A better and inexpensive way of observing
Fetal Heart Rate
Introduction
Nathan Bair was doing research in developing countries and discovered that there was a need for a better, less expensive way of observing fetal heart rate in these poor countries. The measurement of fetal heart rate provides information that is critical to medical personnel and mothers in order to properly monitor a baby’s health. An abnormal fetal heart rate can indicate that the baby is not getting enough oxygen and an emergency cesarean section could save the baby. Fetal heart rate accelerations and decelerations are also typically measured during labor to make sure that the baby is receiving adequate oxygen and that the baby's head or umbilical cord aren't compressed and cutting off the oxygen supply. Fetal heart rate monitoring during labor can also indicate whether or not the baby is in a safe position to continue a normal delivery. Moreover, it becomes even more important for high-risk pregnancies, common amongst women with conditions such as elevated blood pressure and problematic fetal growth, both highly existent issues in developing countries.
Background
Today, many developed nations employ hand held doppler systems and wearable sensors. While they often come with supplementary features such as a display that shows battery life and signal quality, user replaceable cables, and ergonomic designs, they consequently come with a high price.
We found the Summit Doppler LifeDop 250 unit (image to the right) listed for $652.73, for example. There are several less expensive options available for between $40 and $60 but these are still too expensive for developing countries. Electronic fetal monitoring equipment can cost over $2,000!
Problem Statement
Currently, many developing communities operate a simple pinard horn as a cheaper, albeit much less accurate, alternative. Not only is it hard to find the correct location of the baby, the natural fluids flowing within a pregnant mother’s body make it difficult to locate and hear the fetal heartbeat. Furthermore, calculating a heart rate using just a human ear and a clock can easily be misinterpreted and different people will get different results. Therefore, even though the pinard horn is more affordable, it is also much more prone to human error than more expensive and advanced fetal monitoring equipment.
Our Solution
Given the need for a low-cost and accurate system to measure fetal heart rates, we have identified a potential solution. Since the pinard horn is already widely used in third world countries and inexpensive to produce, we have decided, instead of prototyping a completely new product from scratch, to modify and improve upon the current model to fit those requirements. An added bonus is that midwives, who might be resistant to change, will not have to learn a new system.
Our original plan was to use an Arduino to program which of several multi-colored LED bulbs to light up depending on the heartbeat. For example, a red light signifies no heart rate is recognized and a green categorizes the heart rate to exist within a healthy range. We plan on finding an API to eliminate white noise from the audio input, and then identifying each individual heartbeat through data pattern recognition. Next, the program will calculate the heart rate and signal the correct light bulb to turn on.
After running into multiple problems with the microphone not being able to detect the sound of a heartbeat well, we teamed up with a couple Electrical Engineering students to help improve with our prototype design. We switched to using a Raspberry Pi in which the lightbulbs represent the range of the fetus' BPM.
Target Community
Undeveloped communities in Malwai that simply can't afford ultrasounds or other costly tools
by UNICEF
Research
Why is it important to monitor the fetal heart rate?
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In general, to monitor the health of the baby by seeing if the heart rate is within a normal range.
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Early detection of problems in order to alert medical advisors before it’s too late
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During labor, fetal heart rate accelerations and decelerations are also typically measured during labor.
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Often used for high-risk pregnancies, common amongst women with conditions such as elevated blood pressure, diabetes, and problematic fetal growth
Design Matrix
The design matrix was updated to reflect a clarification of the design options that the team considered. Even though the modified pinard horn and the modified pinard horn with a stethoscope were tied, the deciding factor was that people in developing countries still have limited access to smartphones and will likely prefer a modified pinard horn without a smartphone app. This is an important factor to consider because there is a very successful modified pinard horn project being undertaken by Winsenga. We may be able to learn from Winsenga's project while at the same time we can help a fill a gap for the poorest people in developing countries that don't have access to smartphones.
Process
MATERIALS
1x Microphone sound sensor
1x Arduino Uno
1x Microphone sound sensor
6x Male to male jumper wires
1x Battery
1x 220 Ohm resistor
1x LED light
Prototype 1
We have the LED, resistor, and the microphone sensor plugged into the breadboard, with jumper wires connecting the breadboard to the arduino. We used a battery to power the micro-controller and LED.
In the Arduino IDE, we wrote a simple program that we flash programmed onto the Arduino. It continuously reads from pin 7 on the Arduino. If the input value passes a certain threshold (which we can physically set on the microphone sensor), we will write to the pin 13, which is connected to the LED light through the breadboard and a jumper cable, turning it on.
In the video, we run a simulation of a continuously beating heartbeat. The LED in our project lights every time the microphone senses a sound past a certain threshold, it lights up. This is just an early step in our project. From here, we plan on writing another program to count and calculate the heart rate from the constant heart beats. We want to turn on a different colored LED based upon whether the heart rate is within a healthy range, too fast, or too slow.
CHALLENGES
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Settings for the sensitivity of the microphone sensor is difficult to determine. It is either too sensitive (in which the light will consistently be on) or not sensitive enough (in which the light does not turn on even when we make loud noises nearby). Since we need to use a micro-screwdriver to physically turn the dial to set the sensitivity, it is very difficult to be precise.
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We are unsure how to go about filtering out the extra noise in the abdomen. Professor Schwartz suggested a Fourier transform but we still have a lot to learn on this subject.
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We are working with a few engineering students and Professor Mastoridis to learn more about hardware for the project, choosing a new microphone, and filtering out important sound frequencies. We are thankful for their help but so far it has proved difficult to coordinate such a l
FAILURES
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We need to purchase a new microphone that detects various sound waves rather than just the existence or absence of sound.
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We didn't make much progress for a week because we couldn't figure out how to set up the proof of concept the same way that we previously had made it work. This has now been solved!
Prototype 2
Pinard horn attached to circuit board
We split up each LED bulb by a set range of BPMs
CHALLENGES
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Chose a highly technical approach where we had limited time/ knowledge to make it work or to try other approaches
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Was not familiar with Arduino coding choosing the right microphone
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Coordinating a large group with different areas of knowledge.
FAILURES
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Can’t hear an actual heartbeat
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Could’ve purchased more materials to test the project multiple ways with the same tech
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Didn’t define roles clearly – unclear communication
Ideas for Future
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Experiment with different types of microphones and placement
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Try stethoscope instead of pinard horn
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Try horns made of different materials and compare results
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Potentially set up the device more inexpensively and simply with circuit board
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Could potentially use solar electricity?
Project Outlook
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Everyone will be in school still or at jobs
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We are close to proof of concept so someone could continue
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WinSenga has been successful with a similar project.
Our Team
