Vascular Access Techniques

Vascular Access Techniques: Prep & Prudence - Ground Zero

• Indications: Diagnostic (angiography), Therapeutic (embolization, stenting).
• Contraindications:
  • Absolute: Active infection at site, severe uncorrectable coagulopathy.
  • Relative: Moderate coagulopathy, patient refusal.
• Pre-procedural Workup:
  • History: Allergies, renal function, anticoagulants/antiplatelets.
  • Exam: Pulses, Allen's test (radial).
  • Labs: CBC, PT/INR (< 1.5-1.8), aPTT, Creatinine, Platelets (> 50,000/μL).
• Informed Consent: 📌 PRBA (Procedure, Risks, Benefits, Alternatives).

⭐ Allen's test is crucial before radial artery cannulation to ensure ulnar artery collateral circulation.

Vascular Access Techniques: Site Seeing - Entry Points

Arterial Access:

• Common Femoral Artery (CFA): Most common. Landmark: Inguinal ligament, femoral pulse. 📌 NAVEL (Lateral to Medial: Nerve, Artery, Vein, Empty space, Lymphatics).
  • Pros: Large vessel, easy access.
  • Cons: Retroperitoneal bleed risk, infection.
• Radial Artery (RA): ↑Patient comfort, ↓complications. Landmark: Styloid process of radius, radial pulse.
  • Pros: ↓Bleeding, early ambulation.
  • Cons: Smaller vessel, spasm risk.
• Brachial Artery (BA): Landmark: Medial to biceps tendon, brachial pulse.
  • Pros: Alternative if CFA/RA unsuitable.
  • Cons: ↑Nerve injury risk (median nerve).

Venous Access:

• Internal Jugular Vein (IJV): Preferred for central lines. Landmark: Triangle b/w sternal & clavicular heads of Sternocleidomastoid (SCM) muscle, carotid pulse (medial).
  • Pros: ↓DVT/pneumothorax vs subclavian.
  • Cons: Carotid puncture risk.
• Femoral Vein (FV): Medial to CFA. Landmark: Inguinal ligament, femoral pulse.
  • Pros: Easy access in emergencies.
  • Cons: ↑DVT risk, infection.
• Subclavian Vein (SCV): Landmark: Junction of medial 1/3 & lateral 2/3 of clavicle.
  • Pros: Patient comfort.
  • Cons: ↑Pneumothorax/hemothorax risk.
• Peripheral Arm Veins: (Basilic, Cephalic) For PICCs.

⭐ The Seldinger technique is the cornerstone of percutaneous vascular access, involving needle puncture, guidewire insertion, sheath placement over wire, and finally catheter introduction through sheath.

Vascular Access Techniques: Needle Ninjutsu - Technique Toolkit

• Seldinger Technique: Core method for vascular access.

• Modified Seldinger (Micropuncture):
  • Initial access with smaller 21G needle & 0.018" wire.
  • System then upsized if needed.
  • Benefits: Reduced vessel trauma, safer for challenging or small vessels.
• Ultrasound Guidance: Real-time needle and vessel visualization.
  • Views: Transverse (short-axis/out-of-plane) vs. Longitudinal (long-axis/in-plane).
  • Advantages: ↑ first-pass success, ↓ attempts, ↓ mechanical complications (e.g., hematoma, pneumothorax).
• Fluoroscopic Guidance: X-ray imaging confirms final wire/catheter position, often using bony landmarks.
• Aseptic Technique: Critical. Includes sterile field, skin prep (chlorhexidine preferred), sterile attire, draping.

⭐ The most common site for iatrogenic arterial injury during central line placement is the carotid artery when attempting internal jugular vein access on the same side.

Vascular Access Techniques: Gizmos & Gadgets - The IR Arsenal

• Needles:
  • Types: Bevelled (sharp for initial puncture), trocar-tipped (blunt dissection).
  • Sizes: 18G (standard Seldinger), 21G (micropuncture).
• Guidewires:
  • Diameters: 0.018" (micropuncture), 0.035" (standard workhorse).
  • Tips: J-tip (atraumatic navigation), angled, straight. Stiffness: floppy to stiff.
  • Coatings: Hydrophilic (↓friction), heparin (↓thrombogenicity).
• Catheters: $Fr = \text{Outer Diameter (mm)} \times 3$.
  • Types: Diagnostic (e.g., pigtail, vertebral) vs. Guiding (support).
  • Material: Polyurethane, nylon, polyethylene.
• Sheaths: Introducer with hemostatic valve & side port (flushing/infusion).

⭐ The 0.035" guidewire is the most versatile and commonly used size for a wide range of general angiography and interventions. 📌 Nice Green Cars Shine (Needles, Guidewires, Catheters, Sheaths). oka

Vascular Access Techniques: Code Red - Oops & Outcomes

• Access Site Complications:

  Complication	Key Sign(s)	Mgmt Hint
  Hematoma	Swelling, pain (most common)	Compression
  Pseudoaneurysm	Pulsatile mass, to-and-fro Doppler	US-Thrombin Inj.
  AV Fistula	Thrill/bruit, continuous Doppler	Repair
  Dissection	Intimal flap, ↓flow	Stent/Surgery
  Thrombosis	↓flow, ischemia	Anticoagulation

• Systemic/Other: Contrast reaction, air embolism, infection, nerve injury (brachial/femoral).
• ⚠️ Retroperitoneal hemorrhage: High femoral access (above inguinal lig.).
• 📌 PAIN: Pseudoaneurysm, AV fistula, Infection, Nerve injury.
• VCDs (Vascular Closure Devices): Active/Passive. Risks: failure, infection, stenosis.

⭐ Femoral puncture above the inguinal ligament (i.e., above inferior epigastric artery origin) significantly ↑ risk of retroperitoneal hemorrhage.

High‑Yield Points - ⚡ Biggest Takeaways

• Seldinger technique is fundamental for percutaneous vascular access.
• Common femoral artery: most common arterial access; Allen's test for radial artery patency.
• Ultrasound guidance is standard for central venous access; improves safety for arterial access.
• Micropuncture kits (e.g., 21G needle) reduce access site complications.
• Key complications: hematoma, pseudoaneurysm, AV fistula, infection, retroperitoneal bleed.
• Catheter sizes in French (Fr) (1 Fr = 0.33 mm); guidewires in inches.