Do patients on NIV change their NIV use on nights when they have oximetry

Introduction: Intermittent overnight oximetry is used to monitor the effectiveness of home NIV. Aim: The aim of this study was to determine if patients change their ventilator use on the night they have oximetry. Objectives: To compare NIV use when having oximetry to 7 days later. Methods: The Lumis ventilator comes with remote access for 3 months. Consecutive patients issued with a Lumis ventilator were identified who had oximetry within the first 3 months of issue. NIV Use on the night of oximetry was compared with 7 days later using paired t-tests. Results: 168 patients were issued a Lumis of which 25 (15%) had oximetry within 3 months. 16/25 (64%) received NIV for single aetiology respiratory failure (OHS 9, copd 3, skeletal 3, neuromuscular 2) and 9 (36%) for overlap (ohs/copd 6, ohs/skeletal 1, OHS/central apnoea/drugs 2).20 received bi-level ST mode, 8 dynamic modes e.g. IVAPS. 7 had oxygen. Oximetry results –median (range) were ODI 7.8 (0.3-51), Median SpO2 94 (84-99), time 92%, Time The mean use of NIV on oximetry was 380 (SD 206) vs 319 mins (232) 7 days later. As a group there was no stat difference between the two nights (mean 60 mins more on oximetry , 95%CI 43 less to 165 more, p=0.24). However in some cases large differences in use were seen in either direction- range 377 less to 647 more. This is clinically important when assessing adequacy of NIV. Conclusion: Oximetry is best interpreted with NIV compliance data as there can be large and and unpredictable differences in use between nights when oximetry is and is not used.