Development of safe and effective radio frequency (RF) vessel sealing devices requires the complete characterization of thermal damage that can occur adjacent to areas of energy application. Hematoxylin and eosin (H&E) staining is an efficacious and extensively used histological test method for assessing this lateral thermal damage through characterization of changes in cell and tissue morphology. The purpose of this investigation was to compare thermal spread measurements obtained using H&E staining to measurements made using picrosirius red (PSR) staining, an alternative histological test method that exploits the birefringence of healthy vascular collagen to facilitate the identification of thermal damage associated with use of vessel sealing devices. A 5 mm RF vessel sealing device was used to seal arteries in vivo in various porcine tissues. Subsequently, sealed vessel segments were excised and histologically processed. Paired histological sections were mounted on slides; one section was stained with PSR and one section was stained with H&E. A blinded board-certified veterinary pathologist completed thermal spread measurements on all PSR- and H&E-stained sections. Bland–Altman comparison plots were then used to estimate any bias between the two measurement methods, as well as quantify the range of differences between PSR and H&E thermal spread measurements. The magnitude of the mean difference between measurements was determined to be less than 0.10 mm and, with 90 % confidence, 95 % of the differences between measurements were within 1.0 mm. These results indicate that PSR-staining is an appropriate alternative to H&E-staining for the measurement of lateral thermal spread associated with an RF vessel sealing device.

Burst pressure and thermal spread are two key performance characteristics associated with the development of safe and effective energy-based vessel sealing and tissue transection devices. A thorough literature review revealed that a large percentage of studies describing assessments of burst pressure or thermal spread, or both, used univariate, single-factor inferential statistics as the primary source of analysis, with the Student’s t-test and one-way ANOVA being the most prevalent methods. In addition, there were only two examples of studies that discussed the approach for handling two correlated halves of a vessel seal created by vessel sealing and dividing devices. Use of analysis methods such as those described can result in a problematic mixing of known and unknown variability, as vessel diameter, specific device used, test gauge, particular tissue properties, and several other factors potentially have an impact on burst and thermal spread measurements. The consequences of this are potential confounding, a lack of sensitivity when comparing groups, and a general inability to better understand the factors and interactions involved with optimizing overall seal performance. This paper describes a study evaluating the performance of four energy-based vessel sealing devices, and it outlines the comprehensive method used for analyzing burst pressure and thermal spread measurements obtained from these devices. This approach incorporates covariates into the analysis, increasing overall study power and facilitating an enhanced understanding of experimental noise factors. Higher sensitivity in the analysis and identification of key experimental factors contributing to variability allows the utilization of an evidence-based approach to continuously improve test and analysis methods, and complete successive design iterations for the development of consistently safe and effective vessel sealing and tissue transection devices. Results from this comprehensive analysis method have been included in multiple domestic and international regulatory submissions.