Characteristics of the nocturnal desaturation waveform pattern of SpO 2 in COPD patients: an observational study

Nocturnal desaturation is common in patients with chronic obstructive pulmonary disease (COPD) and impacts disease exacerbation and prognosis. In our previous study, we developed a diagnostic algorithm to classify nocturnal desaturation from SpO waveform patterns based on data from patients receiving home oxygen therapy. In this study, we aimed to investigate nocturnal desaturation in patients with COPD based on SpO waveform patterns and the associations between the waveforms and clinical data. We investigated patients diagnosed with COPD and measured SpO and nasal airflow with a type 4 portable long-term recordable pulse oximeter. Then, we classified the SpO waveforms with the algorithm and compared the clinical data. One hundred fifty-three patients (136 male and 17 female) were analysed. One hundred twenty-eight of the 153 (83.7%) patients had nocturnal desaturation, with an intermittent pattern (70.6%), sustained pattern (13.1%) and periodic pattern (68.0%). Intriguingly, desaturation with an intermittent pattern was associated with the apnoea-hypopnea index obtained with the portable monitor, and desaturation with a sustained pattern was associated with the cumulative percentage of time at a SpO below 90%. We found that nocturnal desaturation was frequently observed in patients with COPD and could be classified into 3 types of waveform patterns.