Is it best practice to draw blood samples from peripheral intravenous (IV) lines?

From the Guidelines

Drawing blood samples from peripheral IVs is not the best practice due to the risk of hemolysis and contamination with IV fluids or medications, which can lead to inaccurate laboratory test results. When considering the best approach for drawing blood samples, it is essential to prioritize methods that minimize the risk of contamination and ensure accurate laboratory results. According to the study published in Critical Care in 2013 1, the first option for blood sampling in critically ill adults should be from an arterial catheter, followed by a venous catheter if the arterial catheter is unavailable. Some key points to consider when drawing blood samples include:

• The risk of hemolysis and contamination with IV fluids or medications when drawing from peripheral IVs
• The importance of maintaining sterility and avoiding contamination of the sample by flush solution when drawing from venous catheters
• The need to clearly label specimens drawn from IV lines to ensure accurate interpretation of laboratory results
• The recommendation to use direct venipuncture as the gold standard for blood collection, as it provides the most accurate and reliable laboratory results. In clinical practice, it is recommended to avoid drawing blood samples from peripheral IVs whenever possible, and instead use direct venipuncture or draw from arterial or central venous catheters. If drawing from a peripheral IV cannot be avoided, precautions such as flushing the line with saline and discarding the first 5-10 mL of blood should be taken to minimize the risk of contamination and hemolysis.

From the Research

Blood Sampling from Peripheral IVs

• Blood samples taken from used peripheral intravenous cannulae can be clinically interchangeable with venepuncture for certain tests, including sodium, chloride, urea, creatinine, and haematology samples 2.
• However, limits of agreement for potassium samples from used peripheral intravenous cannulae exceeded the clinically acceptable range, with a limit of ±0.47 mmol/L 2.
• Blood gas analysis samples from peripheral intravenous cannulae should not be used, as the limits of agreement far exceeded the clinically acceptable range 2.
• A systematic review with meta-analysis found no significant difference in haematology, blood chemistry, and coagulation test values between blood samples taken via venipuncture and peripheral venous catheter 3.
• Using 5-mL collection tubes instead of 10-mL tubes can reduce the risk of hemolysis when drawing blood samples from IV catheters 4.

Considerations for Clinical Practice

• Blood sampling from used peripheral intravenous cannulae can be a reasonable clinical practice for haematology and biochemistry samples, but potassium samples should be used with caution 2.
• Healthcare providers may refer to more reliable laboratory results when using peripheral venous catheters for blood sampling, reducing the need for frequent venipuncture and associated risks 3.
• Nurses should follow best practices for safe management and prevention of catheter-associated bloodstream infections related to peripheral intravascular line placement 5.