Polysomnography helps adjust NIV settings: study


By Michael Woodhead

26 Mar 2019

People at risk of respiratory failure who require non-invasive ventilation fare better if their ventilator settings are titrated with polysomnography rather than standard daytime assessment, a study at an Australian sleep centre has shown.

Patients had less frequent ventilator asynchrony events and better adherence if they had polysomnography titration of ventilator settings, according to a study carried out in 60 patients being started on NIV at the Department of Respiratory and Sleep Medicine, Austin Health, Victoria.

In the study, which involved treatment-naïve individuals with neuromuscular disorders and respiratory muscle weakness, patients were randomised to either polysomnography titration of NIV or a control group of daytime titration.

At 10 weeks, the primary outcome of patient-ventilator asynchrony events was significantly less frequent in the polysomnography group compared to the control group (25.7 vs 41.0/hour). However there was no difference in the other primary outcome of arousals (11.4 vs 14.6/hour).

There were no differences in secondary outcomes of nocturnal gas exchange and overall measures of health-related quality of life. Somnolence and sleep quality improved in both groups to a similar degree.

While overall adherence was not significantly different for polysomnography and control groups, there was an increase seen of 95 minutes per day in patients with poor early adherence (<4 hours/day) compared to a 23 minute decrease in the control group.

The researchers, led by Dr Liam Hannan and Dr Mark Howard at Austin Health, said their study had shown that polysomnography was “an effective and clinically feasible titration method that is associated with lower levels of asynchrony.”

“The influence of polysomnographic titration on synchronisation appears to be mediated primarily through a reduction in ineffective efforts; with this form of PVA previously noted to predominate,” they noted.

They postulated that the short trial duration, stable disease and low patient numbers may have meant the study was not powered to detect differences in sleep events.

The increase in adherence of 95 minutes daily was likely to be of clinical importance if it could move people over the threshold of 4 hours use per day deemed significant for improving symptoms and PaCO2, they said

Shifting individuals above this threshold not only suggests an important clinical effect of polysomnographic titration, but also an easily identifiable cohort of users in which to apply it. Cost-effective methods of optimising adherence to NIV will become increasingly important if the indications for this therapy are broadened, particularly in health settings where prolonged inpatient evaluation and acclimatisation is expensive or unavailable.

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