Portable Equine Lung Function Measuring Device
Portable Equine Lung Function Measuring Device
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A portable medical device to diagnose respiratory disease in horses
Capstone Project (Tufts BS) - Product Development
Background
Background
Equine asthma is endemic in stabled horses of all ages, often attributed from the dusty environmental conditions of stables. It is characterized by the inflammation and remodeling of the airways as well as increased mucus in the lungs, all of which, similarly to asthma in humans, result in decreased respiratory function and consequent poor performance. Currently, there is a push in equine medicine to better categorize the subtypes of asthma to provide individualized treatment plans. Yet, respiratory diagnostic methods presently used for horses have their challenges; the gold standards provide accurate respiratory information, but are invasive, difficult to use, and not portable. Portable, non-invasive methods do exist, but lack in robustness, accuracy of data, and safety.
Image Accessed 2024, spurbroke
Task
Task
In collaboration with the Tufts Cummings School of Veterinary Medicine, my team was tasked with developing a medical device prototype to measure the hydrodynamic resistance of a horse's lungs to diagnose respiratory diseases. The device needed to consider the pain points of the customer, Dr. Mazan, while also considering the needs and communication limitations of a 1,000 lb patient.
Designing the System
Designing the System
Before building anything, my team set out to better understand our customers and their patients: horses. Through several interviews and in-person visits to the hospital, we developed a prioritized list of customer needs and requirements to inform our product's design. Functionality, robustness, and portability emerged as the key guiding needs. Additionally, it was critical to ensure that the device could not harm the horse or others around it, especially if the animal was startled. Below is a matrix of customer needs and design requirements.
Customer Needs and Design Requirements Matrix
Designing a medical device for animals presents a unique challenge due to the language barrier; you can't instruct a horse to exhale forcefully like you can with humans. However, the challenges of designing for young children, who also have limited communication, helped guide our approach. Based on our research, we adapted the Respiratory Flow-Interruption method, commonly used with infants, for diagnosing equine asthma. This method involves temporarily interrupting airflow during a breath, allowing the pressure inside the lungs to equalize with the pressure at the nose. By measuring this nose pressure before interruption, and calculating its ratio to the airflow, we can determine the airway resistance of the patient, a key indicator of respiratory diseases. Below is graphical visual of the change in pressure during interruption of the breath as well as the airway resistance ratio.
Change in Pressure During Interruption of Breath
While considering the needs and design requirements, my team moved forward with adapting the Respiratory Flow-Interruption method for our equine product. We constructed a Work Break-Down Structure and Gantt Chart to organize our efforts. Additionally, as a team we divided up the work along the product's three sub-systems: 1) mask, 2) pressure sensing and interruption, and 3) flow sensing and data acquisition.
Product Schematic
Specifically, I worked on the flow sensing portion of the product. I conducted horse respiration fluid experimentation and analysis to better understand the expected flow profiles of a horse's breath. These results guided the design of the product's flow tube and informed the selection of our flow sensor. After experimentation to calibrate the sensor, I then selected and programmed the microcontroller and DAQ system to measure air flow at the required sampling rate and resolution. After attempting to adapt anemometer(s) and ultra-sonic transducers to measure volumetric flow within a budget, we ultimately selected a pneumotach for our flow sensing.
Flow Testing With Horse
Flow Profile Testing
Flow Calibration
Additionally, I contributed to designing the interruption system for the pressure sensing sub-system, which our requirements specified the use of a pneumatic shutter for breath interruption. We developed the system to use 60 psi of pressurized air from a small 3000 psi paintball canister to actuate the shutter at an operator's discretion. A pneumatic solenoid, MOSFET, microcontroller, and operator switch work together to control the shutter state and timing intervals.
Shutter Controller
Pneumatic Shutter System
Breath Interruption
Pressure and Flow Systems
Results
Results
After dead ends, design re-configurations, and challenges with COVID, we ultimately were able to complete a fully functioning product. Doctors at the Tufts Hospital for Large Animals have been loving its performance, and it's accuracy and precision are currently being tested against gold-standard methods across several trials. In fact, the product has been featured in various news outlets and the Journal of Applied Physiology and currently is patent-pending.
Final Product
Product Testing
Image Accessed 2024, WO2023220629A1
Image Accessed 2024, Journal of Applied Physiology
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