Outcome measures
Arterial catheter utility was measured differently amongst the studies. Four studies used survival analysis (hours) without the log rank data (clarity of censored data) available for statistical comparison of how the different studies relate to each other; two studies used the mean (min/h) duration of catheter in place and one study used the mean duration of catheter survival against the central limits theorem at the 95% CI . All of the included studies, except for Goh 2011, assessed catheter functionality by counting one or all of the following events within a specified period: arterial haemodynamic waveform dampening, resistance to manual flushing or blood withdrawal from the arte- rial cannula and the need for manipulation of the arterial catheter (position change, etc). Tuncali 2005 was the only study that reported assessment of the secondary outcomes of interest: risk of haematoma, insertion site infection and limb ischaemia. Budz 1995 was the only study that assessed the presence of clots on the arterial catheter upon removal. Although five of the included studies monitored participant coagulation profiles throughout the trial-prothrombin time, partial thromboplastin time and platelet count-no comparative analysis on risk of bleeding was performed