Central venous cannulation - anatomical landmarks techniques advantage and disadvantages of each approach complications various applications in md anaesthesia as an exam question with table viva questions
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I now have comprehensive, authoritative content from Miller's Anesthesia and Roberts & Hedges. Let me compile the full exam-oriented answer:
Central Venous Cannulation - MD Anaesthesia Exam Question
DEFINITION & OVERVIEW
Central venous cannulation (CVC) involves placement of a catheter into a large central vein (internal jugular, subclavian, or femoral) such that its tip lies at the cavo-atrial junction. It is one of the most commonly performed invasive procedures in anaesthesia and critical care.
INDICATIONS (Box 32.5 - Miller's Anesthesia, 10e)
| Category | Specific Indication |
|---|---|
| Monitoring | CVP monitoring, PAC placement, transvenous cardiac pacing |
| Drug administration | Vasoactive drugs, TPN/hyperalimentation, chemotherapy, irritant drugs |
| Resuscitation | Rapid fluid infusion (large cannulae), trauma, major surgery |
| Renal | Temporary haemodialysis, CRRT |
| Access | Poor peripheral IV access, repeated blood sampling |
| Diagnostic | Air embolus aspiration |
SELDINGER TECHNIQUE (Standard Method)
- Venepuncture with finder/introducer needle attached to syringe under gentle aspiration
- Free, non-pulsatile blood return confirms venous placement
- Guidewire (J-tipped) passed through needle into vessel
- Needle removed; wire retained
- Skin incision with scalpel
- Dilator passed over wire to dilate tract
- Catheter threaded over wire into vessel
- Wire removed; catheter flushed and secured
- Confirm tip position with CXR at cavo-atrial junction
APPROACHES - ANATOMY, LANDMARKS, TECHNIQUE
1. INTERNAL JUGULAR VEIN (IJV)
Anatomy:
- Exits the jugular foramen, runs within the carotid sheath alongside the carotid artery
- Lies lateral to the common carotid artery at the level of the thyroid cartilage
- Courses deep to the sternocleidomastoid (SCM) to join the subclavian vein behind the sternoclavicular joint
Approaches:
| Sub-approach | Landmark / Needle Entry | Direction |
|---|---|---|
| Central (most common) | Apex of triangle formed by sternal and clavicular heads of SCM + clavicle | 30-45° to skin, toward ipsilateral nipple |
| Anterior | Medial border of SCM at level of thyroid cartilage | 30-45°, avoid carotid |
| Posterior | Posterior border of SCM, above junction of middle and lower thirds | Toward suprasternal notch |
Position: Supine, Trendelenburg 15°, head turned 30-45° to contralateral side
Advantages:
- Direct path to SVC from right side
- Carotid artery puncture easily detected and compressed
- Lower pneumothorax risk vs. subclavian
- Best route for emergency transvenous pacing (right IJV - most direct to RV)
- Haematoma visible and compressible
- Preferred in coagulopathy
Disadvantages:
- Carotid artery puncture rate 5-15%
- Poor landmarks in obese, oedematous, or short-necked patients
- Higher infection risk than subclavian (respiratory secretion contamination)
- Patient discomfort; head must be turned
- Catheter malposition less common than subclavian
Catheter insertion depth (right IJV): ~15 cm to cavo-atrial junction
2. SUBCLAVIAN VEIN (SV)
Anatomy:
- Continuation of axillary vein at the lateral border of 1st rib
- Passes anterior to the anterior scalene muscle (subclavian artery is posterior to it)
- Joins IJV behind sternoclavicular joint to form brachiocephalic vein
- Separated from the pleura by only the anterior scalene muscle and subclavius muscle
Approaches:
| Sub-approach | Entry Point | Direction |
|---|---|---|
| Infraclavicular (classic) | 1 cm below clavicle, at junction of medial and middle thirds | Horizontally medial, under clavicle, toward suprasternal notch |
| Supraclavicular | 1 cm lateral to clavicular head of SCM, 1 cm posterior to clavicle | Bisects the clavicosternomastoid angle; 10-15° above horizontal toward contralateral nipple; depth 2-3 cm |
Position: Supine, slight Trendelenburg, roll between shoulder blades
Advantages:
- Lowest rate of catheter-related bloodstream infection (CLABSI) - preferred by SHEA/IDSA/AHA for ICU
- Lowest thrombosis rate (DVT ~1.9%)
- Better neck mobility for patient
- Preferred in cervical collar/trauma patients
- Acceptable during CPR (supraclavicular - avoids chest compression interference)
- Lowest CLABSI risk
Disadvantages:
- Highest pneumothorax risk (1.5% landmark technique)
- Non-compressible site - arterial injury hazardous
- Contraindicated in severe emphysema/bullous lung disease (if other options available)
- Higher catheter malposition rate
- Cannot use ultrasound easily (clavicle obstructs)
- Contraindicated in clavicle fracture/chest wall deformity
Note on sides: Right subclavian preferred - lower pleural dome, more direct SVC route, thoracic duct on left
Catheter depth: 16-17 cm (right), 18-19 cm (left)
3. FEMORAL VEIN (FV)
Anatomy:
- Continuation of popliteal vein; runs medial to femoral artery in the femoral sheath
- Located within the femoral triangle (inguinal ligament superiorly, sartorius laterally, adductor longus medially)
- Mnemonic: NAVEL - Nerve, Artery, Vein, Empty space, Lymphatics (lateral to medial)
Landmarks:
- Palpate femoral artery 2 fingerbreadths below the inguinal ligament
- Femoral vein lies 1 cm medial to the artery
- Alternatively: divide inguinal ligament (ASIS to pubic symphysis) into thirds - femoral artery at medial-middle third junction, vein 1 fingerbreadth medial
- Needle entry at 45° directed cephalad toward umbilicus
Position: Supine, slight external rotation of thigh
Advantages:
- Simplest, most accessible anatomy
- No pneumothorax risk
- No risk to major thoracic vessels
- Useful in coagulopathy (compressible)
- Emergency cardiopulmonary bypass, haemoperfusion, dialysis
- Access unaffected by resuscitation activity at head/chest
- Does not interrupt CPR
- Useful in children
Disadvantages:
- Highest DVT rate (~21.5%)
- Highest infection rate (CLABSI highest among three sites)
- Contraindicated in ambulatory patients
- Long catheter required to reach IVC (25 cm or more)
- Risk of retroperitoneal haematoma if needle too high
- Inferior vein placement can give incorrect CVP readings
- Not ideal for CVP monitoring (intra-abdominal pressure artefact)
COMPARISON TABLE - THREE APPROACHES
| Parameter | Internal Jugular | Subclavian | Femoral |
|---|---|---|---|
| Infection (CLABSI) | Intermediate | Lowest | Highest |
| DVT risk | Intermediate | Lowest (1.9%) | Highest (21.5%) |
| Pneumothorax | Low (0.5%) | Highest (1.5%) | None |
| Arterial injury | Carotid (compressible) | Subclavian (non-compressible) | Femoral (compressible) |
| Catheter malposition | Low | Highest | Low |
| Ultrasound guidance | Strongly recommended | Difficult (clavicle) | Recommended |
| Compressibility if arterial hit | Yes | No | Yes |
| CPR compatibility | Yes (away from chest) | Yes (supraclavicular) | Yes |
| Coagulopathy | Preferred | Avoid | Acceptable |
| Cervical trauma/collar | Difficult | Preferred | Alternative |
| Transvenous pacing | Right IJV (best) | Possible | Possible |
| Emergency access | Good | Good | Easiest |
| Catheter length to CVJ | ~15 cm (R IJ) | 16-17 cm (R SC) | >25 cm |
COMPLICATIONS
A. Mechanical (Immediate)
| Complication | Notes |
|---|---|
| Arterial puncture | Most common acute complication (1.9-15%); carotid or subclavian; compress if possible |
| Pneumothorax | Subclavian > IJV; CXR mandatory post-procedure |
| Haemothorax | Venous or arterial injury into pleural space |
| Haematoma | Local, usually self-limiting |
| Air embolism | Prevented by Trendelenburg position; use Valsalva during hub changes |
| Cardiac tamponade | Malpositioned catheter tip perforating SVC/RA/RV wall |
| Arrhythmias | Guidewire or catheter tip irritating RV; withdraw promptly |
| Nerve injury | Brachial plexus, stellate ganglion, phrenic nerve, recurrent laryngeal nerve |
| Hydromediastinum/Hydrothorax | Malpositioned catheter; fluid infused into mediastinum/pleura |
| Chylothorax | Left-sided approach near thoracic duct |
| Catheter/guidewire embolism | Equipment misuse; never release guidewire completely |
B. Thromboembolic (Delayed)
- Catheter-related DVT: femoral 21.5% > subclavian 1.9%
- Pulmonary embolism
- Superior vena cava syndrome
- Catheter tip thrombus → nidus for infection
C. Infectious
- CLABSI (Central Line-Associated Bloodstream Infection): most common major late complication
- CLABSI rates declined ~50% (2008-2016) but rose 91% during COVID pandemic
- Risk order: femoral > IJV > subclavian
- Causative organisms: Staphylococcus epidermidis (most common), S. aureus, Gram-negatives, Candida
- Prevention: Maximal barrier precautions, chlorhexidine skin prep, hand hygiene, daily review of necessity, antimicrobial-impregnated catheters (chlorhexidine/silver sulfadiazine or minocycline/rifampicin)
D. Misplacement
- Tip in wrong vessel (ipsilateral IJV, contralateral brachiocephalic, hepatic vein)
- Too deep → RV → arrhythmias
- Confirm with CXR: tip should be at cavo-atrial junction (SVC-RA junction, level of carina/2nd rib junction)
CONFIRMATION OF CENTRAL VENOUS PLACEMENT
- Free aspiration of dark, non-pulsatile blood
- Pressure transduction - venous waveform (low pressure, respiratory variation)
- Waveform manometry (fluid column falls on raising - venous; rises - arterial)
- Blood gas analysis (venous PO2 35-45 mmHg, SpO2 ~65-75%)
- CXR: tip at cavo-atrial junction (right tracheobronchial angle on PA film)
- Echocardiography (bubble test/agitated saline) - increasingly used in ICU
SPECIAL CONSIDERATIONS IN ANAESTHESIA
| Clinical Scenario | Preferred Route | Reason |
|---|---|---|
| Emergency transvenous pacing | Right IJV | Most direct path to RV |
| Coagulopathy | IJV or femoral | Compressible if arterial injury |
| Severe emphysema | IJV | Avoid pneumothorax of subclavian |
| Cervical trauma/collar | Subclavian or femoral | Cannot access neck |
| CPR in progress | Supraclavicular subclavian or femoral | Away from chest compressions |
| ICU long-term | Subclavian | Lowest CLABSI rate |
| Children | Femoral or IJV | Easier access, less pneumothorax risk |
| Obesity | Femoral (US-guided) | Poor neck landmarks for IJV |
| Pulmonary artery catheter | Right IJV | Straight route to PA |
| Severe orthopnoea | Supraclavicular subclavian | Can be done sitting |
ULTRASOUND GUIDANCE
- Now strongly recommended for IJV cannulation (NICE guidance, ASA guidelines)
- Should be considered for subclavian and femoral
- Reduces arterial puncture, haematoma, failed first-pass
- Static (pre-procedure mapping) vs. dynamic (real-time guidance) - dynamic preferred
- Axillary vein approach under ultrasound: first-pass 76%, overall success 96%; lower pneumothorax risk
Benefits vs. Concerns (Miller's Box 50.1):
- Benefits: Reduced arterial puncture, reduced pneumothorax, real-time vessel visualisation
- Concerns: Potential loss of landmark skills, equipment dependency, learning curve
VIVA QUESTIONS
Q1. What are the boundaries of the triangle used for IJV central approach?
A: Sternal head of SCM (medially), clavicular head of SCM (laterally), and the clavicle (base). The IJV lies at the apex of this triangle.
Q2. Why is the right side preferred for IJV cannulation?
A: The right IJV provides a straight, direct path to the SVC and right atrium. The left side has the thoracic duct at the confluence, and the left brachiocephalic vein makes a curve, increasing catheter malposition risk.
Q3. Why is subclavian vein non-compressible and what are the implications?
A: The subclavian vein passes under the clavicle - if the subclavian artery is punctured, the overlying clavicle prevents manual compression, leading to potentially life-threatening haemorrhage or haematoma. This is why subclavian cannulation is relatively contraindicated in coagulopathic patients.
Q4. How do you distinguish arterial from venous puncture during CVC insertion?
A: (1) Pulsatile vs. non-pulsatile blood flow; (2) Colour - bright red (arterial) vs. dark (venous); (3) Blood gas: PO2 >70 mmHg suggests arterial; (4) Pressure transduction: arterial waveform; (5) Column test: blood rises in IV tubing when held upright if arterial, falls if venous.
Q5. What is the significance of catheter tip position? Where should it ideally lie?
A: Tip should lie at the cavo-atrial junction (lower SVC/right atrium junction) - at or just above the pericardial reflection. If too deep (in RV): arrhythmias. If tip abuts the SVC wall at a steep angle: risk of cardiac tamponade from perforation.
Q6. Name the NAVEL mnemonic for femoral vein access.
A: From lateral to medial under the inguinal ligament: Nerve (femoral), Artery (femoral), Vein (femoral), Empty space, Lymphatics.
Q7. What are the components of the bundle to prevent CLABSI?
A: (1) Hand hygiene; (2) Full barrier precautions (sterile gown, gloves, mask, cap, full drape); (3) Chlorhexidine 2% in 70% alcohol skin antisepsis; (4) Subclavian preferred over femoral; (5) Remove catheter as soon as not needed; (6) Daily review; (7) Antimicrobial-impregnated catheters in high-risk settings.
Q8. What is the treatment for inadvertent subclavian artery puncture during CVC insertion?
A: (1) Immediately remove needle; (2) Manual pressure is limited by clavicle - apply what pressure is possible; (3) If dilator/catheter placed in artery - do NOT remove - refer urgently to vascular surgery; (4) CT angiography to assess; (5) Endovascular or surgical repair. Never blindly pull a large-bore dilator from a non-compressible artery.
Q9. What is the significance of a "wandering" guidewire?
A: The guidewire should never be released fully from the operator's hand. Loss of guidewire into the circulation causes guidewire embolism, requiring fluoroscopic retrieval. Always maintain control of the proximal end.
Q10. In a patient with bilateral pneumothorax from trauma, which CVC site is preferred and why?
A: Femoral vein is preferred - it carries no pneumothorax risk and is completely unrelated to the thorax. If thoracic access is needed, subclavian is still usable if chest drains are already in situ on that side.
Q11. What are the CVP waveform components and what does each represent?
A: (A wave - atrial contraction; C wave - tricuspid valve bulging into RA; X descent - atrial relaxation; V wave - atrial filling during ventricular systole; Y descent - tricuspid valve opening). Absent A waves suggest AF. Giant V waves suggest tricuspid regurgitation.
Q12. What is the Seldinger technique? Who described it?
A: Described by Sven-Ivar Seldinger (1953). A needle punctures the vessel; a flexible guidewire is passed through the needle; the needle is removed; a catheter is threaded over the guidewire into the vessel; the wire is removed. This avoids the need to keep a sharp needle in the vessel during catheter insertion.
SOURCES
- Miller's Anesthesia, 10e (Gropper), Chapter 32 - Cardiovascular Monitoring
- Roberts and Hedges' Clinical Procedures in Emergency Medicine, Chapter 22 - Central Venous Access
- Fischer's Mastery of Surgery, 8e, Chapter 6 - Central Venous Cannulation Sites
- Pye's Surgical Handicraft, 22nd ed. - Complications of Central Venous Cannulation
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