What is the indication for a midline (peripherally inserted central catheter)?

Indications for Midline Catheters

Midline catheters are most appropriate for patients requiring intermediate-duration intravenous therapy (6-14 days) with peripherally compatible infusates, offering lower complication rates compared to PICCs while providing more durable access than peripheral IVs. 1

Primary Indications for Midline Catheters

Based on Duration of Therapy

• 6-14 days of therapy: Midlines are the preferred device for peripherally compatible infusates in this timeframe 1, 2
• <6 days: Standard peripheral IV or ultrasound-guided peripheral IV is more appropriate 1
• >14 days: PICC lines become more appropriate due to potential midline failure beyond this period, though midlines may be used for up to 4 weeks 1

Based on Type of Infusate

• Peripherally compatible infusates (pH 5-9, osmolarity <500 mOsm) 3:

  • Antibiotics with low irritant potential
  • IV fluids that would normally be administered through a peripheral IV
  • Medications that don't require central venous access

• NOT appropriate for:

  • Irritants or vesicants (e.g., chemotherapy, parenteral nutrition) 1
  • Solutions with pH <5 or >9 3
  • Solutions with osmolarity >500 mOsm 3

Special Clinical Scenarios

• Difficult venous access: Preferred over PICCs when access is needed for ≤14 days 1
• Frequent phlebotomy (≥3 per day): Appropriate for durations of ≤14 days 1
• Antibiotic administration: Suitable for antibiotics including vancomycin and cefepime when treatment duration is <14 days 2

Patient Population Considerations

Critical Care Patients

• Appropriate for peripherally compatible infusates with expected duration of 6-14 days 1
• Recent studies show favorable outcomes and cost savings in critical care settings 1

Cancer Patients

• Appropriate for durations ≤14 days when the indication is frequent phlebotomy or difficult venous access 1
• Not appropriate for chemotherapy administration (irritant/vesicant) 1

Patients with Chronic Kidney Disease

• Contraindicated in CKD stage 3b or greater (eGFR <45 mL/min) to preserve veins for potential future hemodialysis access 1, 2

Patients in Skilled Nursing Facilities

• Appropriate for peripherally compatible infusions when duration is expected to be 6-14 days 1
• Suitable for antibiotic administration in this setting 2

Advantages of Midline Catheters

• Lower rates of bloodstream infection compared to PICCs (0.4% vs 1.6%) 4
• Lower rates of occlusion than PICCs (2.1% vs 7.0%) 4
• No need for chest X-ray confirmation of placement 3
• Lower rates of phlebitis than short peripheral IVs 3
• More cost-effective than serial peripheral IVs for therapies lasting approximately 6 days or longer 5
• Higher completion rates for prescribed therapy compared to peripheral IVs 6

Placement Considerations

• Typically placed in upper arm veins (brachial or cephalic) 3
• Distal tip ends below the level of the axillary line 3
• Placement in cephalic or deep basilica veins provides more blood flow, reducing risk of mechanical or chemical phlebitis 3
• Can be inserted using ultrasound-guided Seldinger technique 3

Caution and Contraindications

• Mixed evidence regarding DVT risk compared to PICCs 4
• Not suitable for patients requiring central venous access
• Not appropriate for infusion of irritants or vesicants 1
• Avoid in patients with CKD stage 3b or greater 1, 2
• Regular monitoring for complications including infiltration, phlebitis, occlusion, and infection is essential 2

Midline catheters represent an important intermediate option between short peripheral IVs and PICCs, filling a critical gap in vascular access options while potentially reducing complications associated with central venous access devices when used for appropriate indications.