Indications

• Peripheral venous access is required for:
  • Administration of fluids
  • Administration of drugs
• Central venous access is required for:
  • Parenteral nutrition
  • Monitoring of central venous pressure
  • Cardiac pacing
  • Difficult peripheral access

Techniques

• Aseptic techniques should be used for all cannulations
• Local anaesthetic should be used for central catheters
• Success may be improved by using ultrasound guidance
• Techniques of gaining access include:
  • Catheter over needle
  • Catheter through needle
  • Seldinger technique
  • Surgical cutdown

Seldinger technique

• There are four steps to the Seldinger technique
  • Venepuncture is performed with a introducer needle
  • A soft tipped guide wire is passed through the needle and the needle removed
  • A dilator is passed over the guide wire
  • Dilator is removed and catheter is passed over wire and wire is removed
• Chest x-ray should be performed to check position of catheter

Venous cutdown

• Useful for gaining access in shocked hypovolaemic patient
• Commonest sites used are:
  • Long saphenous vein at ankle - 2 cm anterior to medial malleolus
  • Basilic vein at elbow - 2.5 cm lateral to medial epicondyle
• At both sites vein is dissected and ligated distally
• Small transverse venotomy is made
• Cannula is passed through venotomy and secured

Anatomy of venous access

• Internal jugular vein
  • Right sided access preferred
  • Apical pleura does not rise as high on right and avoids thoracic duct
  • Patient positioned head down
  • In the low approach triangle formed by two heads of sternomastoid and clavicle identified
  • Cannula aimed down and lateral towards ipsilateral nipple
• Subclavian vein
  • Usually approached from below clavicle
  • Patient positioned head down
  • Needle inserted below junction of medial 2/3 and lateral 1/3 of the clavicle
  • Needle aimed towards suprasternal notch
  • Passes immediately behind clavicle
  • Vein encountered after 4-5 cm

Early complications

• Haemorrhage
• Air embolus
• Pneumothorax
• Cardiac arrhythmias
• Pericardial tamponade
• Failed cannulation

Late complications

• Venous thrombosis
• Infection

Central line infection

• 10% of central lines become colonised with bacteria
• 2% of patients in ITU develop catheter-related sepsis
• Usually due to coagulase-negative staphylococcus infection
• Occasionally due to Candida and Staph. aureus
• Infection can be prevented by aseptic techniques and adequate care of lines
• Closed systems should be used at all times
• Dedicated lines should be used for parenteral nutrition
• Antimicrobial coating of lines may reduce the risk of infection

Bibliography

Muhm M.  Ultrasound guided central venous access.  Br Med J 2002;  325:  1373-1374

Polderman K H,  Girbes A R J.  Central venous catheter use:  mechanical complications.  Intensive Care Med 2002;  28:  1-17.

Polderman K H,  Girbes A R J.  Central venous catheter use:  infectious complications.  Intensive Care Med 2002;  28:  18-28.