Why does the pulse oximeter not read my dad's recording properly?

Hi,

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The oximeter works well when the flow rate in the periphery is good. In normal people, it records the pulse and their oxygen saturation will be good. But in some people, when the flow to the fingers and toes is not good, it will not work well. It is common in chronic smokers and old patients where their vessels seem to be contracted. In these people, the pulse rate seems to be low and high and it will show a false reading. This is the reason for their hands and feet to be cold. I suggest you apply an oximeter to the loose skin of the ear lobule which means the hanging skin of the ear. Probably, the oximeter will show a good reading.