Long-term oxygen therapy improves survival in patients with severe hypoxia. However, some patients despite this oxygen, experience episodes of low oxygen levels (intermittent hypoxia) especially during sleep which may be harmful. In order to overcome this, the investigators have designed an auto-titrating oxygen system (called intelligent oxygen therapy) which automatically adjusts oxygen flow rates to maintain oxygen levels in patients already on oxygen. This study will investigate whether the intelligent oxygen therapy system can prevent intermittent hypoxia during sleep in patients already on long-term oxygen.
Long-term oxygen therapy (LTOT) improves survival in patients with chronic obstructive pulmonary disease (COPD) and severe persistent hypoxia. LTOT is prescribed at a fixed-flow rate with the aim of maintaining a partial pressure of oxygen greater than or equal to 8 kilopascals (kPa). However, a number of studies have demonstrated that patients on home LTOT experience episodes of intermittent hypoxia during rest, activities and especially sleep. Simply increasing the oxygen flow rate at night can relieve this hypoxia but at the expense of hyperoxia with its detrimental effects of hypercapnia and respiratory acidosis. Therefore, a more targeted approach is needed to oxygen delivery. The investigators have devised an auto-titrating oxygen system (intelligent oxygen therapy \[iO2Ts\]) which delivers variable flow oxygen to maintain a pre-set specific oxygen saturation ( SpO2) target. The system can avoid the dual hazards of hypoxia and hyperoxia and potentially optimise LTOT. This study will be investigating whether the iO2Ts can reduce intermittent hypoxia during sleep compared to usual fixed flow oxygen in patients on LTOT. Nineteen patients will be recruited to undergo two sleep studies each on two different nights; one on their usual LTOT flow rate and one of the iO2Ts. During both sleep studies, all participants will have full polysomnography, oxygen and transcutaneous carbon dioxide monitoring. The primary outcome will the percentage of time spent with SpO2 \< 90% during sleep.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
Royal Brompton and Harefield NHS Foundation Trust
London, United Kingdom
The percentage of time spent with SpO2 <90% during sleep (%)
The difference in percentage time spent at SpO2 less than 90% during sleeping usual LTOT and iO2T (measured as %)
Time frame: 10 hours in bed
The percentage of time spent with SpO2 >96% during sleep (%)
The percentage of time during sleep with an SpO2 value \>96% (measured as %)
Time frame: 10 hours in bed
The mean transcutaneous carbon dioxide level during sleep (measured in kPa)
Mean level of transcutaneous carbon dioxide level during sleep (measured in kPa)
Time frame: 10 hours in bed
The peak transcutaneous carbon dioxide level during sleep measures in kPa
The maximum level of transcutaneous carbon dioxide during sleep (measured in kPa)
Time frame: 10 hours in bed
The mean sleep SpO2
The mean level of SpO2 during sleep (measured in SpO2 %)
Time frame: 10 hours during sleep
Sleep quality as measured on a visual analogue scale (0 - 100mm).
The morning after the sleep study, participants will complete a visual analogue scale of their sleep quality. The visual analogue scale is on a A4 paper, it is a straight line of 100mm.
Time frame: 10 hours in bed
Total Sleep time
The total amount of time spent in sleep confirmed by polysomnography (measured in minutes)
Time frame: 10 hours during sleep
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SINGLE
Enrollment
6
Sleep efficiency
This is the total amount of time the patients actually slept divided by the total time they were in bed (measured as a percentage).
Time frame: 10 hours in bed