It is Possible to Cause Damage to a Laser Fibre during Delivery of Tumescent Anaesthesia for Endovenous Laser Ablation (EVLA)

AimsTo establish a possible mechanism of damage to a laser fibre significant enough to cause a retained segment within a patient.MethodsA 21 G needle was used to pierce a VARILASE™ 810 nm Laser Fibre inserted within a 4F sheath. A tiny pin source of light from the aiming beam emerged from the needle hole in the sheath. Using laser protection protocol, the generator was fired for one minute at 14 Watts (W) continuous wave. The sheath and fibre were then examined. In a control experiment, we were unable manually to break a fibre where the coating had been damaged prior to the laser being fired.ResultsThe aiming beam was noted to be concentrated at the side of the catheter at the point of needle damage rather than at the fibre tip. When the fibre was removed from the sheath the distal length, from the point of damage to the tip, was retained within the sheath. Longer firing with the sheath surrounded by a wet towel or a pork loin resulted in complete severance of the sheath and fibre.ConclusionThere are no firm manufacturer's guidelines on whether Tumescent Anaesthesia should be delivered before or after the laser fibre has been inserted into the patient. Some units performing EVLA prefer to do this with the laser fibre in situ as it is easier to image on ultrasound than the sheath alone. The results of this in-vitro experiment would suggest it is possible to cause sufficient needle damage to fracture a laser fibre when fired. In the interests of safety we would recommend administration of tumescent anaesthesia should always be carried out before introduction of the laser fibre.