pulse oximetry - medical electronics

[leoren_tm]

A battery−powered pulse−oximeter is to be designed for use in the operating theatre.
(a) Indicate how you would attempt to eliminate ambient light interference.
(b) Both the red and infra−red light−emitting diodes (LEDs) use to illuminate the patient’s finger are pulsed at a frequency close to 10 kHz. Describe, using circuit diagrams, the circuits required to achieve this. In order to conserve power, a low duty cycle should be used and the current drawn from the battery should be reduced to a minimum during the LED off period.
(c) During surgery, peripheral blood flow is often considerably reduced and hence the pulses recorded with the oximeter are of much lower amplitude. In an attempt to cope with this, approximately 60 cardiac synchronous waveforms are averaged. The electrocardiogram (ECG) is used to provide as the trigger for the averaging circuit.
i. Why is (or isn’t) the value of 60 a sensible choice for the number of pulses to be averaged?
ii. Describe, using block diagrams, the hardware system which you would use to produce the averaged pulse. Assume that the output from an ECG amplifier is available.


if someone has idea on these matter, pls help me...

thanks..

 

[sbajaj]

A battery−powered pulse−oximeter is to be designed for use in the operating theatre.
(a) Indicate how you would attempt to eliminate ambient light interference.
(b) Both the red and infra−red light−emitting diodes (LEDs) use to illuminate the patient’s finger are pulsed at a frequency close to 10 kHz. Describe, using circuit diagrams, the circuits required to achieve this. In order to conserve power, a low duty cycle should be used and the current drawn from the battery should be reduced to a minimum during the LED off period.
(c) During surgery, peripheral blood flow is often considerably reduced and hence the pulses recorded with the oximeter are of much lower amplitude. In an attempt to cope with this, approximately 60 cardiac synchronous waveforms are averaged. The electrocardiogram (ECG) is used to provide as the trigger for the averaging circuit.
i. Why is (or isn’t) the value of 60 a sensible choice for the number of pulses to be averaged?
ii. Describe, using block diagrams, the hardware system which you would use to produce the averaged pulse. Assume that the output from an ECG amplifier is available.


if someone has idea on these matter, pls help me...

thanks..

WELL I M ALSO INTERSTED IN THE SAME ANSWERS IF OU DID FIND THEM PLS FORWARD THEM TO ME TOO.. THANKS BUDDY
sbajaj@gawab.com

Added after 2 minutes:

well i would post whatever information i have gathered about the topic in a few hrs time... at work at the moment

 

[RegUser_2]

Take a look in the patent database. There are too many articles on the subject. The "low perfusion" types patented by Masimo use three wavelenghts adaptive estimator to compenstate for the patient motion artefacts.