Pulse Oximeter is ON, but does not give a reading
Cold hands and fingers are usually the issue when a pulse ox can’t provide a measurement.
Cold hands and fingers mean that the blood flow and circulation to your hand is reduced and may cause problem for the oximeter to detect a good pulse signal. When this happens, a pulse oximeter may take several minutes to return a reading and sometimes the reading may be inaccurate.
Under this situation, try to warm up your hands prior to taking a measurement. One good way is to massage your hands by rubbing them gently against each other. Doing some hand exercise would also increase blood circulation.