Flushing and Locking of Venous Catheters: Available Evidence and Evidence Deficit

Table 4

Calculation of recommended locking volumes if lock does not cause adverse effects when systemically injected.

Catheter type	Total lock volume in mL	Minimum catheter volume in mL; (Approximately internal volume + 20% spillage)	Extra volume^a
Peripheral catheters	1.0	0.04 (0.03 + 0.006)	0.9
Midline	1.5	0.5 (0.4 + 0.1)	1.0
PICC	1.5	0.7 (0.6 + 0.1)	0.8
Nontunnelled CVC	1.5	0.7 (0.6 + 0.1)	0.8
Small bore tunnelled catheter (≤1 mm ID)	1.5	0.8 (0.7 + 0.1)	0.7
Large bore tunnelled catheter (>1 mm ID)	2.5	1.6 (1.3 + 0.3)	0.9
TIVADs (reservoir volume up to 0.6 mL)	2.5	1.6 (1.3 + 0.3)	0.9

Volume might be used for add-ons, Huber needle, extension set extra-long catheters, or surplus for the positive pressure technique.