Peripheral IV Cannula 

Basic Structure

  • Needle (introducer stylet) 
  • Catheter (plastic cannula)
  • Hub 
  • Injection port 
  • Flashback chamber 
  • Wings 

 Cannula Sizes & Color Coding 

Color

Gauge (G)

Flow Rate (mL/min)

Use

Orange

14G

~240

Trauma, massive transfusion

Grey

16G

~180

Major surgery, shock

Green

18G

~90

Blood transfusion, ICU

Pink

20G

~60

Most ICU patients

Blue

22G

~36

Elderly, fragile veins

Yellow

24G

~20

Pediatrics

(Poiseuille’s law): Flow ∝ radius⁴ → large bore > short length for rapid infusion


Site Selection

Preferred Sites

  • Dorsal hand veins
  • Cephalic vein
  • Basilic vein
  • Forearm veins

Emergency

  • Antecubital fossa (rapid access, high flow)

Avoid

  • Infected area
  • AV fistula limb
  • Post-mastectomy side
  • Lower limb (↑ thrombosis risk in adults)

Indications in ICU

  • Fluid resuscitation
  • Drug administration (IV antibiotics, vasopressors via peripheral route temporarily)
  • Blood transfusion
  • Electrolyte correction
  • Emergency access

Contraindications

Absolute

  • Local infection/cellulitis
  • Thrombosed vein

Relative

  • Coagulopathy
  • Burns
  • Edematous limb
  • Previous multiple attempts

7. Insertion Technique 

Preparation

  • Hand hygiene
  • Gloves
  • Equipment ready
  • Tourniquet applied

Steps

  1. Identify vein (visual + palpation)
  2. Clean with chlorhexidine (30 sec, allow to dry)
  3. Stabilize vein
  4. Insert cannula (15–30° angle)
  5. Observe flashback
  6. Advance slightly → thread catheter
  7. Withdraw needle
  8. Release tourniquet
  9. Connect IV line + flush
  10. Secure with sterile dressing

9. Complications 

Immediate

  • Failed attempt
  • Hematoma
  • Arterial puncture

Early

  • Phlebitis (pain, erythema, cord-like vein)
  • Infiltration/extravasation
  • Thrombophlebitis

Late

  • Infection (local → bloodstream infection)
  • Catheter-related sepsis

 Extravasation danger drugs

  • Vasopressors (noradrenaline)
  • Chemotherapy
  • Hyperosmolar solutions

10. Peripheral Vasopressor Use 

  • Allowed temporarily in emergencies
  • Use proximal large vein (forearm, not hand)
  • Use 20G or larger
  • Frequent monitoring (q5–15 min initially)

Extravasation Management

  • Stop infusion
  • Aspirate drug
  • Inject phentolamine locally
  • Elevate limb

11. Maintenance & Care

Bundle Approach

  • Daily inspection
  • Aseptic handling
  • Closed system

Replacement

  • CDC/INS guidelines:
    • Replace only when clinically indicated (not routine 72–96 hr in ICU)

Dressing

  • Transparent semipermeable dressing
  • Change if soiled/loose

12. Removal Indications

  • Signs of infection
  • Dysfunction
  • No longer required

13. Difficult IV Access (DIVA) Strategy

Difficult IV Access (DIVA) = inability to secure peripheral venous access after ≥2 attempts or anticipated difficulty due to poor vein quality.

STEP 1: Optimize Basic Technique

  • Proper lighting
  • Warm limb (vasodilation)
  • Dependent positioning
  • Use tourniquet or BP cuff (inflate to ~60–80 mmHg)
  • Vein tapping

STEP-2

  • Ultrasound-guided cannulation(Target deep veins (basilic, brachial),Long catheter-(45–60 mm) reduces failure in deep veins
  • Vein visualization devices(Near-infrared vein finder)
  • Warm compress(vasodilation)
  • Most common complication = phlebitis
  • Best emergency site = antecubital fossa