to preferred reporting items for systematic reviews and meta-analysis (PRISMA) guideline. Catheter occlusion was the primary outcome.
Results: A total of 10 eligible studies (7,875 patients) were included, consisting of four ICU and six non-ICU studies during 2002-2015. The concentrations of heparin ranged from 10 to 5,000 units/mL. The pooled analysis of the primary outcome did not show any difference between NS and HS (RR 1.21, 95% CI 0.91-1.61, p = 0.186). Seven studies evaluated the duration of catheter placement for 30 days or less and three evaluated for more than 30 days. For long-term efficacy, NS was equally efficacious to HS solution (n = 6,589, RR 0.97, 95% CI 0.76-1.23, p = 0.796). In contrast, NS was less effective for short-term use (n = 1,286, RR 1.52, 95% CI 1.02-2.27, p = 0.041).
Conclusion: HS did not show to be superior to NS in reducing central venous catheter occlusions. However, when evaluated for short term use in a subgroup analysis, HS was more efficacious than NS.
Perspective: Although HS is widely used to maintain central venous catheter patency, the findings of this meta-analysis suggest that NS may have a role in those patients who have long term catheters placed. NS offers the advantage of a lower bleeding risk and avoids the potential for heparin induced thrombocytopenia. Future well-designed studies should evaluate catheter type, heparin concentration and volume, puncture site, frequency of flushing, retention time, and any patient specific confounders.