In vivo laser tissue welding in the rabbit maxillary sinus.

Background: One of the challenges in the current expansion of endoscopic sinonasal surgery is the ability to adequately reconstruct the skull base. Laser tissue welding (LTW) uses laser energy coupled to a biological solder to produce tissue bonds with burst thresholds exceeding human intracranial pressure. This technology could be used to reduce the rate of postoperative cerebrospinal fluid (CSF) leak. We performed this study to determine whether LTW can create durable tissue bonds in sinonasal mucosa that support normal wound healing and produce minimal collateral thermal injury.

Methods: Bilateral maxillary sinus mucosal incisions were made in 20 New Zealand white rabbits and one side was repaired using LTW. Burst pressure thresholds were measured on postoperative days 0, 5, and 15 and were compared with control using a two- way ANOVA and a post hoc Tukey test. Welds were examined histologically for thermal injury, inflammation, and fibroplasia and graded on a 4-point scale by three blinded observers.

Results: The burst pressures of the LTW group were significantly higher than control on postoperative day 0 (120.85 mm Hg, N = 4, SD = 47.84 versus 7.85 mm Hg, N = 4, SD = 0.78), and day 5 (132.56 mm Hg, N = 8, SD = 24.02 versus 41.7 mm Hg, N = 8, SD = 7.2; p < 0.05). By postoperative day 15 there was no significant difference between LTW (169.64 mm Hg, N = 8, SD = 18.49) and control (160.84 mm Hg, N = 8, SD = 14.16) burst thresholds. There was no evidence of thermal injury to the surrounding tissue in any group as well as no difference between experimental group and control with respect to inflammation or fibroplasia.

Conclusion: This is the first in vivo study showing that LTW is capable of producing tissue bonds exceeding human intracranial pressure with negligible thermal injury in sinonasal tissue. Welding can be performed endoscopically using a fiberoptic cable and may be useful in CSF leak and skull base repair.