Background It is common for CF children in the UK to receive sleep-disrupting 4 hourly observations day and night throughout their hospital stays for intravenous antibiotics or exacerbations judging from parental and patient feedback. As oxygen desaturations occur mainly during REM sleep rather than NREM sleep, these desaturations could be missed by the intermittently performed “routine observations”. Our unit performs nocturnal oximetry studies on night 1 of admission for all CF patients admitted for intravenous antibiotics and discontinues them if oxygenation is normal and the patient improving.

Aims To determine whether day time physiology or lab work is predictive of nocturnal hypoxaemia.

Methods A retrospective comparison of nocturnal oximetry studies and daytime physiology plus HbA1c of all CF patients admitted for intravenous antibiotics between January and June 2013.

Results 54 CF patients were admitted, with 19/54 elective and 35/54 acutely. Table 1 summarises the clinical characteristics and nocturnal oximetry results of the patients. There was a weak positive correlation between Mean SpO2 and admission FEV1 (p = 0.0012, r² = 0.21) and admission FVC (p = 0.0024, r² = 0.18). Nocturnal oxygen was commenced in 4/54 children (7.4%) as their mean SpO2 was < 93%. All of them had an FVC < 60%, the only ones in the cohort. 3 of the children improved (FVC improved to 71%, 75% and 87% from 44%, 54% and 58% respectively), they were weaned off oxygen before discharge, with normal gas exchange on repeat nocturnal oximetry) and 1 died.

Conclusion Patients with an admission FVC of <60% warrant close monitoring for nocturnal hypoxaemia. In CF patients who are cardiovascularly stable, performing an oximetry study on first night of admission may be a less disruptive alternative to routine intermittent observations nightly for the whole duration of the admission.