Investigating Stress-relaxation and Failure Responses in the Trachea

Summary

The present protocol determines the tensile stress-relaxation and failure properties of porcine tracheae. Results from such methods can help improve the understanding of the viscoelastic and failure thresholds of the trachea and help advance the capabilities of computational models of the pulmonary system.

Abstract

The biomechanical properties of the trachea directly affect the airflow and contribute to the biological function of the respiratory system. Understanding these properties is critical to understanding the injury mechanism in this tissue. This protocol describes an experimental approach to study the stress-relaxation behavior of porcine trachea that were pre-stretched to 0% or 10% strain for 300 s, followed by mechanical tensile loading until failure. This study provides details of the experimental design, data acquisition, analyses, and preliminary results from the porcine tracheae biomechanical testing. Using the detailed steps provided in this protocol and the data analysis MATLAB code, future studies can investigate the time-dependent viscoelastic behavior of trachea tissue, which is critical to understanding its biomechanical responses during physiological, pathological, and traumatic conditions. Furthermore, in-depth studies of the biomechanical behavior of the trachea will critically aid in improving the design of related medical devices such as endotracheal implants that are widely used during surgeries.

Introduction

Despite its critical role in pulmonary disease, the largest airway structure, the trachea, has limited studies detailing its viscoelastic properties¹. An in-depth understanding of the time-dependent, viscoelastic behavior of the trachea is critical to pulmonary mechanics research since understanding the airway-specific material properties can help advance the science of injury prevention, diagnosis, and clinical intervention for pulmonary diseases, which are the third leading cause of death in the United States^2,3,4.

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Protocol

All methods described were approved by the Institutional Animal Care and Use Committee (IACUC) at Drexel University. All cadaveric animals were acquired from a United States Department of Agriculture (USDA)-approved farm located in Pennsylvania, USA. A cadaver of a male Yorkshire pig (3 weeks old) was used for the present study.

1. Tissue harvest

1. Acquire a cadaver of a pig from an approved farm and perform the experiments within 2 h from euthanasia. Keep the cadave.......

Discussion

Very few studies have reported the stress-relaxation properties of the trachea^21,23. Studies are needed to further strengthen our understanding of the time-dependent responses of the tracheal tissue. This study offers detailed steps to perform such investigations; however, the following critical steps within the protocol must be ensured for reliable testing: (1) proper tissue hydration, (2) similar tissue-type (number of cartilaginous rings and muscle) distributi.......

Materials

Name	Company	Catalog Number	Comments
Disposable safety scalpels	Fine Science Tools Inc	10000-10
eXpert 7600	ADMET Inc.	N/A	Norwood, MA
Forceps	Fine Science Tools Inc	11006-12 and 11027-12 or 11506-12
Gauge Safe	ADMET Inc.	N/A	Free Download
Image J	NIH	N/A	Open Source
Proramming Software - MATLAB	Mathworks	N/A	version 2018A
Scissors	Fine Science Tools Inc	14094-11 or 14060-09
Sterile phosphate buffer solution	Millipore, Thomas Scientific	MFCD00131855