*4.4.4 Monitoring pulse oximetry*

Blood oxygen (SpO2) is the most often monitored parameter in patients with COPD. In general, COPD patients have a blood oxygen level that is lower than normal, but is maintained and the patient becomes accustomed. During exacerbation the level will fall, and a threshold may be set to generate an alert. **Figure 16** [45] shows SpO2 measurements for a typical COPD patient, the vertical dotted lines indicate clinical events. SpO2 is seen to fall at these times. However SpO2 also falls at other times, which would generate false alerts. Improved algorithms are required to improve accuracy.
