P145 NOCTURNAL OXYGEN DESATURATION IS COMMON IN INTERSTITIAL LUNG DISEASE AND OCCURS IN PATIENTS WITHOUT RESTING OR EXERCISE-INDUCED HYPOXIA

TJ Corte, SJ Wort, S Talbot, AU Wells. Royal Brompton Hospital, London, UK

In patients with interstitial lung disease (ILD), nocturnal oxygen desaturation is associated with poorer quality of life and may contribute to long-term vascular stress. Nocturnal desaturation is thought to be common in ILD patients, with previous studies reporting its prevalence at 50–88%.

Aim: To determine the prevalence of nocturnal desaturation in ILD patients and in the subgroup of patients without resting or exercise-induced hypoxia.

Methods: We reviewed all ILD patients (n  =  176, mean age 57.8 ± 13 years, 97 male) who had undergone overnight oximetry during 2005–8. All patients had pulmonary function and resting oxygen saturation (SpO₂), and 125 had 6-minute walk testing (6MWT). Significant nocturnal desaturation was considered as spending ⩾10% of sleep with SpO₂ ⩽90%. We determine the prevalence of nocturnal desaturation and its frequency in those without resting or exercise hypoxia.

Results: On overnight oximetry, 128 (73%) patients had oxygen desaturation to ⩽90% at any stage of the night. However, 73 (42%) had significant nocturnal desaturation (⩾10% of sleep with SpO₂ ⩽90%). Mean minimum SpO₂ was 84.0 ± 8.6% and fall in SpO₂ was 11.4 ± 8.4%. Patients spent an average of 18.1 ± 26.9% of the night below 90%. On 6MWT, mean end SpO₂ was 87.9 ± 7.5% and 6MWT distance was 325.4 ± 124.8 m. Sixty-two (50%) had oxygen desaturation to ⩽88% during 6MWT. Patients had a mean body mass index of 28.4 ± 6.7 kg/m²; TLco% 37.3 ± 16.6%; FVC% 66.3 ± 23.4% and SpO₂ 95.4 ± 2.5%. As demonstrated in the table, nocturnal desaturation was present in 49 of 149 (33%) patients without resting hypoxia and in 37 of 63 (59%) patients without desaturation on 6MWT.

Conclusion: Nocturnal desaturation is …