Syringes and Needles
Syringes and needles serve in four essential roles--as 1) injection devices, 2) fluid or biopsy collection, 3) irrigation, or 4) suction. In the first role of injection devices, they administer medications into the body. Common injections include insulin, vaccines, anxiolytics, analgesics, anesthetics, antibiotics, muscle relaxants, hormones, vitamins, anticholinergics, antimuscarinics, & others.1 For fluid or biopsy collection, they extract blood, cerebrospinal, amniotic, synovial, peritoneal, pericardial, and pleural fluids as well as tissue samples.2 For irrigations common fluids used include aminoglycosides, antibiotics, corticosteroids, saline, & vasoconstrictor epinephrine solutions.3 Lastly for suctioning, these devices aspirate airway passages to remove mucus and vomit. Some designs target other obstructions like ear wax or venom.
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Syringes and Needles Applications
- invasive procedure
- invasive procedure
- blood & fluid draws
- biopsy sampling
- minimally invasive
- cleansing & flushing
- minimally invasive
- ear wax
The design of these instruments centers on both the user and the patient. The functions of injection, sampling, and irrigation are slightly dissimilar, requiring minor modifications to these devices to accomplish the task best. These modifications become selection criteria when choosing the best syringe & needle for your needs. The selection criteria fall into four basic categories. These categories and the factors display below.
Selection Criteria for the Best Syringes and Needles
- volume visibility
- plunger pressure
- fluid draw
- inject medications
- reduce pain
- reduce bruising
- comfort & ease
Caregivers or administrators must prepare the medication, load the correct dosage into the syringe, insert the needle into the correct tissue at the right angle, administer the medication with the right amount of pressure on the plunger, remove the needle when administration is complete, dispose of sharp waste, and do this all without accidentally sticking themselves. Selecting the right size syringe with the correct size needle for the type of medication and administering it to the best delivery site can be a daunting task. The process of loading the syringe to the correct dosage, and then administering the medication can become tedious. Easy to read dosage markers on the side of the syringe barrel helps with preparation. Also, transparent syringes allow administrators to see the medication against the measurement markers. Easier visibility makes it simpler to get the correct dosage. A smaller syringe requires more pressure to push the plunger. Larger sizes require less pressure. Safety Needles help protect the user from accidental stick injuries. Healthcare workers that conduct numerous injections daily with contagious patients are wise to use safety devices to protect themselves. Note that in many home applications, the administrator is also the patient.
As mentioned above, syringes and medical needles perform four basic services of drawing fluid or tissue samples, performing medication injections, wound irrigation, and intravenous applications. The tool you select should match the task you are performing. Select phlebotomy supplies for blood draws, biopsy kits for sampling, syringes and needles for medication delivery, irrigation supplies for cleansing & flushing, and IV Supplies for intravenous administration.
Why Doctors Favor Injections Over Pills
Many medications need to get into the general circulation of fluids in your body — the bloodstream, in particular — in order to flow to their sites of action. Ideally, 100% of a drug gets to its destination. In practice, most medications need to pass through multiple barriers in your body (biologic membranes) and undergo a complex series of biochemical reactions along the way, some of which "use up" a portion of the active ingredient.
When a medication is given intravenously, it enters the circulation directly and is considered 100% available to your body. When taken by mouth, it has to go through part of your digestive system first. Only some of the drug makes it to the site of action; the rest is effectively processed as waste. This concept is called bioavailability: the portion of the drug that actually makes it into your circulation.4
The syringe will need to be large enough to accommodate the volume of medication prescribed. They are available in different sizes to meet volume requirements. They are usually measured in milliliters (mL) and centimeters (cc). Viscosity is another important consideration. The thicker the medication, the larger the needle diameter needs to be to allow the fluid to pass through. The smaller the gauge number, the larger the diameter of the needle. On the other hand, the larger the gauge number, the smaller the diameter of the needle. Medications with a high viscosity require lower gauge numbers to accommodate the flow of the thicker fluid.
Patients can easily stress over injections. For many, the level of patient stress directly relates to the pain associated with the injection. But pain is not the only concern. Needle punctures can cause bruising. Longer and wider diameter needles cause more pain and bruising. Short length delivery devices and those with smaller diameters cause less pain and bruising. Sometimes the administrator and the patient are the same person. In a case like this, the more accommodations the syringe and needle make for self-administration, the better.
Selecting the Best Needle
Anatomy of a Needle
Types of Medical Needles
There are six major types of syringe needles for sale. Four have a sharp bevel shape stainless steel tip for piercing the skin and tissue. The fifth type is a blunt needle used for cannula. Blunt tips come in plastic or metal. The last type is a safety tip that shields the needle from accidental sticks.
- Regular bevel is the most common tip type. Subcutaneous and intramuscular injections are the typical use of this bevel type.
- Short bevel tips offer specialty applications such as arterial blood gas sampling or nerve blocks. Its design supports minimal injection depth and rapid withdrawal and fluid dispersion.
- Intradermal bevel provides for shallow and low angle insertions just below the epidermis. This needle tip offers a good method for testing skin for allergies.
- 5-bevel has a flatter, thinner surface found to be less painful for patients.
- Blunt tips or dispensing needles prepare and dispense medications to patients usually through an IV device instead of being injected directly into the patient. These tips are safer for caregiver use since they do not have a sharp tip.
- Safety tips protect the user from accidental stick injuries. They are available in retracting, shielding, and sliding sleeves.
Many manufactures now make safety tips. The chart above displays several top-selling safety tips, including the Medtronic Magellan, BD SafetyGlide, Medtronic Monoject, BD Safety-Loc, Sol-Millennium SOL-Guard, EasyTouch FlipLock
Needle Selection Criteria
A needle provides the primary function of administering injectable medications. Injectables are a growing medical application. US hospital drug spending for injectables reached $25.8 billion in 2016. "In acute-patient-care settings, injectable drugs are used ubiquitously. Injectables offer several advantages over other administration routes, including precise and adjustable dosing, predictable bioavailability, and fast onset of action."5 To select the best needle for your needs first starts with the type of injection. There are three types of injections, along with sites on the body, to perform those injections. After determining the type of injection, next is determining the needle gauge and then the needle length.
Needle Injection Types
There are three typical injection sites--intradermal, subcutaneous, and intramuscular. The deeper the injection site, the longer the length of the needle and the more direct or perpendicular the needle route to the delivery tissue. However, the shorter the needle length, the less pain or bruising experienced by patients receiving injections. "Procedural pain in general, and intramuscular (IM) injection pain in particular, is one of the most distressing and painful health care experiences for children."6
Intradermal infusions take place in the dermis layer of tissue that lies just beneath the epidermis layer of skin. The dermis is only a few millimeters thick on most parts of the body. Most of these injections take place with a needle length of 1/2 to 5/8 inch and at an angle of 10- to 15-degrees to the skin. Recommended sites for intradermal injections to adults and infants include the anterior aspect of the forearm, upper chest, upper back, or the back of the upper arm. Many consider this method the most difficult of the three injection types.
Subcutaneous infusions occur in the tissue layer between the dermis and muscle. A short needle of 1/2 to 5/8 inch performs this action. The needle length used for subcutaneous injections overlaps the needle length used for intradermal injections. Medication volumes for this injection type are usually less than 1 m, but up to 2 mL is safe. Injections of this type employ an angle of 45- to 90-degrees to the skin surface. Epinephrine, morphine, hydromorphone, metoclopramide, dexamethasone, allergy medications, and vaccines are common drugs injected subcutaneously.
These injections reach down through the dermis and subcutaneous tissue into the muscle. Longer needles reach muscle tissue at this depth of 7/8 to 1-1/2 inches. Injections take place at a 90-degree angle to the skin. Best injection sites include the deltoid muscle, the vastus lateralis, the ventrogluteal, and the dorsogluteal.
Needle Gauge Selection Criteria
There are several factors to consider when selecting the best needle gauge. First is the type of injection. For intradermal injections (displayed in purple on the continuum above), a gauge of 26 to 28 is usually sufficient. For subcutaneous injections (displayed in orange), 19 to 27 gauge works well. Intramuscular injections (displayed in blue) call for gauge sizes of 26 to 30. Notice that there is an overlap of all three injection types for gauges 27 and 26. These two gauges make a good all-round choice for the three injection types.
Another factor to consider in choosing the needle gauge is the viscosity of the medication. The thicker the viscosity of the fluid, the lower should be the gauge size to allow the medication to flow freely.
Another factor is the fact that the lower the gauge number, the stronger the needle, resulting in less risk of bending or breaking the needle. For injections of tough skin areas, a lower gauge number may be necessary to ensure the needle will not be compromised.
Pain is the last factor to consider. The higher the gauge number, the less pain or bruising experienced by the patient. Lower gauge numbers are thicker, which cause more pain and more bruising; and therefore, more patient trauma.
Patient bruising is a similar factor as pain. The thicker the puncture device, the greater the risk of bruising the patient. Also, the longer the needle, the greater the risk of bruising.
Needle Length Selection Criteria
As shown in the continuum above, intradermal injections (displayed in purple) take place with a needle that is ⅜ to 5/8 inches in length. Subcutaneous injections (displayed in orange) are best with 1/2 to 5/8 inch needles. There is an overlap with a 1/2 and 5/8 inch needle for completing both intradermal and subcutaneous injections. Intramuscular injections require the longest needle length to reach down to muscle tissues at 7/8 to 1-1/2 inch needle length.
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Selecting the Best Syringes FOR SALE
Anatomy of a Syringe
A syringe tip is the end of the syringe in which the needle hub attaches. In the graphic above, a Luer Lock tip displays on the tip.
The tip of the plunger is a soft material attached to the plunger that squeezes against the walls of the barrel to contain the medication within the tip end of the barrel. It also serves as the measurement marker for medication volume. The plunger tip creates a vacuum as it moves away from the syringe tip, drawing in the medication. As the plunger moves toward the syringe tip, it forces out the medication.
The barrel of the syringe is a hollow cylinder that fills with medication (aspiration) and then expels (administration) the medication into the patient. Markings on the side of the barrel provide volume indications. In the graphic above, the numbered markings indicate centimeters (cc), while the unnumbered markings indicate millimeters (mL) in increments of 2.
The two wings, called the flange, located on the opposite end from the syringe tip, extends out from the end of the barrel. The flange provides support to the index finger and the middle finger for grasping during aspiration and administration.
The plunger rod runs from the plunger tip to the thumb press. It serves as the connection for the user to the plunger tip to first draw medication and then to force the medication out of the syringe.
The thumb press is the pressure point on the plunger where the thumb presses down to force the medication out of the barrel, through the needle, and into the patient.
Selecting a Syringe Tip
Syringe tips come in five basic configurations. Luer Lok tips are the most popular. Luer Lok tips have a screw-type connection that keeps the needle secure to the syringe. The Catheter Tip has a long, tapered tip to allow tubing and catheters to attached for irrigation or flushing. The Slip Tip is a shorter version of the Catheter Tip that allows the needle hub to slip or push-on to the syringe. The Eccentric Tip has an off-center tip that is useful for surface veins or artery injections. The last tip is a fixed tip with a needle that is not detachable.
Luer Lock Tip
Luer Lock tips utilizes a screw mount that locks and secures the needle hub to the syringe. This tip is compatible with a variety of medical needles, catheters, and other devices that employ this type of connection.
The Slip Tip employs a friction-fit connection. The tip of the syringe slides into the needle hub fitting in a push and twist motion. It is considered less secure than the Luer Lock system.
Eccentric tips are offset from the center of the syringe to allow closer proximity to the skin. The connection works similar to the slip tip. Useful for venipunctures and fluid aspiration.
The Catheter Tip is longer, tapered, and narrows to the tip. It has a slip-on and slip-off connection designed for tubing. It used for flushing catheters, gastrostomy tubes, and other devices. Just slide the tubing onto the catheter tip and slide off when done.
Permanently Attached Needle
Smaller syringe needle combinations often have the Needle Permanently Attached to the syringe. Sometimes referred to as an integral needle, it easy to use and simple to dispose. Insulin and tuberculin injections commonly use smaller combinations.
Syringe Size Selection
Syringes are available in many sizes and selected based upon the volume of administered medication. Subcutaneous and intramuscular injections often take place with smaller volume syringes. Small volume syringes exert higher pressure flows for injecting the medication. Larger syringe sizes offer lower pressure flows. For central lines, catheters, and tubing applications, 10 to 12 mL sizes are in common use. Higher volume syringes of 20 to 70 mL have irrigation applications.
A large syringe is the mainstay for irrigation. Wound irrigation for cleansing and debriding is the most often use for these devices. Syringes used for irrigation usually have a size of 50 to 70 mL. Saline solutions are the most common irrigation fluid, followed by aminoglycosides, antibiotics, corticosteroids, and vasoconstrictor epinephrine solutions. Irrigation involves two separate steps—draw and eject. The user draws the solution and then ejects it upon the area for irrigation.
Irrigation Syringe Styles
Piston devices often employ a double-flanged plunger tip that seals against the walls of the barrel. It provides a vacuum to fill the barrel with various irrigation solutions. It also offers a smooth piston action to expel solutions to cleanse and flush.
Bulb devices do not employ a plunger but instead, have a flexible blub at the end of the barrel where the thumb press would normally be. Squeezing the bulb forces air out and releasing the bulb forms a vacuum to draw in solutions. The user submerges the syringe tip in the irrigation solution to draw the solution into the barrel. The user then again squeezes the bulb to force the solution out of the barrel to irrigate. There are several types of bulb syringes in use, including ear syringes, mucus syringes, Green-Bulb syringe, Clear-View syringes, and others.
The thumb press located on the opposite end of the plunger from the plunger tip or grommet. The user or administrator presses down on the thumb press to eject the irrigation solution out of the barrel of the syringe.
A thumb ring or thumb control syringe replaces the thumb press on the syringe to provide more control by the user during the draw and eject cycles of irrigation.
Straight tips use a tapered, catheter sytle tip.
Curved tip devices use a long tip the curves 90 degrees. It is useful for areas difficult to irrigate with a straight tip.
Grommetless devices on a piston syringe do not have a plunger tip at the end of the plunger.
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Also known as aspiration syringes and suction bulbs, this type will remove obstacles in the airways like mucus and vomit. They are also tools in surgical operations and in the removal of ear wax & venom. They are available in numerous sizes—10 mL, 30 mL, 60 mL, 90 mL, and 120 mL being the most common. The larger the syringe size or bulb size, the higher the vacuum force.7
Suction Syringe Types
There are two different types of suction devices in wide use today. Similar to irrigation devices, they are bulb and piston syringes
These aspiration devices are very similar in size and shape. They include a long, tapering tip, stem, or tubing to gain access to the area requiring suction. The bulb type is the best selling. The design of these instruments is for single patient use only, but they can be washed and reused with the same patient.
Piston suction devices nearly always employ tubing as part of the device. The tubing is flexible and able to reach the areas that require suction. Many come with a measurement scale marked on the side of the barrel. These devices are less easy to use that the bulb versions, but they provide for accurate measurements.
Phlebotomy and Blood Drawing Supplies
The keys to selecting the right blood collection supplies or Phlebotomy Supplies are their simplicity of use and safety. These supplies should be easy to use and quick to accomplish their task. They should be safe to use, preventing accidental needle sticks.
Types of Phlebotomy Systems
There are three types of blood drawing supplies—closed, vacuum, and open. Closed systems offer a safer system with less risk of contamination and reduced blood waste. In-Line design protects patients for exposure to bacteria. Vacuum systems use a Vacuum Tube for the collection device and is a closed system. Additional vacuum tubes inserted one after the other can collect more blood for other tests without additional punctures to the patient. This system also protects the caregiver from blood exposure. The system comes complete with a needle, barrel and laboratory sample tubes. Tube sizes for adults and pediatrics are available. Open systems employ a hypodermic needle and syringe or a steel winged needle for blood sample collection.8
- 1 Vail, Emily and Patel, Mona. "Clinical Use of Generic Injectable Drugs in Hospitalized Patients." Pharmacy Times. 2017. (Last Accessed February 25, 2020)
- 2 "Testing irreplaceable body fluids." Streck, December, 2019 (Last Accessed February 26, 2020)
- 3 Thieman, Corey, and Fekadu Fullas. "Pharmacist Rounds: Surgical Irrigation Fluids--To Warm or Not-Although the jury is still out, the majority of published reports support the use of warm irrigation fluids to minimize the risk of hypothermia in surgical procedures." Pharmacy Times 75.8 (2009): 56. (Last Accessed February 26, 2020)
- 4 Mui, Katie, "Why Do Some Medications Come As Pills, And Others As Injections?" GoodRx. (Last Accessed February 25, 2020)
- 5 Vail, Pharmacy Times.
- 6 Yilmaz, Gamze, and Dilek Küçük Alemdar. "Using Buzzy, Shotblocker, and bubble blowing in a pediatric emergency department to reduce the pain and fear caused by intramuscular injection: A randomized controlled trial." Journal of Emergency Nursing 45.5 (2019): 502-511. (Last Accessed February 27, 2020)
- 7 Haseler, Luke J., et al. "Syringe and needle size, syringe type, vacuum generation, and needle control in aspiration procedures." Cardiovascular and interventional radiology 34.3. 2011. page 16. (Last Accessed February 27, 2020)
- 8 World Health Organization. "WHO Guidelines on Drawing Blood: Best Practices in Phlebotomy." World Health Organization. 2010 (Last Accessed February 27, 2020)
- World Health Organization. WHO guideline on the use of safety-engineered syringes for intramuscular, intradermal and subcutaneous injections in health-care settings. No. WHO/HIS/SDS/2015.5. World Health Organization, 2015. (Last Accessed March 4, 2020)
- Beyea, Suzanne C., and Leslie H. Nicoll. "Administering IM injections the right way." AJN The American Journal of Nursing 96.1 (1996): 34-35. (Last Accessed March 4, 2020)
- Schleis, Thomas G., and Alan D. Tice. "Selecting infusion devices for use in ambulatory care." American journal of health-system pharmacy 53.8 (1996): 868-877. (Last Accessed March 4, 2020)
- Hansen, Birtha, and Irina Matytsina. "Insulin administration: selecting the appropriate needle and individualizing the injection technique." Expert opinion on drug delivery 8.10 (2011): 1395-1406. (Last Accessed March 4, 2020)
- Nicoll, Leslie H., and Amy Hesby. "Intramuscular injection: an integrative research review and guideline for evidence-based practice." Applied nursing research 15.3 (2002): 149-162. (Last Accessed March 4, 2020)
- McKay, Maureen, Gerhard Compion, and Lene Lytzen. "A comparison of insulin injection needles on patients' perceptions of pain, handling, and acceptability: a randomized, open-label, crossover study in subjects with diabetes." Diabetes technology & therapeutics 11.3 (2009): 195-201. (Last Accessed March 4, 2020)
- Le, Jennifer, "Drug Administration." Skaggs Schools of Pharmacy and Pharmaceutical Sciences, University of California San Diego. Merck Manual, Consumer Version. June 2019. (Last Accessed February 25, 2020)