Long-versus Short-Axis Ultrasound Guidance for Subclavian Vein Cannulation
Condition: Vascular Access Complication; Perioperative/Postoperative Complications
MeSH terms: Postoperative Complications
Study type: Interventional

Summary: 
      Central venous catheterization is commonly applied in patients undergoing cardiac surgery.
      The subclavian vein has lower risk of infection and provides more patients comfort. However
      central venous catheterization may results in complications such as pneumothorax, hemothorax
      or arterial puncture. It has been suggested that ultrasound (US) guidance could improve the
      success rate, reduce the number of needle passes and decrease complications. Two different
      real-time 2-dimensional US techniques can be employed in the insertion of central venous
      catheters. The first technique involves real-time US-guided cannulation of subclavian vein
      using a long axis/in-plane approach. The second one involves real-time US-guided using a
      short axis/out-off-plane approach. However to date no studies have compared their efficacy
      and safety. The purpose of this study was to compare the US-guided long-axis versus
      short-axis approach for the SCV catheterization in adult critical care patients.
    

Detailed description: 
      The two techniques used for vessel visualization are far different:

      The Short-Axis (SA) approach attempts to view the vessel in cross-section while venous access
      is obtained. The strength of the SA approach is that the vein is centered under the
      transducer and that the midpoint of the transducer becomes a reference point for the
      insertion of the needle, and that at the same time is possible to visualize SC artery and the
      pleural line. SA approach is easy to learn by novice sonologists.

      The Long-Axis (LA) approach employs a technique that views the length of the vessel during
      cannulation.For this reason, with LA approach is possible to visualize the needle advance
      during the entire procedure from the soft tissues until the lumen of the vein, but SC artery
      and pleural line are not visualized in the same scan. For LA approach, practice is required
      to keep the needle precisely within the image and care must be taken to avoid the probe
      inadvertently moving away from the target structure.
    

Intervention name(s): Long Axis strategy; Short Axis Strategy
Intervention type(s): Device; Device
Intervention description(s): With the long-axis approach the vein appeared in the longitudinal view. With this approach only the vein was visible on the screen. The needle was held at a 30° angle, oriented in-plane with the transducer and the skin punctured at the base of the transducer. The vessel alignment was maintained during the procedure and the entire length of the needle was visible during the progression through the tissues.; With the short-axis approach the probe was positioned almost perpendicularly to the clavicle. The needle was held at an angle of 45° relative to the skin surface and sagittal to the plane of the probe (out-of-plane). During the progression to the vessel, the visualization of the needle was limited to the deformation of tissue and artefacts produced by needle advancement. When the tip abutted the vein wall, additional pressure produced transient vessel deformation, which disappeared once the wall was penetrated.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Supportive Care
Keywords: central venous access; ultrasonography; subclavian vein; pneumothorax; vessel view