What are the recommended flushing protocols for pediatric patients with ports to minimize blood waste?

Wasting Protocols for Blood Draws from Ports in Pediatric Patients

Recommended Waste Volume

For pediatric patients, withdraw 3 to 5 mL of blood as waste according to the fill volume of the catheter before drawing the diagnostic sample. 1

This recommendation comes from the NKF-K/DOQI guidelines, which specifically address pediatric catheter blood sampling and acknowledge that pediatric patients and their catheters are smaller, requiring reduced volumes compared to the adult standard of 10 mL. 1

Step-by-Step Blood Draw Protocol

Initial Preparation

• Withdraw any heparin and saline from the port first, following your institution's protocol to prevent dilution of the blood sample. 1
• Use sterile technique throughout the procedure. 1

Waste Volume Withdrawal

• Withdraw 3 to 5 mL of blood based on the catheter's fill volume (this is the "waste" volume). 1
• Do not discard this blood immediately if you plan to reinfuse it after sampling is complete—this minimizes blood loss in pediatric patients. 1
• The purpose of this waste volume is to ensure the diagnostic sample will not be diluted by residual heparin or saline, providing an additional margin of security beyond the initial flush removal. 1

Diagnostic Sample Collection

• Connect a new syringe or collection device and draw the diagnostic sample for laboratory testing. 1
• This sample is now free from contamination by lock solutions. 1

Optional Reinfusion

• Consider reinfusing the initial waste blood (from step 2) to minimize blood loss, particularly important in smaller pediatric patients. 1

Critical Technique Points

Preventing Sample Contamination

• Never draw a diagnostic sample if saline or heparin is present in the lines, as this will artificially dilute laboratory values. 1
• The waste volume must be adequate to clear all lock solution from the catheter lumen. 1

Port Maintenance After Blood Draw

• Flush with 5-10 mL normal saline after blood sampling using a turbulent push-pause technique. 2, 3
• For ports accessed intermittently, lock with 5-10 U/mL heparinized saline 1-2 times weekly to maintain patency. 1
• For ports in daily use, saline alone is sufficient without heparin. 1, 2

Common Pitfalls to Avoid

Inadequate Waste Volume

• Using insufficient waste volume (less than 3 mL in pediatrics) risks contaminating the diagnostic sample with lock solution, leading to falsely abnormal laboratory results. 1

Excessive Blood Waste

• While adult protocols recommend 10 mL waste, this volume is excessive for pediatric patients and contributes to iatrogenic anemia. 1
• Always adjust waste volume to the catheter fill volume rather than using a fixed adult protocol. 1

Improper Flushing Sequence

• Always flush with saline BEFORE heparinization, as saline flushing is more important than the heparin lock itself. 2
• Never use heparin immediately before or after lipid-containing infusions due to precipitation risk. 2

Special Considerations

Catheter Size Matters

• Smaller catheters in younger children require proportionally smaller waste volumes (closer to 3 mL). 1
• Larger pediatric catheters may require up to 5 mL waste. 1

Infection Prevention

• Disinfect catheter connectors, ports, and hubs before accessing, preferably with 2% chlorhexidine solution in 70% isopropyl alcohol. 1
• However, avoid chlorhexidine in infants younger than 2 months due to potential side effects. 1
• Appropriate hand hygiene must be performed before accessing the port. 1

When Blood Return Is Absent

• If you cannot withdraw the waste volume due to absent blood return but the port flushes easily, this may indicate partial occlusion or fibrin sheath formation. 4
• Use recombinant tissue plasminogen activator or urokinase to restore patency before attempting blood draws. 1, 4
• The port can still be used for infusions while troubleshooting blood return issues. 4