Variation in hypoxia and hypercapnia definition used between CF centres in the UK and Australasia (16 centres were unsure of the definitions)
| Hypoxia | Hypercapnia |
| Frequent desaturations <90% | Petco2 >6.7 kPa |
| Baseline Sao2 <93% | CO2 >6.7 kPa for >25% sleep study |
| Spo2 <90% for >10% sleep study | Tcco2 rise to 6.7 kPa or rise by 0.9 kPa during sleep |
| Spo2 <92% for >5% sleep study | CO2 >7 kPa |
CO2, carbon dioxide; Petco2, end tidal carbon dioxide pressure; Saco2, arterial oxygen saturations; Spco2, non-invasive oxygen saturations; Tcco2, transcutaneous carbon dioxide pressure.