Five studies were included in the review: one randomised controlled trial (RCT; (n=5,037), two double-blind quasi-experimental studies (number of participants not reported) and two quasi-experimental studies (n=276).
A formal validity assessment was not carried out. However, the author identified methodological limitations in all of the studies including: use of outcome measures that were not established as valid or reliable; lack of randomisation or blinding; insufficient power or lack of power analysis; inadequate description of study details or outcome criteria; and failure to control for confounding variables such as differences between nursing staff.
Four of the five studies, including the RCT, concluded that heparinised solutions increased the patency of arterial catheters in comparison with non-heparinised solutions. Statistical significance (p-values) was only reported for two of these studies (one was significant, p<0.05; the other was not significant, p=0.06). One quasi-experimental study concluded that non-heparinised arterial catheters could be maintained in short-term catheter placement (no statistical data or p-values were provided).