Harmonic Scalpel Versus Flexible Co2 Laser for Tongue Resection: A Histopathological Analysis of Thermal Damage in Human Cadavers

Abstract

Objectives: To compare thermal damage caused by Harmonic scalpel and CO2 laser to cadaveric tongue. Methods: Two fresh human cadaver heads were enrolled for the study. Oral tongue was exposed and incisions were made in the tongue akin to a tongue tumor resection using the harmonic scalpel and flexible C02 laser fiber at various settings recommended for surgery. The margins of resection were sampled, labeled, and sent for pathological analysis to assess depth of thermal damage calculated in millimeters. The pathologist was blinded to the surgical tool used. Control tongue tissue was also sent as a baseline for comparison. Results: Three tongue samples were studied to assess depth of thermal damage by harmonic scalpel. The mean depth of thermal damage was 0.69 mm, (range, 0.51 -0.82 mm). Five tongue samples were studied to assess depth of thermal damage by CO2 laser. The mean depth of thermal damage was 0.3mm, (range, 0.22 to 0.43mm). As expected, control samples showed 0 mm of thermal damage. There was a statistically significant difference between the depth of thermal injury to tongue resection margins by harmonic scalpel as compared to CO2 laser, (p=0.003). Conclusion: In a cadaveric model, flexible CO2 laser fiber causes less depth of thermal damage when compared with harmonic scalpel at settings utilized in our study. However, the relevance of this information in terms of wound healing, hemostasis, safety, costeffectiveness, and surgical outcomes needs to be further studied in clinical settings.The CO2 laser was first introduced into Otolaryngology by Jako and Strong in 1972 2. The laser can be an excellent tool for anterior oral cavity and anterior oral tongue resections. However, the bulk and cumbersome delivery system makes its use less attractive. 1,2 With the advent of the photonic band gap fiber assembly (PBFA), a flexible fiber CO2 delivery system developed by Omniguide Inc, it is now possible to overcome these limitations. 2,7 The PBFA system allows the direct delivery of CO2 energy to regions in the head and neck where direct visualization is limited. A variety of hand pieces allow laser energy to be provided along the plane of surgical dissection and in sync with the surgeon's line of sight. This facilitates precise surgery. In addition to increased maneuverability, a variable rate of gas is transmitted through the hollow core of the PBFA creating the added benefits of cooling the surgical site and clearing the field of debris, plume and blood. 2,7 The current limitations of the flexible CO2 laser fiber include a learning curve associated with its use, the PBFA also can be damaged if not used correctly, the tip of the fiber is not robust enough to serve as a surgical dissector, and inefficient with respect to coagulation (vessels up to 1-2mm in diameter). 1,2The new PBFA fiber can easily be focused to improve cutting and also defocused to coagulate by moving the tip of the laser fiber closer to the target or away from it 1 . However, a true assessment of the lasers utility and ease of use...

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