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Design of a System that Transfers Ventilator Information to the Internet

Design of a System that Transfers Ventilator Information to the Internet. Lauren Sims Advisor: Dr. Bill Walsh. Background. Mechanical neonatal respirators play an important role…. Ensuring adequate respiration in infants is difficult involuntary mechanism

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Design of a System that Transfers Ventilator Information to the Internet

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  1. Design of a System that Transfers Ventilator Informationto the Internet Lauren Sims Advisor: Dr. Bill Walsh

  2. Background Mechanical neonatal respirators play an important role…. • Ensuring adequate respiration in infants is difficult • involuntary mechanism • the tongue is proportionally larger than in an adult • trachea is very flexible (easy to kink) • lungs have proportionally less volume and compliance • large head/body ratio requires care to maximize airway • Ensuring adequate respiration is very important • primary cause of cardiac arrest is respiratory failure • risk of long term (i.e., brain) damage from abnormal breathing

  3. Typical Flow Time Waveform This Flow Time Waveform is from a full term infant. The lungs are essentially normal. The normal decelerating flow time waveform consists of the following: *Rapid rise to peak inspiratory flow with the initiation of inspiration. *Inspiratory flow decays rapidly to baseline and smoothly transitions to expiratory flow. The decay becomes exponential as it approaches the baseline. *Rapid rise to peak expiratory flow. *Exponential decay of expiratory flow back to baseline.

  4. Background .... but careful monitoring of respiration is not efficient ! • Respirator has a built in monitoring system, but... • screen is local to respirator • controls are local to respirator • requires dedicated personnel presence at all times • Respirator also has the capability for remote monitoring • built-in data collection via internal microprocessor • built-in RS-232C data transmission capability • built-in software command set for microprocessor data retrieval • Remote monitoring capability is currently unused

  5. Siemens SV300 Servo Ventilator

  6. My Project Investigate the possibility of moving monitoring function to the web • Is it possible to get at performance data via the serial port? • Is it possible to post the data to a web page on a server? • Would web enabled monitoring bring better care or lower costs?

  7. Results Good performance data is available on the SV300 via an RS-232 interface..... • Curve • Trend • Alarm • Breath • Settings • Technical (battery state, etc.) .... but RS-232 is difficult and code is computer Operating System dependent. ('ServoVentilator 300/300A ReferenceManual', Siemens-Elema AB, 1997).

  8. Channels 00-99: Basic Airway Flow 5V/l/s Insp. Tidal Volume 5V/L Airway Pressure 50mV/cm H2O Exp. Tidal Volume 5V/L O2 Concentration 50mV/% Barometric Press. 4.883 V/Bar Aux Code 4.883 mV/bit Pause Pressure 50mV/cm H2O Resp. Rate calc 50mV/breaths/minute Peak Pressure 50mv/cm H2O Exp. Minute vol. 0.2V/l/min Airway pressure 50mV/cm H2O CI Battery Voltage 1mV/mV End exp. Pressure 100mV/cm H2O Channels 100-199: Extended Airway Flow and Pressure AUX Channels 1-8 CI battery voltage Measured & CMV frequency Exp/Insp Tidal Volume and minute volume Peak Pressure O2 concentration Barometric & Gas supply pres. (air, O2) Inspiration and pause times Alarm Reset/2 min off & option SIMV frequency PEEP, set; Pressure limits, set Exp. Minute vol; upper/lower alarm limit Ventilation mode, Set Valve slots 1-3, binary codes Alarms: apnea, power failure, mode switch error, Mains failure, overrange, CI internal communication error, O2 concentration levels, gas supply, battery, etc. Some Parameters and Scaling Factors

  9. Results • An example RS-232 communications program for DOS is available. • printed in the ventilator technical manual • around 1200 lines of 'C' code • uses the Greenleaf CommLib version 3.2 'C' libraries for DOS ($400) • has some 'C' functions that are peculiar to DOS compiler ($400) (e.g., delay(), kbhit(), getch(), itoa(), etc.) • I am trying to port this code to Linux (with help). • linux is free • linux has a C compiler (also free) • I have access to a free serial library for Linux (serial.c) • linux has equivalent function calls (i.e., usleep() instead of delay()) • linux has a built-in web server

  10. Results • I have obtained a unix serial library (corcordt@cs.purdue.edu) • I have typed in all of the example 'C' code from the manual (see: <http://www.virtualdave.com/~lauren/bme272>) • I am working on porting the example code to unix (linux); i.e., replacing all the DOS Greenleaf library calls in the example code (e.g., asigetc(), aisputc(), etc.) with unix serial calls (e.g. IO_Read(), IO_Write, etc.) with Prof. J. M. Fitzpatrick. • Only three functions left to port over (asigets_timed(), asigetc_timed() and isrxempty()) which are all similar • Should have a RS-232 communication executable by Wednesday, April 4

  11. Resources Needed • I need access to an SV300 ventilator to test/debug (weekend?) • I need a laptop that I can install linux on for testing/debugging

  12. Future Work • Once communications are established and access to the data from the respirator is obtained, it shouldn't be too hard to pipe the data to a web page and serve it. • Finalize poster presentation for April 11th.

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