From the Guidelines
Yes, blood can be drawn from a midline catheter, but it is not the preferred method for routine blood draws. Midline catheters are peripheral intravenous access devices that are typically 8-20 cm in length and placed in veins of the upper arm, with the tip residing in the basilic or cephalic vein. When blood collection from a midline is necessary, proper technique is essential to prevent contamination and inaccurate results. The procedure requires flushing the line with normal saline, discarding the first 5-10 mL of blood as waste to avoid dilution from the flush solution, and then collecting the sample. After collection, the line must be flushed again with saline to maintain patency. Blood draws from midlines should be limited because frequent manipulation increases infection risk and may shorten the catheter's lifespan. Additionally, certain laboratory tests, particularly coagulation studies and drug levels, may be affected by drawing from vascular access devices. For most patients, venipuncture from a peripheral vein remains the gold standard for blood collection due to reduced risk of contamination and more reliable test results 1.
Some key points to consider when using midline catheters for blood draws include:
- Proper technique is essential to prevent contamination and inaccurate results
- Flushing the line with normal saline and discarding the first 5-10 mL of blood as waste is necessary to avoid dilution from the flush solution
- Blood draws from midlines should be limited to minimize infection risk and prolong catheter lifespan
- Certain laboratory tests may be affected by drawing from vascular access devices, and alternative methods may be preferred in these cases
- Venipuncture from a peripheral vein is generally the preferred method for blood collection due to its reliability and lower risk of contamination 1.
It's also important to note that midline catheters can be used for peripheral parenteral nutrition (PN) when the expected duration of therapy is 6-14 days, and they are preferred over PICCs for this interval due to lower risk of complications 2. However, the use of midline catheters for blood draws should be carefully considered and weighed against the potential risks and benefits.
From the Research
Drawing Blood from Midline Catheters
- Midline catheters can be used for blood withdrawal, with studies showing low rates of hemolysis, ranging from 0.69% 3.
- The use of midline catheters for blood sampling is a common practice, with one study finding that more than half of the patients had blood specimens drawn through their midline catheter 3.
- The dwell time for midline catheters used for blood withdrawal is longer compared to those not used for blood withdrawal, with a mean dwell time of 127.19 ± 109.13 hours 3.
Complications Associated with Midline Catheters
- Midline catheters are associated with a higher risk of superficial venous thrombosis compared to peripherally inserted central catheters (PICCs) 4, 5.
- However, midline catheters may have a lower risk of catheter-related bloodstream infection and occlusion compared to PICCs 6.
- The risk of deep vein thrombosis (DVT) associated with midline catheters is unclear, with some studies suggesting a higher risk 5 and others finding no significant difference 6.
Clinical Implications
- The use of midline catheters for blood withdrawal and other purposes requires careful consideration of the potential complications and benefits.
- Healthcare professionals should be aware of the varying practices and techniques for blood sampling from midline catheters, as well as the need for further research to determine best practices 3.
- The selection of midline catheters or PICCs should be based on individual patient needs and characteristics, taking into account the potential risks and benefits of each option 4, 6.