Mechanical Analysis of Endotracheal Tubes

Abstract

An endotracheal tube (ETT) is a medical device that is crucial for the intubation process in order to deliver anesthesia and/or oxygen to a patient during a medical procedure. Device malfunctions, such as kinking, can lead to procedural complications, physical injury to the patient, or even patient death. The anesthesiology department at Nationwide Children’s Hospital has expressed concern regarding malfunction of a new model of ETT the hospital has recently adopted. While the anesthesiologists believe the performance of the cuff portion of the new ETT model, Halyard Microcuff Endotracheal Tube (Halyard Health), is more effective than the cuff of the previously used model, Shiley Hi-Lo Oral/Nasal Tracheal Tube Cuffed (formerly branded as Mallinckrodt; Medtronic, Inc.), they are concerned about the Halyard model’s increased susceptibility to kinking during a procedure. Therefore, this project aims to develop a repeatable mechanical test that is able to determine when a devastating ETT kink is occurring. This test will then be used to compare the mechanical properties of both the Halyard and the Shiley model ETTs under common conditions experienced in the clinic. These clinical conditions include a room (25C) and body temperature (36C), as well as oxygen airflow through the ETTs during mechanical testing. This pilot study has developed a repeatable mechanical testing procedure in order to determine the compression force and distance required to kink an ETT under different conditions. Results of this study showed that the force required to induce the devastating kink failure was determined to be lower for the heated testing conditions. Additionally the addition of airflow through the ETTs during compression testing confirms the occurrence of airway obstruction at approximately the same time a mechanical kink is observed on the force vs. distance curves. Further testing must be performed to determine statistically significant differences between ETT models and conditions. It is anticipated that the further results of this study will provide insight into which model of ETT anesthesiologists should choose to promote safer medical procedures, as well as potentially influence the design of future ETTs by their manufacturers.