title: Normal saline versus heparin for patency of central venous catheters in adult patients - a systematic review and meta-analysis.
abstract: BACKGROUND
  Heparin saline (HS) is theoretically superior to normal saline (NS) for maintaining the patency of central venous catheters (CVCs), but the comparative efficacy of them remains controversial. The aim of this systematic review and meta-analysis was to assess the efficacy of NS versus HS in the maintenance of the patency of CVCs in adult patients.
  
  
  METHODS
  We searched PubMed, Embase and the Cochrane library databases. Randomized controlled trials (RCTs) evaluating the use of NS vs. HS to maintain the permeability of CVCs among adult patients were included in our meta-analysis. References of relevant papers were reviewed manually. No language restriction was applied. Non-human studies were excluded. Pooled relative risk (RR) was calculated using a Mantel-Haenszel random-effects model. We also performed subgroup analysis examining the effect of the duration of catheter placement on the outcome. All statistical tests were two-sided using a significance level of 0.05.
  
  
  RESULTS
  Ten RCTs involving 7875 subjects (with analysis at patient, catheter, lumen and line access level) were included in this meta-analysis. Whether in terms of pooled or local analysis (RR with 95% confidence interval spans 1), NS can be equally, if not more effective, in keeping the CVCs open. Of studies reporting secondary outcomes (maneuver needed, heparin-induced thrombocytopenia, haemorrhage, central venous thrombosis and catheter-related bloodstream infection), heparinised saline was shown not to be superior to non-heparinised solution. Subgroup analysis in patients with short vs long term CVC placement was consistent with the main outcome partly and in particular for maintenance of catheter patency in patients with a long-term placement i.e. >30 days, the RR was 0.97 (n = 6589; 95% CI = 0.76 to 1.23; P = 0.796). However, for patients in whom the catheter was in place for <30 days, the RR was 1.52 (n = 1286; 95% CI = 1.02 to 2.27; P = 0.041).
  
  
  CONCLUSIONS
  Based on the results of this meta-analysis, HS is not superior to NS in reducing CVCs occlusion. But in the short term, the use of HS is slightly superior to NS for flushing catheters from a statistical point of view.
authors.affiliation: Department of Intensive Care Units, The First Affiliated Hospital of Jinzhou Medical University, No. 2, The Fifth Section of Renmin Street, Guta, Jinzhou, 121000, Liaoning, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhong
authors.affiliation: Department of Obstetrics and Gynaecology, The First Affiliated Hospital of Jinzhou Medical University, Jinzhou, 121000, Liaoning, China.
authors.forename: Hai-Li
authors.initials: HL
authors.lastname: Wang
authors.affiliation: Department of Intensive Care Units, The First Affiliated Hospital of Jinzhou Medical University, No. 2, The Fifth Section of Renmin Street, Guta, Jinzhou, 121000, Liaoning, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Xu
authors.affiliation: Jinzhou Medical University, Jinzhou, 121000, Liaoning Province, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Xinxiang Medical University, Xinxiang, 453000, Henan Province, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Intensive Care Units, The First Affiliated Hospital of Jinzhou Medical University, No. 2, The Fifth Section of Renmin Street, Guta, Jinzhou, 121000, Liaoning, China.
authors.forename: Ying-Ying
authors.initials: YY
authors.lastname: Zhang
authors.affiliation: Department of Intensive Care Units, The First Affiliated Hospital of Jinzhou Medical University, No. 2, The Fifth Section of Renmin Street, Guta, Jinzhou, 121000, Liaoning, China.
authors.forename: Li
authors.initials: L
authors.lastname: Ji
authors.affiliation: Department of Intensive Care Units, The First Affiliated Hospital of Jinzhou Medical University, No. 2, The Fifth Section of Renmin Street, Guta, Jinzhou, 121000, Liaoning, China.
authors.forename: Zi-Mu
authors.initials: ZM
authors.lastname: Pan
authors.affiliation: Department of Intensive Care Units, The First Affiliated Hospital of Jinzhou Medical University, No. 2, The Fifth Section of Renmin Street, Guta, Jinzhou, 121000, Liaoning, China. icugroup@sina.com.
authors.forename: Zhan-Sheng
authors.initials: ZS
authors.lastname: Hu
mesh_terms: D000328:Adult; D061807:Catheter Obstruction / Q000009:adverse effects; D062905:Central Venous Catheters; D006493:Heparin / Q000008:administration & dosage* / Q000627:therapeutic use; D006801:Humans; D012965:Sodium Chloride / Q000008:administration & dosage* / Q000627:therapeutic use; D007507:Therapeutic Irrigation / Q000379:methods* / Q000592:standards*; D013927:Thrombosis / Q000188:drug therapy / Q000517:prevention & control
chemical_list: D012965:Sodium Chloride; D006493:Heparin
keywords: Central venous catheters; Heparin; Normal saline; Occlusion