Does Longitudinal or Transverse Orientation of Ultrasound Probe Improve Cannulation Success in Minimally Invasive Venous Surgery. A Randomized Controlled Trial.

Varicose veins are an extremely common disorder and negatively impact on patient quality of life. In recent years minimally invasive venous treatments for varicose veins (MIVT) have emerged as an effective alternative to open surgery. It is associated with a reduction in peri-operative morbidity, recovery time and increased quality of life scores when compared with open surgical stripping4. Furthermore, MIVT is now widely carried out under local anaesthesia.

Typically, MIVT requires cannulation, under ultrasound guidance, of either the great or small saphenous vein in the lower extremity to allow subsequent passage of a venous catheter. This cannulation technique is widely used for venous and arterial cannulation throughout the body. It entails utilising an ultrasound probe in either a longitudinal or transverse orientation (to the target vein) to guide an entry needle into a target vessel. The longitudinal orientation, while unstable, offers better visualisation of the vein when performed accurately. Conversely, the transverse approach is very stable with poorer visualisation of the target vessel. As such, no definitve guidance is available to guide treating physicians as to the optimal orientation with a wide variation among practitioners.

The cannulation process for MIVT is often further challenged by both the small calibre and tendency toward vasospasm of target veins. Failure of cannulation may result in greater rates of conversion to open surgery exposing the patient to the the higher rate of morbidity associated with open surgery. More importantly, repeated cannulation results in significant discomfort and hence a reduction in patient satisfaction.

Longitudinal ultrasound orientation during venous cannulation has been suggested by a number of radomised studies to offer superior cannulation rates of cannulation. This technique may offer a simple, safe and cost-neutral step to improve cannulation rates in the widely performed MIVT.

The authors propose a blinded randomized controlled study to investigate the effects of ultrasound orietation on cannulation rates in MIVT. To test this hypothesis we plan to randomise 100 patients undergoing MIVT to either venous cannulation with transverse or longitudinal orientation of the ultrasound probe.