Dr. TSAI, NGA WING POLLY; Supervisor: Dr WM CHAN, Adult Intensive Care Unit, Queen Mary Hospital
Background:
Central venous (CV) access in ICU setting is often obtained through either internal jugular, subclavian or femoral veins. This technique is usually based on landmarks in the pre-ultrasound era. Subclavian vein catheterization is associated with failure and complications due to injury to the nearby lung parenchyma and subclavian artery. Femoral vein approach is associated with increased risk of line sepsis. The axillary vein lies outside of the thoracic cage and can be easily imaged. It is a potentially new ICU approach, especially for those patients with head and neck pathologies. In fact, many local cardiologists are now inserting pacing wires via the axillary vein puncture under fluoroscopic guidance (as a widely used technique) rather than via the subclavian vein. In various overseas small scale studies, there is a minimal risk of pneumothorax, and the observed occasional puncture of the axillary artery can be easily handled by manual compression. At present, no large study or local data is available to assess the potential of this technique.
Methods:
A descriptive, prospective and observational study of a series of cases, describing the success rate with ultrasound guided procedure, and the possible complications arising from axillary vein cannulation. The degree of experience will be stratified into 2 tiers based on the cumulative number of axillary lines inserted by each operator.
Results:
A total of 30 patients were enrolled during a 9 month period from July 2010 to March 2011. The overall failure rate was 3.3%. Experienced hands had a shorter drape to venous puncture time (120 seconds vs 240 seconds, P=0.009). There was no reported case of catheter related bloodstream infection, pneumothorax or nerve injury. Inadvertent arterial puncture occurred in 10% of case, all by inexperienced hands, which was managed by manual compression without consequence. Axillary vein depth was associated with overweight (defined as body mass index > 25kg/m2) (2.45cm vs 1.88cm, P=0.033). Vein diameter, however, was not associated with body build or blood pressure. Right sided cannulation tended to have a higher chance of malposition into the internal jugular vein.
Conclusion:
Transpectoral ultrasound guided catheterization of the axillary vein offers a reasonable good choice to traditional methods of central venous cannulation by bedside in the ICU setting, with few complications noted. It shares the advantages of the subclavian approach but reduces the risk of pneumothorax or hemothorax due to its extra-thoracic position. The utilization of 2D ultrasonography in identifying the axillary vein further reduces the risk.