Safety and cost-effectiveness of single-use endolaser probe reprocessing in vitreoretinal surgery

Background Endolaser probes have been designed and sold for single-use only. However, in Brazil, they are not included in the list of single-use medical products that are prohibited from being reprocessed and could potentially be reused if safety requirements are accomplished. Therefore, this study aimed to determine and compare the quality, safety and costs of reprocessed versus original single-use endolaser probes of a specific brand and model. Methods The study, conducted at a university hospital in Sao Paulo, Brazil, was divided in two phases. The first one tested the feasibility, sterility and physical integrity of ten reprocessed laser probes. In the second phase, all vitrectomy procedures using endolaser probes (reprocessed and original ones) from August 2017 to October 2019 were evaluated. The operated cases were followed for any signs of infection and number of defective probes for each group were counted. The cost of acquiring a new probe and for all reprocessing stages were evaluated and quantified in US dollars($). Results Microbiologic, residual ethilen oxide and microscopic evaluation of integrity of reprocessed laser probes were all within acceptable range. The second phase of this study included 590 endolaser probes, of which 375 were original and 215 were reprocessed. Functionality rates differed significantly between groups. Among the original probes, 373 (99.47%) were functioning and 2 (0.53%) were non-functioning. Among the reprocessed ones, 201 (93.5%) were functioning and 14 (6.5%) were non-functioning (p < .001). The average cost of one reprocessing was $3.00, and the average cost of an original probe was $150.00. Considering the loss rates, potential savings were $147.60 for each once-reprocessed probe. The frequency of infectious endophthalmitis was null in both groups. Conclusions Our study showed that a single cycle endolaser probe reprocessing was safe and efficient, not associated with increase in endophthalmitis rate and proved to be significantly cost-effective, even considering a greater malfunction rate when compared to the original devices.

Image guidance based on MRI for spinal interstitial laser thermotherapy: technical aspects and accuracy

OBJECTIVEImage guidance for spinal procedures is based on 3D-fluoroscopy or CT, which provide poor visualization of soft tissues, including the spinal cord. To overcome this limitation, the authors developed a method to register intraoperative MRI (iMRI) of the spine into a neuronavigation system, allowing excellent visualization of the spinal cord. This novel technique improved the accuracy in the deployment of laser interstitial thermal therapy probes for the treatment of metastatic spinal cord compression.METHODSPatients were positioned prone on the MRI table under general anesthesia. Fiducial markers were applied on the skin of the back, and a plastic cradle was used to support the MRI coil. T2-weighted MRI sequences of the region of interest were exported to a standard navigation system. A reference array was sutured to the skin, and surface matching of the fiducial markers was performed. A navigated Jamshidi needle was advanced until contact was made with the dorsal elements; its position was confirmed with intraoperative fluoroscopy prior to advancement into a target in the epidural space. A screenshot of its final position was saved, and then the Jamshidi needle was exchanged for an MRI-compatible access cannula. MRI of the exact axial plane of each access cannula was obtained and compared with the corresponding screenshot saved during positioning. The discrepancy in millimeters between the trajectories was measured to evaluate accuracy of the image guidanceRESULTSThirteen individuals underwent implantation of 47 laser probes. The median absolute value of the discrepancy between the location predicted by the navigation system and the actual position of the access cannulas was 0.7 mm (range 0–3.2 mm). No injury or adverse event occurred during the procedures.CONCLUSIONSThis study demonstrates the feasibility of image guidance based on MRI to perform laser interstitial thermotherapy of spinal metastasis. The authors' method permits excellent visualization of the spinal cord, improving safety and workflow during laser ablations in the epidural space. The results can be extrapolated to other indications, including biopsies or drainage of fluid collections near the spinal cord.

Experimental investigation on stainless steel welding with a 15 kW fibre laser

In the present study, attenuation of the laser beam because of the induced plume during bead-on-plate welding of an austenitic stainless steel plate with a 15 kW fibre laser beam, was investigated to better understand laser welding phenomena. A high-speed video camera was used to monitor the plume and keyhole behaviour. Attenuation and refraction levels, due to the induced plume, were measured by different wavelengths laser probes. Finally, a high resolution spectrometer was used to analyze spectral emission from the induced plasma plume by the fibre laser beam. The Boltzmann plot method was used to estimate the temperature of laser-induced plasma plume and Saha’s equation was applied to calculate the ionization degree.