Background: Energy-based surgical scalpels are designed to efficiently transect and seal blood vessels using thermal\r\nenergy to promote protein denaturation and coagulation. Assessment and design improvement of ultrasonic scalpel\r\nperformance relies on both in vivo and ex vivo testing. The objective of this work was to design and implement a\r\nrobust, experimental test matrix with randomization restrictions and predictive statistical power, which allowed for\r\nidentification of those experimental variables that may affect the quality of the seal obtained ex vivo.\r\nMethods: The design of the experiment included three factors: temperature (two levels); the type of solution used\r\nto perfuse the artery during transection (three types); and artery type (two types) resulting in a total of twelve\r\npossible treatment combinations. Burst pressures of porcine carotid and renal arteries sealed ex vivo were assigned\r\nas the response variable.\r\nResults: The experimental test matrix was designed and carried out as a split-plot experiment in order to assess\r\nthe contributions of several variables and their interactions while accounting for randomization restrictions present\r\nin the experimental setup. The statistical software package SAS was utilized and PROC MIXED was used to account\r\nfor the randomization restrictions in the split-plot design. The combination of temperature, solution, and vessel\r\ntype had a statistically significant impact on seal quality.\r\nConclusions: The design and implementation of a split-plot experimental test-matrix provided a mechanism for\r\naddressing the existing technical randomization restrictions of ex vivo ultrasonic scalpel performance testing, while\r\npreserving the ability to examine the potential effects of independent factors or variables. This method for\r\ngenerating the experimental design and the statistical analyses of the resulting data are adaptable to a wide\r\nvariety of experimental problems involving large-scale tissue-based studies of medical or experimental device\r\nefficacy and performance.
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