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UCSD Med Intubation

Spring 2017 MAE 156B Sponsored Project

University of California, San Diego

Project Team Members: Emeline Lee, Wendy Lin, Brendon Lim

Sponsored by Dr. Jae Kim and Dr. Daniel Lee of the UCSD Jacobs Medical Center

Introduction

Premature infants sometimes require respiratory support for their survival, requiring an intubation procedure, which is the insertion of an endotracheal tube to allow for mechanical ventilation to assist in breathing. This procedure uses a laryngoscope to allow an endotracheal tube to pass through a small opening from the vocal cords to the lungs. Every year, a few hundred intubation procedures are performed on infant patients at the UCSD Jacobs Medical Center. With each intubation procedure, there is a risk of perforating the infant's interior and of multiple failed attempts, both leading to the possibility of death. Doctors from the UCSD Medical Center recognized the need to improve on the current methods of intubation and allow for a method to standardize the procedure for future research and training. Dr. Jae H. Kim, MD, Ph.D. and Dr. Daniel Lee, MD, Ph.D. have asked UC San Diego’s Mechanical and Aerospace Engineering Department to design and create an intubation ramp to allow for better visualization of the vocal cords and an optimization of the laryngoscope design to better control the endotracheal tube. 

Project Objectives

• • Create a ramp to prop an infant’s neck in a position to optimize the view of the patient’s trachea.

    • Hold infant weight of 300 grams to 4.5 kilograms.

    • Provide comfort for the infant.

    • Allow for the simple change in the angle between the two faces of the ramp.

    • Must be disposable or easily sanitized.

  • Modify a laryngoscope design to allow for control of the endotracheal tube.

    • Allow for visualization of the vocal cords.

    • Guide endotracheal tube to vocal cords .

    • Allow for easy release of the tube after insertion.

• Allow for recording of the ramp angle to allow for standardization of the procedure and allow for statistical data.

Final Design

The final design solution was categorized into two parts: the ramp and modified laryngoscope.

Part 1: Ramp

The ramp surface is comprised of two polycarbonate slats connected by adjustable locking hinges that provide locking at 10 degree increments. Once locked, the hinge becomes a rigid joint and is able to withstand 56.49 Newton-meters of torque. The polycarbonate slats and locking hinges are attached to aluminum supports with rounded plastic ends to reduce the friction between the ramp and the surface it rests on. The locking joint has tick marks displaying the angle of rotation and the angle the infant’s head will tilt back for optimal visualization of the vocal cords. The surface of the ramp is lined with neoprene foam rubber to provide a thin cushioned surface where the patient will lie. A clear vinyl cover is fitted over the ramp for protection against contamination such as bodily fluids.

Part 2: Laryngoscope

The final design of the laryngoscope uses a cylindrical attachment to guide the endotracheal tube down the throat. The attachment acts as a backboard, allowing the endotracheal tube to achieve more stiffness without the use of the endotracheal tube stylet. The backboard is curved slightly to push the tongue out of the way and provide better visualization for the doctor. This blade attachment also has a decreasing diameter that helps overcome the sharp angle needed to guide it in between the vocal cords. The adaptation allows for guidance of the tube without the risk of puncturing the patient’s throat.

Performance Results

Part 1: Ramp

The ramp was able to withstand the 45 Newton (10 lb weight) requirement asked for this project. The testing also showed that because of the occipital bone of the infant (the bulge of the infant's head on the backside) the angle of rotation is proportional and not directly equal to the angle of the infant's neck tilt. Every infant's occipital bone size is different; however, the numerical value of the angles are not so important if that angle can be replicated for that infant for the next intubation procedure. From testing, it was observed that for the above infant mannequin (2 kg) to have an optimal neck tilt of 45 degrees, the ramp had to have a 60 degree angle of rotation.

Part 2: Laryngoscope

In order to test the final design of the laryngoscope, it was used on an infant intubation head. Five medical professionals tested the 3D printed ABS model to verify its effectiveness. They experienced finer control of the endotracheal tube while it was in the mouth, and testified that the tube was easily inserted through the vocal cords into the trachea. One person agreed that although the intubation process was made easier with this design, smaller infants would require an attachment with a reduced radius in order to fit in the mouth. In the figure below, the final laryngoscope design was tested to ensure it would fit in a 3.5 kg infant’s mouth.

Click to view Executive Summary