What is the difference between a midline catheter and a Peripherally Inserted Central Catheter (PICC) line?

Differences Between Midline Catheters and PICC Lines

Midline catheters and PICC lines differ primarily in their insertion depth, tip location, duration of use, and indications, with PICCs being central venous catheters that terminate in the superior vena cava while midlines remain in peripheral veins. 1

Anatomical Differences

Midline Catheters:

• Length: 7.5 to 25 cm 1
• Insertion site: Above the antecubital fossa in the upper arm
• Tip location: Terminates in the basilic or cephalic vein, short of the subclavian vein 1
• Does not reach central circulation
• Non-tunneled device intended for medium-term access 1

PICC Lines:

• Length: >45 cm in adults 1
• Insertion site: Same as midlines (upper arm peripheral veins)
• Tip location: Terminates in the lower portion of the superior vena cava or upper portion of the right atrium 1
• Provides access to central circulation
• Can be tunneled or non-tunneled 2

Clinical Applications

Midline Catheters:

• Appropriate for peripherally compatible infusates (osmolarity ≤850 mOsm/L) 1
• Preferred for infusion durations of 6-14 days 1
• Cannot accommodate irritant or vesicant infusions 1
• Suitable for patients with difficult venous access when treatment duration is ≤14 days 1
• Can be used for up to 28 days, though evidence is stronger for use ≤14 days 3, 4
• No radiological verification of tip position required after insertion 4

PICC Lines:

• Appropriate for both peripherally compatible and non-compatible infusates 1
• Preferred for infusion durations >15 days 1
• Required for irritants or vesicants (e.g., chemotherapy, parenteral nutrition with high osmolarity) 1
• Suitable for frequent blood sampling (≥3 phlebotomies per day) when duration exceeds 6 days 1
• Can remain in place for months 3
• Requires radiological confirmation of tip position 2

Complication Profiles

Infection Risk:

• Midlines are associated with lower rates of catheter-related bloodstream infections compared to PICCs 5, 6
• Recent randomized clinical trial found extremely low CRBSI rates in both devices with no significant difference 7

Thrombosis Risk:

• Midlines have higher rates of superficial venous thrombosis 5
• PICCs may have lower risk of deep vein thrombosis in time-to-event models 6
• Overall thrombosis risk findings are mixed across studies 5, 7, 6

Mechanical Complications:

• Midlines have higher overall mechanical complication rates in recent RCT data 7
• Catheter occlusion appears more common with PICCs 6
• For catheters used <16 days, complication rates may be similar 7

Selection Algorithm

1. Assess infusate characteristics:

   • Peripherally compatible (osmolarity ≤850 mOsm/L): Either device appropriate
   • Irritant/vesicant medications or TPN with high osmolarity: PICC required 1

2. Determine expected duration of therapy:

   • ≤14 days: Midline preferred 1, 3, 4
   • 15-28 days: Consider PICC, though midlines may be used with caution 1, 3

   • 28 days: PICC required 1

3. Consider frequency of blood draws:

   • Frequent phlebotomy (≥3/day) for >6 days: PICC preferred 1

4. Evaluate patient-specific factors:

   • Chronic kidney disease stage 3-5: Avoid PICC to preserve veins for potential future dialysis access 1
   • Self-care requirements: PICCs may limit use of one arm, affecting patient independence 1

Important Caveats

• Midlines should not be used for administration of vesicants or irritants as they do not provide central venous access 1
• PICCs should be avoided in patients with chronic kidney disease who may need future hemodialysis access 1
• The most recent high-quality RCT (2024) showed higher overall complication rates with midlines, contradicting some earlier observational studies 7
• For very short-term use (<16 days), complication rates between devices may be similar 7
• Patient selection and appropriate catheter choice significantly impact morbidity, mortality, and quality of life outcomes