Midline Catheter Flushing Guidelines

Primary Recommendation

Sterile 0.9% sodium chloride (normal saline) should be the standard flush solution for midline catheters, with Grade A evidence supporting this practice for central venous access devices 1
Multiple meta-analyses have concluded that intermittent flushing with heparin provides no additional benefit over normal saline alone for maintaining catheter patency 1
For catheters accessed frequently or closed for short periods (<8 hours), normal saline flushing alone is sufficient 1

Heparinized solutions (5-10 U/mL) may be considered only when specifically recommended by the manufacturer or for open-ended catheter lumens scheduled to remain closed for more than 8 hours 1
If heparin is deemed necessary, use concentrations between 50-500 units per mL, though most authors suggest the lower end of this range 1
For intermittently accessed devices remaining unused for prolonged periods, flushing with 5-10 U/mL heparinized saline 1-2 times weekly can be considered 1

Heparin promotes intraluminal biofilm formation, potentially increasing catheter-related bloodstream infection risk 1
Risks of heparin prophylaxis include thrombocytopenia and bone disease, which presumably outweigh the risk of thrombosis in many cases 2
Heparin should never be used immediately before or after administration of lipid-containing parenteral nutrition, as heparin may facilitate lipid precipitation 1
If heparin must be used after lipid administration, a saline flush must always be interposed between the lipid infusion and heparin 1

The European Society for Clinical Nutrition and Metabolism (ESPEN) explicitly recommends against routine heparin lock, stating saline should be the standard with Grade B recommendation and 95.5% agreement 1

Flush with normal saline using a volume at least twice the catheter volume 2
Use 10 mL or larger syringes to prevent excessive pressure that could damage the catheter 3
Employ turbulent push-pause technique when flushing to create turbulence that helps clear the catheter lumen 3
Maintain strict aseptic technique during all catheter access 1

First attempt: forceful irrigation with saline, which will unclog the catheter in many cases 2
If saline fails: use fibrinolytic drugs (urokinase or alteplase) for thrombotic occlusions with at least 30 minutes dwell time 2
Non-thrombotic occlusions should be treated according to their etiology (lipid occlusion with 70% ethanol, mineral precipitates with 0.1 N HCl) 2