Michael Menna, DO, is a board-certified active attending emergency physician at White Plains Hospital in White Plains, New York.
The butterfly needle is a device used to draw blood from a vein or provide intravenous (IV) treatment to a vein. The butterfly needle is also called a winged infusion set or a scalp venous device. It consists of a very thin hypodermic needle, two flexible “wings”, a flexible transparent tube and a connector. The connector can be connected to a vacuum tube or collection bag to draw blood, or to an infusion pump or intravenous infusion bag tubing to deliver liquids or drugs. The medication can also be delivered directly to the connector via a syringe.
Butterfly needles have certain advantages over straight needles. For example, they allow more precise placement, especially in veins that are difficult to access. However, they are not the best choice in every situation.
At first glance, a butterfly needle is similar to a Huber needle, and it also has wings. However, Huber needles are bent at a 90 degree angle so that they can be safely placed in the implanted chemotherapy port.
Phlebotomy doctors often use butterfly needles to obtain blood samples for complete blood count (CBC), cholesterol testing, diabetes monitoring, STD screening, and other blood-based tests. These needles are also commonly used in blood banks for people who want to donate blood.
If you are dehydrated and cannot drink or drink enough water to make up for fluid loss, butterfly needles can also be used to deliver intravenous fluids. They can also be used to deliver drugs (such as painkillers) directly into a vein or gradually inject IV therapies (such as chemotherapy or antibiotics) intravenously.
Although butterfly needles can stay in the vein for 5 to 7 days if properly secured, they are more commonly used for short-term infusions.
Regular or continuous infusions are usually accessed through a larger vein through a central line or peripherally inserted central catheter (PICC) line.
Although all butterfly needles are similar in design, they are still different. Butterfly needles are measured in units of specifications, usually ranging in size from 18 to 27. The higher the specification, the smaller the needle.
For example, the 27-gauge needle is the commonly used size for insulin injections. If the injectable fluid is thicker or blood is being collected for blood transfusion, use a smaller gauge needle. Most butterfly needles do not exceed three-quarters of an inch (19 mm).
The IV device or collection container is connected to the tubing connected to the needle, not to the needle. This is helpful because if you are yanked or dropped, the chance of injury is reduced.
The size of the pipe ranges from 8 inches to 15 inches (20 to 35 cm). The shorter tube is used to draw blood. Longer ones are used in IV applications and may have roller valves to adjust flow. The tubes can also be colored so that the nurse can distinguish which line is used when multiple lines are used.
Some butterfly pin connectors have a built-in “male” port that can be inserted into a vacuum tube. Other connectors have “female” ports into which syringes or tubing can be inserted.
During venipuncture (the needle is inserted into the vein), the phlebotomist or nurse will clamp the butterfly needle with the wings between the thumb and index finger. Because the hypodermic needle is shorter and the grasping distance is shorter, the placement of the butterfly needle is more accurate than the straight needle, and the straight needle will often roll or swing in the finger.
Insert a short, thin needle into the vein at a small angle. After insertion, venous pressure will force a small amount of blood into the transparent tube, confirming that the needle has been placed correctly. Once the needle is in place, the wings can also be used to stabilize the needle and prevent it from rolling or moving.
Once used (to draw blood or deliver medication), the entire device will be discarded in the sharps disposal container. Then wrap the puncture wound with a bandage.
Due to their small size (much smaller than intravenous catheters) and shallow angle design, butterfly needles can enter superficial veins near the skin surface. This not only makes them less painful to use, but also allows them to enter small or narrow veins, such as infants or the elderly.
Butterfly needles are very suitable for people with small veins or cramping (rolling), and can even be inserted into the fine veins of the hands, feet, heels or scalp.
Butterfly needles are very suitable for those who are hesitant to needles, because they are less threatening.
Once the needles are removed, they are also unlikely to cause heavy bleeding, nerve damage, or vein collapse.
Newer models have a sliding lock sheath that automatically slides over the needle when it is withdrawn from the vein, preventing needle stick injuries and reuse of used needles.
If you are told that your veins are small and have had difficulty drawing blood in the past, you may consider requesting a butterfly needle.
Due to the small size of the needle, the blood collection speed is often slow. If a person is squeamish or in an emergency situation that requires fast blood, this may cause problems in the blood bank. In this case, the choice of needle size is the key.
Even with a routine blood draw, if a large amount of blood is required, the wrong needle size can cause blockage and require a second blood draw.
Since the needle used for infusion is left in the arm, not the catheter or PICC wire, the butterfly needle can damage the vein if the device is pulled suddenly. Even if a needle of the correct size is used, if it is not placed correctly, the needle can become blocked during treatment.
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Ohnishi H, Watanabe M, Watanabe T. Butterfly needle reduces the incidence of nerve injury during phlebotomy. Arch Pathol Lab Med. 2012;136(4):352. doi:10.5858/arpa.2011-0431-LE
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Volovitz, A.; Beure, P.; Essex, D., etc. Compared with intravenous catheters, the use of butterfly needles to draw blood is independently associated with a significant reduction in hemolysis. Annual Meeting of the Academy of Academic Emergency Medicine; Atlanta, Georgia, USA; May 2013. DOI: 10.1111/acem.12245.
Post time: Nov-10-2021
