TeleHealth Hardware

The US$10 TeleHealth Module

• This low cost, multifunction peripheral will provide a means through which the XO can relay valuable medical diagnostic data from the field to doctors many kilometers away.
• Good documentation needed, possibly via svg/javascript animations.
• It will compose of a three lead EKG providing valuable information about the heart's electrical status, enabling diagnosis of congenital defects and various arrhythmias.
• It will also contain a multipurpose NIR diagnosis tool whose primary function is that of a pulse oximeter, providing information about the oxygen saturation of the blood.
  • See nirdiagnositics.com for other NIR functions
• The long, time consuming parts
  • Getting approval from governmental and medical organizations.
  • Providing an intuitive interface and a pictograph manual.
  • Drivers, integration with Measure, and construction of a usable TeleHealth Database.

3 Electrode EKG

• How to do it
  • The first part is the actual hardware part. A circuit, possibly USB powered, using op-amps, would amplify the signal received by the sensor array(of three to twelve electrodes in contact with the skin, in proximity to the heart), to a voltage usable by an ADC. Hospital telemetry units typically use five-lead arrays and derive the standard 12-lead EKG. For diagnostics, the ability to produce a twelve-lead EKG would be infinitely preferable because this is what doctors are trained to read. There should also be at-the-point-of-need instructions for where to place each lead.
  • The second part is the safety part, due to the proximity to the heart, strict regulation of leakage current is needed.
  • The third part is adapt Measure to increase functionality as a Telemedicine platform.

• Implementation
  • Multiple Op-Amps pick up, amplify, and filter electrical impulses picked up by near-heart electrodes.
    • Older EKGs used suction based reusable electrodes, an adaption of these may be best suited for the third world where replacements are scarce.
  • DyD/DyDisMe has schematics for an EKG using AD620A style op-amps.
    • 4.1044-7.3 usd
  • Ram Dhurjaty, a medical device professional who has had substantial experience with EKG amplifiers, has pointed suggested that there are better amplifiers than the AD620.
  • Dirakx(Rafael Ortiz) is currently in the prototyping phase of an EKG, to incorporate into the THM, there is now a working protoype, tested with a conventional scope, not tested yet with measure, it needs a GUI for interpreting the EKG data, and also checking for international health regulations and also investigate the overall cost of the proyect.

NIR Diagnosis Aid

• Based on the principles of the differences in absorption of oxygenated and non oxygenated hemoglobin
• 800-1000nm light from LEDs are often used in NIR tools
  • The most cited frequencies for IR Pulse Oximetery include 805nm, 910nm, and 940nm.
  • 940nm IR LED; 12.2c per unit
• Red light is generated from similar LEDs.
  • 10-20c per unit
• Light is picked up by photodiodes, converted to current.
• This current is amplified and converted to voltage by a MAX4006 or equivalent chip
  • 1.275 usd

Stethoscope

The stethoscope was invented in 1816 by Rene Laennec to avoid having to place his ear to a woman's chest to listen to her heart. Improvements were made in terms of convenience, by adding tubing instead of using a solid wooden trumpet design, but the stethoscope has not changed much since it was invented.

Today, electronic stethoscopes are becoming more common, gradually supplanting the conventional stethoscope. The electronic stethoscope provides amplification and filtering, and facilitates connection to external devices for recording and transmitting heart and lung sounds. This is convenient for record-keeping of auscultation findings, and for remote auscultation of heart sounds and lung sounds.

An example of a modern electronic stethoscope with such a connection is the Thinklabs ds32a stethoscope. This device can connect to laptop computers, as well as iPods and other recorders. By connecting a stethoscope to a laptop or notebook computer, and transmitting sounds, clinics can be set up im remote places for examination of children by a pediatric cardiologist to differentiate between innocent and pathological murmurs.

Here's an example of a electronic stethoscope that can be built with any stethoscope head, a piece of tubing and a lapel microphone. This particular version uses a battery, but a similar device should be able to draw power from a USB port. The signal is fairly clean, you can hear breath sounds and about halfway through you can hear a playmate giggle in the background, but the signal does require substantial amplification.

Suggestion: Too much "signal" is probably being lost due to the stethescope head itself. Another bit of research being done involves using a "cheap" mp3 recorder, pressed directly to the patients chest, to record breath and heart sounds. What about using just small housing around the lapel mike, pressed against the chest? (or indeed, the XO itself?)

ADC/DAC

• C8051F321 or equivalent chip
  • A/D 5x10b minimum
  • This specific chip provides A/D 13x10b
• Alternatively a USB micro-controller may communicate with dedicated ADC/DAC chips via PWM, to lower cost.
• Honza Kovar(Jan), from the Czech republic, has acquired development board for the C8051F321 MCU, and will assist with programming and development.

THDB

• TeleHealth Database

Contributors

• Ian Daniher
• Ram Dhurjaty (Simple concept suggested elsewhere)
• Rafael Ortiz
• Steve Burns
• Seth Woodworth (isforinsects)

Resources

• http://www.olpcnews.com/use_cases/community/medical_application_community.html
• http://openeeg.sourceforge.net/doc/links-biopsy.html
• http://library.med.utah.edu/kw/ecg/
• http://www.uneca.org/itca/healthport/discussions.htm
• stethoscopeThinklabs electronic stethoscope for connection to laptop computers.
• World Stethoscope A universal appliance to get real-time environment data into Etoys. The original World Stethoscope converts sensor data into sound which is read via a computer's microphone input (hence the name). We intend to use the World Stethoscope's Etoy user interface with the OLPC XO's AD-converter directly.

See also

• Category:Health
• Vision screening