An intravenous (IV) indwelling needle—also known as an IV cannula or catheter—is a widely used vascular access tool in clinical practice. It primarily consists of a flexible catheter (cannula), a stainless steel introducer needle (stylet), and a needle hub.
I. Applications of Indwelling Needles
1. Primary Clinical Uses:
• Intravenous Infusion and Transfusion: Suitable for patients requiring intermittent, continuous, or long-term infusion therapy; it helps avoid mechanical damage to blood vessels caused by repeated punctures.
• Emergency Care and Resuscitation: Facilitates the rapid establishment of a stable venous access route for the administration of medications to critically ill patients.
• Specialized Medication Administration: Used for the delivery of antibiotics, nutritional support (such as Total Parenteral Nutrition, or TPN), or chemotherapy agents.
• Blood Specimen Collection: Certain models allow for blood sampling while simultaneously maintaining peripheral venous access for infusions.
II. Classification of Indwelling Needles
Based on their structure, function, and safety features, they are categorized as follows:
1. By Open vs. Closed System:
• Open-system Indwelling Needles: Feature an open hub design; blood leakage is common when the introducer needle is withdrawn. These are now rarely used in clinical practice.
• Closed-system Indwelling Needles: Equipped with an integrated extension tube and a closed connector (such as a positive-pressure connector). This isolates the vascular system from the external environment, preventing blood leakage and significantly reducing the risk of bloodborne infections among healthcare personnel.
2. By Needle-Stick Injury Prevention Features:
• Standard Type: Lacks an automatic protective mechanism after the introducer needle is withdrawn.
• Safety Type (Needle-stick Prevention): Features a safety mechanism that automatically covers the needle tip upon withdrawal, protecting healthcare workers from accidental needle-stick injuries.
3. By Connector and Design Configuration:
• Y-type (with extension tube): Includes a lateral extension tube, offering greater stability; ideal for patients who are more mobile or require long-term infusion therapy.
• Straight-type (pen-style): Features a compact, direct design; typically used for short-term access or specific clinical procedures. 4. Classification by size (gauge):
• Common sizes include 22G (blue; typically used for adults) and 24G (yellow; often used for infants, young children, or patients with very small/fine veins).
III. Precautions for Use and Care
1. Puncture and Vein Selection: • Do not leave the tourniquet on for too long (keep it between 40 and 120 seconds).
• Prioritize veins in the upper extremities that are large, straight, and abundant, with good blood flow. Avoid areas near joints, venous valves, or the underside of the limb. For infants and young children, avoid the inner wrist area and the thumb or index finger.
2. Aseptic Technique and Operational Standards:
• Strictly adhere to aseptic operating procedures. Before each infusion, aspirate to check for blood return, then flush the catheter with sterile normal saline. Ensure there is no resistance or leakage before connecting the infusion line.
3. Dwell Time and Replacement:
• Peripheral intravenous catheters are generally recommended to remain in place for 3–4 days (or as specified by clinical guidelines and the patient's specific condition). If local redness, swelling, pain, induration, or catheter occlusion occurs, the catheter must be removed immediately, and a new puncture site should be selected on a different limb.
4. Daily Activities and Care:
• The limb with the catheter may be moved moderately; however, avoid strenuous exercise, excessive exertion, or letting the limb hang down while carrying heavy objects, as this may cause blood to flow back into the catheter and lead to occlusion.
• Keep the puncture site clean and dry. When washing your face or bathing, cover the area securely with plastic wrap or a similar waterproof material to prevent moisture exposure and infection.
• While sleeping, avoid prolonged pressure on the limb with the catheter. When changing clothes, put the garment on the affected limb first and remove it from the unaffected limb last to prevent the catheter from being snagged or pulled out.
