Design of a factorial experiment with randomization restrictions to assess medical device performance on vascular tissue

BMC Medical Research Methodology

Margaret F Pinnell²  Carissa M Krane³  Wiebke S Diestelkamp¹ 

[1] Department of Mathematics, University of Dayton, 300 College Park Ave., Dayton, OH 45469, USA;Department of Mechanical and Aerospace Engineering, University of Dayton, 300 College Park Ave., Dayton, OH 45469, USA;Department of Biology, University of Dayton, 300 College Park Ave., Dayton, OH 45469, USA

关键词: burst pressure;    biostatistics;    vascular;    split-plot design, randomization restrictions;    Factorial design;   

Others  :  1140200
DOI  :  10.1186/1471-2288-11-75

 received in 2010-05-10, accepted in 2011-05-20,  发布年份 2011

【 摘 要 】

Background

Energy-based surgical scalpels are designed to efficiently transect and seal blood vessels using thermal energy to promote protein denaturation and coagulation. Assessment and design improvement of ultrasonic scalpel performance relies on both in vivo and ex vivo testing. The objective of this work was to design and implement a robust, experimental test matrix with randomization restrictions and predictive statistical power, which allowed for identification of those experimental variables that may affect the quality of the seal obtained ex vivo.

Methods

The design of the experiment included three factors: temperature (two levels); the type of solution used to perfuse the artery during transection (three types); and artery type (two types) resulting in a total of twelve possible treatment combinations. Burst pressures of porcine carotid and renal arteries sealed ex vivo were assigned as the response variable.

Results

The experimental test matrix was designed and carried out as a split-plot experiment in order to assess the contributions of several variables and their interactions while accounting for randomization restrictions present in the experimental setup. The statistical software package SAS was utilized and PROC MIXED was used to account for the randomization restrictions in the split-plot design. The combination of temperature, solution, and vessel type had a statistically significant impact on seal quality.

Conclusions

The design and implementation of a split-plot experimental test-matrix provided a mechanism for addressing the existing technical randomization restrictions of ex vivo ultrasonic scalpel performance testing, while preserving the ability to examine the potential effects of independent factors or variables. This method for generating the experimental design and the statistical analyses of the resulting data are adaptable to a wide variety of experimental problems involving large-scale tissue-based studies of medical or experimental device efficacy and performance.

【 授权许可】

   
2011 Diestelkamp et al; licensee BioMed Central Ltd.

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