Experimental Study On Biomechanical Property Of Adult Excised Porcine Trachea

OBJECTIVE:To investigate and evaluate the biomechanical property of adult excised porcine trachea, such as residual stress, bursting strength, radial pedestal, bending stiffness, stress-straining, stress relaxation and creep, providing the experimental methods and evidence for investigateing the biomechanical property of human trachea and tissue engineering artificial trachea.METHODS:The residual stress of tracheal membranous part and annulus cartilaginous were evaluated respectively by open-angle. And bursting strength of tracheal ring was evaluated when breaken through internal pressure. The TY8000 servo-handle tension test machine was used to measure the radial pedestal of 50mm tracheal sample when compressed. The TY8000 servo-handle tension test machine was used to measure the bending stiffness of 80mm trachea when compressed at midpoint of tube side and opposite side of membranous part respectively, record the force when compressed 20mm. The TY8000 servo-handle tension test machine was used to measure the stress-straining of 100mm-long tracheal annulus cartilaginous and tracheal membranous part respectively, draw the curve of stress-straining when the sample were elongated. The TY8000 servo-handle tension test machine was used to measure the stress relaxation and creep of tracheal annulus cartilaginous and tracheal membranous part. To record the change of stress time-variation while straining keeped invariably when the straining of tracheal annulus cartilaginous and tracheal membranous part achieve to 50﹪and 60﹪respectively .And to record the change of straining time-variation while stress keeped invariably when the stress of tracheal annulus cartilaginous and tracheal membranous part achieve to 20N and 2.5N. The software of MATLAB was used to imitate the experimental data, arriving at the equations of stress relaxation and creep.RESULTS:The residual stress was remained in the the adult excised porcine trachea. The open-angle, offer"C"shape, is about 40°when membranous part was cut, and the open-angle, offer"W"shape, is about from 38°to 215°when annulus cartilaginous was cut. T-test show sign difference of the open-angle is exist between the two trachel sample (P<0.01). The bursting strength from pharyngeal portion to eminence of the trachea: the average data of the pharyngeal portion is 180mmHg while the eminence is 110mmHg, and all ring cleavage were tracheal membranous part. The force of radial pedestal was measured when the diameter of trachea was compressed to 50%. The sample of trachea segment can gain reconversion as force was removed when compressed. The max force is 15.77N and the min force is 2.97N of transversal direction, the max force is 20.12N and the min force is 3.70N of vertical direction. T-test show no sign difference between the two sets date(P>0.05) . The sample of trachea segment can gain reconversion as force was removed when bented. The max force is 0.296N and the min force is 0.131N of ventri-direction, the max force is 0.254N and the min force is 0.150N of tube side direction. T-test show no sign difference between the two sets date(P>0.05). The curve of stress-straining of tracheal membranous part and tracheal annulus cartilaginous were described according to the date.The curve show the stress is tiny when straining is in the scope of 50%. Gain the performance data of the stress relaxation and creep of adult excised porcine tracheal annulus cartilaginous and membranous part. With the time increasing, stress is damping when strain is constancy, and strain is increasing when stress is constancy, the curve of stress and strain were parallel gradually.CONCLUTION:The residual stress was remained in the adult excised porcine no-load trachea. The residual stress of tracheal membranous part is larger than that of tracheal annulus cartilaginous. The residual stress increase gradually from annular cartilage to eminence, and the residual stress of annulus cartilaginous is ahout equal. The membranous of the excised porcine trachea will disrupt when the endospore pressure increases. The radial pedestal and bending are perfect in the excised porcine trachea. The stress-straining of the excised porcine trachea is elongated easily but breaken difficultly. The tracheal annulus cartilaginous and tracheal membranous part of adult excised porcine trachea possess the characteristics of stress relaxation and creep. The adult excised porcine trachea is tissue material with bioviscoelasticity.