There were 13 RCTs of peripheral venous catheters (at least 2,120 participants) and 2 RCTs of peripheral arterial catheters (5,169 participants).
Duration of catheter patency (6 venous catheter studies):
Data were not pooled due to differences in reporting. One study looked at using 10 U every 6 hours and one using 100 U every 8 hours, neither showed any significant difference between the two study groups. Of the four studies using a 1 U/mL infusion, two reported statistically significant (P<0.05) differences in the heparin-treated patients as compared to a non-heparin control, both showing an increase (32.6 hours and 54.0 hours) in the duration of catheter patency.
Catheter-related phlebitis (12 venous catheter studies):
Venous catheter (3 studies of 10 U 8- or 12-hourly heparin) RR=1.09, 95% CI: 0.77, 1.52.
Venous catheter (2 studies of 100 U 6- or 8-hourly heparin) RR=0.61, 95% CI: 0.42, 0.88.
Venous catheter (7 studies of 1 U/mL infusion of heparin) RR=0.55, 95% CI: 0.39, 0.77.
Catheter thrombus formation (4 venous catheters studies and 2 arterial catheter studies):
Venous catheter (2 studies of 10 U 8-hourly heparin) RR=1.08, 95% CI: 0.55, 2.10.
Venous catheter (2 studies of 100 U 6- or 8-hourly heparin) RR=0.52, 95% CI: 0.33, 0.83.
Arterial catheter (2 studies including all regimens) RR=0.51, 95% CI: 0.42, 0.61.
Infusion failure (5 venous catheter studies):
Venous catheter (2 studies of 10 U 8-hourly heparin) RR=1.07, 95% CI: 0.80, 1.43.
Venous catheter (3 studies of 1 U/mL infusion of heparin) RR=0.88, 95% CI: 0.72, 1.07.
Quality of studies:
Twelve (out of 13) peripheral venous catheter studies were double blinded and the remaining study was not blinded. One of the two peripheral arterial catheter studies was double blinded and the other was not blinded. Seven (out of 13) peripheral venous catheter studies and one of the two peripheral arterial catheter studies did not exclude any participants from the analysis post-randomisation. The percentage of participants excluded in the remaining studies varied from 2% to 34%, with most excluding less than 10% of participants.