"COLIN LAMB" wrote in message
hlink.net...
Question - will the reading of the pulse oximeter discriminate against
carbon monoxide?

In other words, does the use of a pulse oximeter reduce the need of a
carbon
monoxide detector? If carbon monoxide replaces oxygen, then the % of
oxygen
would decrease and the oximeter would drop substantially when carbon
monoxide is present? Right?

Colin N12HS


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Pulse oximetry cannot distinguish between different forms of haemoglobin.
Carbo-xyhaemoglobin (haemoglobin combined with carbon monoxide) is
registered as 90% oxygenated haemoglobin and 10% desaturated haemoglobin -
therefore the oximeter will overestimate the saturation. The presence of
methaemoglobin will prevent the oximeter working accurately and the readings
will tend towards 85%, regardless of the true saturation.

So the answer to your question is - you still need a CO monitor if there's
an engine about.

Ian