Injection Routes
Injection routes refer to the various ways medications are administered using a syringe and needle. The main routes include:
1. Intramuscular (IM) Injection
- Definition: Administration of medication directly into the muscle.
- Common Sites: Deltoid, Vastus lateralis, Gluteus maximus.
- Angle of Insertion: 90 degrees.
- Example: Vaccines (e.g., Hepatitis B, Influenza), Painkillers (Diclofenac).
- Advantages: Rapid absorption, prolonged effect.
- Disadvantages: Painful, risk of nerve injury.
2. Intravenous (IV) Injection
- Definition: Injection directly into the bloodstream via a vein.
- Common Sites: Cephalic vein, Basilic vein, Median cubital vein.
- Angle of Insertion: 25 degrees.
- Example: Antibiotics (Ceftriaxone), Chemotherapy drugs.
- Advantages: Immediate effect, accurate dosage.
- Disadvantages: Risk of phlebitis, infection.
3. Subcutaneous (SC) Injection
- Definition: Injection into the subcutaneous tissue (fat layer beneath the skin).
- Common Sites: Abdomen, Upper arm, Thigh.
- Angle of Insertion: 45 degrees.
- Example: Insulin, Heparin.
- Advantages: Slow and steady absorption.
- Disadvantages: Limited volume of drug administration.
4. Intradermal (ID) Injection
- Route: Into the dermis (just below the outer layer of the skin)
- Purpose: Localized effect or diagnostic testing
- Common Uses: Tuberculosis (Mantoux test), allergy testing
- Common Sites: Forearm, upper back
- Example: Tuberculin test, Xylocaine Sensitivity Test
5. Intra-articular Injection
- Route: Into a joint space
- Purpose: Direct treatment for joint-related conditions
- Common Uses: Arthritis, pain relief
- Example: Corticosteroid injection in the knee joint
6. Intrathecal Injection
- Route: Into the cerebrospinal fluid (CSF) via the spinal canal
- Purpose: Direct action on the central nervous system (CNS)
- Common Uses: Spinal anesthesia, chemotherapy, pain management
- Example: Epidural anesthesia during childbirth
7. Intraosseous (IO) Injection
- Route: Into the bone marrow
- Purpose: Emergency drug administration when IV access is not possible
- Common Uses: Pediatric emergencies, trauma patients
- Example: Fluids and medications in shock patients
8. Intraperitoneal (IP) Injection
- Route: Into the peritoneal cavity (abdomen)
- Purpose: Chemotherapy, dialysis, experimental drug administration
- Common Uses: Peritoneal dialysis for kidney failure
- Example: Chemotherapeutic drugs in cancer treatment
9. Intrapleural Injection
- Route: Into the pleural cavity (around the lungs)
- Purpose: Direct action on the lungs
- Common Uses: Pleural effusion, cancer treatment
- Example: Chemotherapy for lung cancer
10. Intracardiac (IC) Injection
- Route: Directly into the heart
- Purpose: Emergency resuscitation
- Common Uses: Cardiac arrest situations (rarely used now)
- Example: Epinephrine injection in cardiac emergencies
11. Intravitreal (IVT) Injection
- Route: Directly into the vitreous humor of the eye
- Purpose: Targeted drug delivery for eye diseases
Common Uses:
- Age-related macular degeneration (AMD)
- Diabetic retinopathy
- Retinal vein occlusion
- Eye infections (endophthalmitis)
Example Drugs:
- Anti-VEGF (e.g., Bevacizumab, Ranibizumab, Aflibercept)
- Corticosteroids (e.g., Dexamethasone implant)
- Antibiotics for intraocular infections
This type of injection must be done with strict aseptic techniques to avoid complications like endophthalmitis (serious eye infection).
Intravenous Infusion (IV Infusion)
- Definition: Continuous administration of fluids/medications into a vein over a period.
- Common Fluids Used: Normal saline (0.9% NaCl), Ringer's lactate, Dextrose.
- Example: Hydration therapy, Blood transfusion.
- Advantages: Controlled delivery, better patient management.
- Disadvantages: Requires venous access, infection risk.
Infusion Pump
- Definition: A medical device that delivers fluids, medications, or nutrients at a controlled rate.
- Types:
- Volumetric pumps (for large volumes of fluids)
- Syringe pumps (for precise, small volume administration)
- Example: Morphine infusion for pain management.
- Advantages: Accurate dosage, reduced medication errors.
- Disadvantages: Expensive, requires technical expertise.
Syringe Parts
A syringe consists of three main parts:
- Barrel: Holds the medication.
- Plunger: Pushes medication into the needle.
- Needle hub: Connects the needle to the syringe.
4. Needle Gauge and Uses
| Gauge Number | Outer Diameter (mm) | Common Use |
|---|---|---|
| 16G - 18G | 1.2 - 1.6 mm | Blood donation, IV fluids |
| 20G - 22G | 0.9 - 1.1 mm | IM injections, IV therapy |
| 23G - 25G | 0.6 - 0.7 mm | SC injections, Pediatric injections |
| 26G - 30G | 0.3 - 0.5 mm | Insulin injections, Intradermal tests |
Needle Color Code & Gauge Size
Needles are categorized by gauge (G) size, which determines their diameter and use. The color of the hub helps quickly identify the gauge.
- Lower gauge number = Larger needle diameter (thicker fluids, rapid injections).
- Higher gauge number = Smaller needle diameter (delicate veins, slow injections).
Needle Color Code Chart
| Color | Gauge (G) | Outer Diameter (mm) | Common Uses |
|---|---|---|---|
| Pink | 18G | 1.2 mm | IV infusions, blood donation |
| Green | 21G | 0.8 mm | Routine blood collection, IV injections |
| Black | 22G | 0.7 mm | Blood draws, small veins |
| Blue | 23G | 0.6 mm | Pediatric injections, fragile veins |
| Yellow | 24G | 0.55 mm | Neonates, infants, delicate veins |
| Violet | 26G | 0.45 mm | Insulin injections, intradermal tests |
How to Identify Needle Gauge by Color?
- Look at the needle hub (plastic base) → It is color-coded according to gauge size.
- Larger needles (lower gauge, e.g., 18G, 21G) → Used for blood draws, IV fluids.
- Smaller needles (higher gauge, e.g., 24G, 26G) → Used for pediatrics, insulin, delicate veins.
Conclusion
Understanding different injection routes, infusion methods, and syringe/needle types is crucial for safe and effective drug administration. Proper knowledge ensures correct drug delivery, minimizes patient discomfort, and prevents complications.
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Nursing-procedure