Venous access Cannulas OSCE

💉 Venous access is one of the most common and high-yield OSCE skills. Be systematic, maintain asepsis, and communicate clearly with the patient.

📖 Introduction

• IV access is essential in emergencies. Seek senior guidance if multiple failed attempts, or if escalation to palliative care may be more appropriate.
• 🔑 In hypovolaemic patients: avoid wasting time with small veins; use two 18G (green) cannulas to initiate fluid resuscitation.
• ⚠️ Femoral vein access (most medial in femoral triangle) offers robust access but has high infection risk → daily inspection required.
• 💡 Flow rate ∝ (cannula radius⁴ / length). → Larger, shorter cannulas = faster flow (critical in trauma or shock).
• 🖥️ Ultrasound guidance: useful in difficult-access patients.

📌 Central Lines

• Useful for irritant drugs (e.g. chemotherapy, vasopressors) or CVP monitoring.
• 🚫 Not suitable for rapid fluid resuscitation (slower flow rates than large-bore peripheral lines).
• Preferred sites: Internal jugular (compressible), Subclavian (clean but non-compressible), Femoral (easiest, but dirtiest).
• Ultrasound guidance significantly reduces complications.

📝 Procedure Introduction (OSCE style)

• ✅ Wash hands, introduce yourself, check ID, gain verbal consent.
• Check for allergies (esp. chlorhexidine/latex) & AV fistulas.
• If patient lacks capacity → act in best interests in emergency.
• Ensure name badge visible, chaperone if appropriate.

🛠️ Equipment

• Sterile gloves, apron, tourniquet, alcohol wipes
• IV cannula (choose gauge according to purpose)
• 10 ml saline flush, dressing (Tegaderm), sharps bin

🎨 Choosing the Cannula

🩺 Technique

• Apply tourniquet, palpate for suitable vein (forearm > hand > snuffbox).
• Clean skin, warn patient: "sharp scratch".
• Insert at 15–30° angle until flashback seen → advance plastic cannula off needle.
• Release tourniquet, remove needle safely, secure with dressing.
• Flush with saline to check patency → look for swelling/leakage.

📌 General Advice

• Prefer upper limbs over lower limbs.
• Work distal → proximal.
• Avoid dominant arm & limbs with dialysis fistulas.
• Replace lower limb cannulas ASAP.

⚠️ Complications

• ❌ Failed attempt (max 2–3 tries → call senior).
• 💢 Haematoma (remove tourniquet before needle withdrawal).
• 🩸 Arterial puncture (apply firm pressure, don’t reuse site).
• 🔥 Phlebitis/extravasation (esp. with irritant drugs).
• 🦠 Local infection/cellulitis, rare septicaemia.
• 🫁 Air embolism if line not flushed/secured properly.

💡 Top OSCE Tips

• Smile, reassure, explain each step clearly.
• Verbally confirm vein chosen, and check sharps bin location.
• Always flush and check patency before leaving.
• State escalation plan: "If unsuccessful after 2 attempts, I’d ask a senior/anaesthetist for assistance."