A total of seven studies (606 participants) met the inclusion criteria and measured the primary outcome of interest. All studies were
at unclear to high risk of bias. Given the high degree of clinical and statistical heterogeneity of the included studies, no meta-analysis
was completed. The results from individual studies that compared heparin at a dose of 1 to 2 IU/mL under continuous pressure were
imprecise and do not provide definitive evidence of a difference. The observed difference with a dose of heparin increased to 4 IU/
mL came from only one study of 30 participants, and the quality of the reported data was poor. Similarly. consistency in assessment
and reporting of adverse events such as haematoma, insertion site infection and limb ischaemia was poor. Further research with welldefined
primary and secondary outcome measures using a stratified sampling process that accommodates for the different heparin doses
commonly used in clinical practice is needed to confirm the trends seen in research results now reported in the literature.