title: Hypoxic events and concomitant factors in preterm infants on non-invasive ventilation.
abstract: Automated control of inspired oxygen for newborn infants is an emerging technology, currently limited by reliance on a single input signal (oxygen saturation, SpO2). This is while other signals that may herald the onset of hypoxic events or identify spurious hypoxia are not usually utilised. We wished to assess the frequency of apnoea, loss of circuit pressure and/or motion artefact in proximity to hypoxic events in preterm infants on non-invasive ventilation. Hypoxic events (SpO2< 80 %) were identified using a previously acquired dataset obtained from preterm infants receiving non-invasive ventilation. Events with concomitant apnoea, loss of circuit pressure or oximetry motion artefact were annotated, and the frequency of each of these factors was determined. The effect of duration and timing of apnoea on the characteristics of the associated hypoxic events was studied. Among 1224 hypoxic events, 555 (45 %) were accompanied by apnoea, 31 (2.5 %) by loss of circuit pressure and 696 (57 %) by motion artefact, while for 224 (18 %) there were no concomitant factors identified. Respiratory pauses of longer duration (>15 s) preceding hypoxic events, were associated with a relatively slow decline in SpO2and more prolonged hypoxia compared to shorter pauses. Hypoxic events are frequently accompanied by respiratory pauses and/or motion artefact. Real-time monitoring and input of respiratory waveform may thus improve the function of automated oxygen controllers, allowing pre-emptive responses to respiratory pauses. Furthermore, use of motion-resistant oximeters and plethysmographic waveform assessment procedures will help to optimise feedback control of inspired oxygen delivery.
authors.affiliation: School of Engineering and ICT, University of Tasmania, Hobart, TAS, Australia. omid.sadeghi@utas.edu.au.
authors.forename: Omid Sadeghi
authors.identifier: http://orcid.org/0000-0002-7238-6235
authors.initials: OS
authors.lastname: Fathabadi
authors.affiliation: School of Engineering and ICT, University of Tasmania, Hobart, TAS, Australia.
authors.forename: Timothy
authors.initials: T
authors.lastname: Gale
authors.affiliation: Department of Paediatrics, Royal Hobart Hospital, Hobart, TAS, Australia.|Murdoch Children's Research Institute, Melbourne, VIC, Australia.
authors.forename: Kevin
authors.initials: K
authors.lastname: Wheeler
authors.affiliation: Department of Paediatrics, Royal Hobart Hospital, Hobart, TAS, Australia.
authors.forename: Gemma
authors.initials: G
authors.lastname: Plottier
authors.affiliation: Murdoch Children's Research Institute, Melbourne, VIC, Australia.|Newborn Research, The Royal Women's Hospital, Melbourne, VIC, Australia.|Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, VIC, Australia.
authors.forename: Louise S
authors.initials: LS
authors.lastname: Owen
authors.affiliation: School of Engineering and ICT, University of Tasmania, Hobart, TAS, Australia.
authors.forename: J C
authors.initials: JC
authors.lastname: Olivier
authors.affiliation: Department of Paediatrics, Royal Hobart Hospital, Hobart, TAS, Australia.|Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Dargaville
mesh_terms: D000465:Algorithms; D001049:Apnea; D016477:Artifacts; D003196:Computer Graphics; D045422:Continuous Positive Airway Pressure; D006801:Humans; D000860:Hypoxia; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000628:therapy; D009038:Motion; D063087:Noninvasive Ventilation / Q000295:instrumentation* / Q000379:methods; D010092:Oximetry / Q000295:instrumentation* / Q000379:methods; D010100:Oxygen; D012119:Respiration; D012815:Signal Processing, Computer-Assisted; D014584:User-Computer Interface
chemical_list: D010100:Oxygen
keywords: Apnoea; Automated oxygen control; Continuous positive airway pressure; Motion artefact; Preterm infants; Pulse oximetry