A butterfly needle, or winged infusion set, is a specialized device used for venipuncture and intravenous access when a standard straight needle is not practical. It includes a short, small-gauge hypodermic needle permanently attached to clear, flexible tubing. Flanking the needle are two flexible plastic “wings” that a clinician holds to gain precise control during insertion. The tubing allows the collection tube or syringe to be positioned away from the insertion site, minimizing movement and providing a secure connection. Healthcare providers select this system for short-term procedures when precision and stability are required due to the patient’s condition or the vein site characteristics.
Specialized Patient Needs
A patient’s physical or systemic health status often dictates using a butterfly needle over a conventional one. Pediatric patients frequently require this approach because their veins are smaller and more challenging to stabilize. The smaller needle gauge, often 23 or 25, coupled with the flexible tubing, significantly reduces the likelihood of damaging these delicate vessels or causing vein collapse. The winged design allows the phlebotomist to achieve greater accuracy and control, which is essential when dealing with patients who may have difficulty remaining perfectly still.
Geriatric patients, or those with chronic conditions like cancer or kidney disease, benefit from this device due to compromised vein integrity. Repeated venipuncture, dehydration, or chemotherapy can cause veins to become fragile, superficial, and prone to rupture. The gentler, shallower angle of insertion permitted by the butterfly needle’s design minimizes trauma to these vulnerable veins. The ability to collect blood or deliver medication with less pressure through the tubing helps preserve the vein’s structure, reducing the risk of a hematoma or infiltration.
Accessing Difficult or Fragile Veins
The characteristics of the target vein are a primary determinant for using a winged infusion set. Veins that are small or lie very close to the surface of the skin require the precision offered by the butterfly needle’s short length and shallow insertion angle. The wings provide a stable platform, allowing the clinician to guide the needle tip accurately into vessels that might otherwise be missed or perforated by a longer, stiffer needle.
The butterfly system is advantageous for “rolling veins,” which move away from the needle tip upon contact. Using the wings, the clinician can anchor the vein more effectively against the underlying tissue during penetration. This stabilization ensures the needle enters the vessel lumen correctly, preventing the vein from slipping out of the pathway.
When venipuncture must be performed in difficult locations, such as the veins on the back of the hand or wrist, the flexible tubing is helpful. The tubing allows the collection device to be held at an awkward angle or distance, providing better ergonomics for the phlebotomist while maintaining a secure needle placement. This design enables access to sites that would be nearly impossible to manage with a rigid, straight needle and tube holder.
Limitations in High-Volume Procedures
Despite their utility for difficult access, butterfly needles are not the preferred tool for procedures involving rapid, high-volume fluid transfer. The small internal diameter of the needle and the flexible tubing restricts the rate of flow, making them inefficient for administering large bags of intravenous fluids quickly or for emergency blood transfusions. A standard intravenous catheter or a larger-bore straight needle is typically chosen in these scenarios to ensure faster delivery rates.
The narrow gauge of the needle poses a risk when drawing blood samples for certain laboratory tests. Needles smaller than 23 gauge, such as a 25-gauge, can increase the shear stress on red blood cells as they pass through the restricted opening. This can lead to hemolysis, which contaminates the sample and causes inaccurate test results. While a 23-gauge needle is considered safe, the potential for hemolysis must be considered when collecting multiple tubes or when the sample must be drawn rapidly.
Butterfly needles are designed for short-term use, such as a single blood draw or a brief infusion. They are less suitable for long-term indwelling use, such as continuous IV drips lasting many hours or days, compared to a standard over-the-needle catheter. The needle remains seated in the vein, and the assembly is less stable than a flexible plastic catheter, increasing the risk of mechanical phlebitis or accidental dislodgement and infiltration.