{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T22:27:29Z","timestamp":1791930449302,"version":"4.3.4"},"reference-count":34,"publisher":"BMJ","issue":"1","license":[{"start":{"date-parts":[[2021,12,9]],"date-time":"2021-12-09T00:00:00Z","timestamp":1639008000000},"content-version":"unspecified","delay-in-days":8,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100010269","name":"Wellcome","doi-asserted-by":"publisher","award":["213486\/Z\/18\/Z"],"award-info":[{"award-number":["213486\/Z\/18\/Z"]}],"id":[{"id":"10.13039\/100010269","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open Resp Res"],"accepted":{"date-parts":[[2021,11,18]]},"published-print":{"date-parts":[[2021,12]]},"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Respiratory disorders, including apnoea, are common in preterm infants due to their immature respiratory control compared with term-born infants. However, our inability to accurately measure respiratory rate in hospitalised infants results in unreported episodes of apnoea and an incomplete picture of respiratory activity.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We develop, validate and use a novel algorithm to identify interbreath intervals (IBIs) and apnoeas in preterm infants. In 42 preterm infants (1600 hours of recordings), we assess IBIs from the chest electrical impedance pneumograph using an adaptive amplitude threshold for the detection of breaths. The algorithm is refined by comparing its accuracy with clinically observed breaths and pauses in breathing. We develop an automated classifier to differentiate periods of true apnoea from artefactually low amplitude signal. We assess the performance of this algorithm in the detection of morphine-induced respiratory depression. Finally, we use the algorithm to investigate whether retinopathy of prematurity (ROP) screening alters the IBI distribution.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Individual breaths were detected with a false-positive rate of 13% and a false-negative rate of 12%. The classifier identified true apnoeas with an accuracy of 93%. As expected, morphine caused a significant shift in the IBI distribution towards longer IBIs. Following ROP screening, there was a significant increase in pauses in breathing that lasted more than 10 s (t-statistic=1.82, p=0.023). This was not reflected by changes in the monitor-derived respiratory rate and no episodes of apnoea were recorded in the medical records.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>We show that our algorithm offers an improved method for the identification of IBIs and apnoeas in preterm infants. Following ROP screening, increased respiratory instability can occur even in the absence of clinically significant apnoeas. Accurate assessment of infant respiratory activity is essential to inform clinical practice.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjresp-2021-001042","type":"journal-article","created":{"date-parts":[[2021,12,10]],"date-time":"2021-12-10T11:31:47Z","timestamp":1639135907000},"page":"e001042","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":18,"title":["New method to measure interbreath intervals in infants for the assessment of apnoea and respiration"],"prefix":"10.1136","volume":"8","author":[{"given":"Tricia","family":"Adjei","sequence":"first","affiliation":[{"name":"Department of Paediatrics, University of Oxford, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ryan","family":"Purdy","sequence":"additional","affiliation":[{"name":"Department of Paediatrics, University of Oxford, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jo\u00e3o","family":"Jorge","sequence":"additional","affiliation":[{"name":"Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eleri","family":"Adams","sequence":"additional","affiliation":[{"name":"Newborn Care Unit, Oxford University Hospitals NHS Foundation Trust, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Miranda","family":"Buckle","sequence":"additional","affiliation":[{"name":"Department of Paediatrics, University of Oxford, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ria","family":"Evans Fry","sequence":"additional","affiliation":[{"name":"Department of Paediatrics, University of Oxford, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gabrielle","family":"Green","sequence":"additional","affiliation":[{"name":"Department of Paediatrics, University of Oxford, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chetan","family":"Patel","sequence":"additional","affiliation":[{"name":"Department of Ophthalmology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Richard","family":"Rogers","sequence":"additional","affiliation":[{"name":"Department of Anaesthetics, Oxford University Hospitals NHS Foundation Trust, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rebeccah","family":"Slater","sequence":"additional","affiliation":[{"name":"Department of Paediatrics, University of Oxford, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lionel","family":"Tarassenko","sequence":"additional","affiliation":[{"name":"Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mauricio","family":"Villarroel","sequence":"additional","affiliation":[{"name":"Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7981-0836","authenticated-orcid":false,"given":"Caroline","family":"Hartley","sequence":"additional","affiliation":[{"name":"Department of Paediatrics, University of Oxford, Oxford, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2021,12,10]]},"reference":[{"key":"2025083109370062000_8.1.e001042.1","doi-asserted-by":"publisher","DOI":"10.1159\/000084876"},{"key":"2025083109370062000_8.1.e001042.2","doi-asserted-by":"crossref","first-page":"E388","DOI":"10.1111\/jpc.12247","article-title":"Current definitions for neonatal apnoea: are they evidence based?","volume":"49","author":"Elder","year":"2013","journal-title":"J Paediatr Child Health"},{"key":"2025083109370062000_8.1.e001042.3","doi-asserted-by":"crossref","first-page":"S47","DOI":"10.1542\/peds.2005-0620H","article-title":"Summary proceedings from the apnea-of-prematurity group","volume":"117","author":"Finer","year":"2006","journal-title":"Pediatrics"},{"key":"2025083109370062000_8.1.e001042.4","doi-asserted-by":"publisher","DOI":"10.1111\/j.1442-200X.2003.01803.x"},{"key":"2025083109370062000_8.1.e001042.5","doi-asserted-by":"publisher","DOI":"10.1038\/sj.jp.7211182"},{"key":"2025083109370062000_8.1.e001042.6","doi-asserted-by":"publisher","DOI":"10.1159\/000097446"},{"key":"2025083109370062000_8.1.e001042.7","doi-asserted-by":"publisher","DOI":"10.1183\/20734735.000716"},{"key":"2025083109370062000_8.1.e001042.8","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1038\/pr.2016.43","article-title":"Clinical associations of immature breathing in preterm infants: part 1-central apnea","volume":"80","author":"Fairchild","year":"2016","journal-title":"Pediatr Res"},{"key":"2025083109370062000_8.1.e001042.9","doi-asserted-by":"publisher","DOI":"10.1183\/23120541.00330-2019"},{"key":"2025083109370062000_8.1.e001042.10","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa054065"},{"key":"2025083109370062000_8.1.e001042.11","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(18)31813-0"},{"key":"2025083109370062000_8.1.e001042.12","doi-asserted-by":"publisher","DOI":"10.1097\/ANC.0b013e318225a332"},{"key":"2025083109370062000_8.1.e001042.13","doi-asserted-by":"publisher","DOI":"10.1088\/0967-3334\/33\/1\/1"},{"key":"2025083109370062000_8.1.e001042.14","first-page":"157","article-title":"Accurate automated apnea analysis in preterm infants","volume":"31","author":"Vergales","year":"2014","journal-title":"Am J Perinatol"},{"key":"2025083109370062000_8.1.e001042.15","doi-asserted-by":"crossref","first-page":"2550","DOI":"10.1111\/apa.15888","article-title":"Limitations of thoracic impedance monitoring for central apnoea detection in preterm infants","volume":"110","author":"Lim","year":"2021","journal-title":"Acta Paediatr"},{"key":"2025083109370062000_8.1.e001042.16","unstructured":"Philips K . IntelliVue patient monitor [online], 2019. Available: https:\/\/www.fda.gov\/media\/137229\/download [Accessed 8 Oct 2020]."},{"key":"2025083109370062000_8.1.e001042.17","unstructured":"Draeger . Infinity acute care system: instructions for use [online], 2017. Available: https:\/\/www.draeger.com\/Products\/Content\/iacs-vg7-monitoring-applications-ifu-ms34093-en.pdf [Accessed 8 Oct 2020]."},{"key":"2025083109370062000_8.1.e001042.18","unstructured":"Welch Allyn 1500 patient monitor [online], 2013. Available: https:\/\/www.welchallyn.com\/content\/dam\/welchallyn\/documents\/upload-docs\/Training-and-Use\/User-Manual\/Welch-Allyn-1500-Patient-Monitor-Software-version-1.4.X_User-Manual.pdf [Accessed 8 Oct 2020]."},{"key":"2025083109370062000_8.1.e001042.19","unstructured":"Jorge J . Non-contact monitoring of respiration in the neonatal intensive care unit [PhD Thesis]. University of Oxford, 2018."},{"key":"2025083109370062000_8.1.e001042.20","doi-asserted-by":"crossref","first-page":"1","DOI":"10.3389\/fped.2020.00570","article-title":"Predicting apnoeic events in preterm infants","volume":"8","author":"Lim","year":"2020","journal-title":"Front Pediatr"},{"key":"2025083109370062000_8.1.e001042.21","doi-asserted-by":"crossref","first-page":"2335","DOI":"10.1109\/JBHI.2019.2898273","article-title":"Assessment of signal processing methods for measuring the respiratory rate in the neonatal intensive care unit","volume":"23","author":"Jorge","year":"2019","journal-title":"IEEE J Biomed Health Inform"},{"key":"2025083109370062000_8.1.e001042.22","doi-asserted-by":"crossref","unstructured":"Zong W , Moody GB , Jiang D . A robust open-source algorithm to detect onset and duration of QRS complexes. Computers Cardiol 2003:737\u201340.","DOI":"10.1109\/CIC.2003.1291261"},{"key":"2025083109370062000_8.1.e001042.23","doi-asserted-by":"crossref","unstructured":"Zong W , Heldt T , Moody GB . An open-source algorithm to detect onset of arterial blood pressure pulses. Computer Cardiol 2003:259\u201362.","DOI":"10.1109\/CIC.2003.1291140"},{"key":"2025083109370062000_8.1.e001042.24","doi-asserted-by":"crossref","unstructured":"Karlen W , Ansermino JM , Dumont G . Adaptive pulse segmentation and artifact detection in photoplethysmography for mobile applications. in: Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS 2012:3131\u20134.","DOI":"10.1109\/EMBC.2012.6346628"},{"key":"2025083109370062000_8.1.e001042.25","doi-asserted-by":"publisher","DOI":"10.1016\/j.neuroimage.2014.01.060"},{"key":"2025083109370062000_8.1.e001042.26","unstructured":"National Institute for Health and Care Excellence . Specialist neonatal respiratory care for babies born preterm. NICE guideline NG124 2019."},{"key":"2025083109370062000_8.1.e001042.27","doi-asserted-by":"crossref","first-page":"41","DOI":"10.3233\/NPM-15814071","article-title":"Discontinuing caffeine in preterm infants at 33-35 weeks corrected gestational age: failure rate and predictive factors","volume":"8","author":"Haddad","year":"2015","journal-title":"J Neonatal Perinatal Med"},{"key":"2025083109370062000_8.1.e001042.28","doi-asserted-by":"publisher","DOI":"10.1136\/archdischild-2012-303369"},{"key":"2025083109370062000_8.1.e001042.29","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1002\/(SICI)1099-0496(199902)27:2<113::AID-PPUL7>3.0.CO;2-O","article-title":"Predischarge monitoring of preterm infants","volume":"27","author":"Razi","year":"1999","journal-title":"Pediatr Pulmonol"},{"key":"2025083109370062000_8.1.e001042.30","doi-asserted-by":"publisher","DOI":"10.1203\/01.PDR.0000064904.05313.D2"},{"key":"2025083109370062000_8.1.e001042.31","doi-asserted-by":"crossref","first-page":"210","DOI":"10.1038\/s41390-019-0527-0","article-title":"Continuous vital sign analysis for predicting and preventing neonatal diseases in the twenty-first century: big data to the forefront","volume":"87","author":"Kumar","year":"2020","journal-title":"Pediatr Res"},{"key":"2025083109370062000_8.1.e001042.32","doi-asserted-by":"crossref","first-page":"e133","DOI":"10.1016\/j.bja.2020.10.034","article-title":"Predicting severity of adverse cardiorespiratory effects of morphine in premature infants: a post hoc analysis of procedural pain in premature infants trial data","volume":"126","author":"Hartley","year":"2021","journal-title":"Br J Anaesth"},{"key":"2025083109370062000_8.1.e001042.33","doi-asserted-by":"publisher","DOI":"10.1159\/000079542"},{"key":"2025083109370062000_8.1.e001042.34","doi-asserted-by":"publisher","DOI":"10.1016\/j.jaapos.2009.04.008"}],"container-title":["BMJ Open Respiratory Research"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/bmjresp-2021-001042","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,8,31]],"date-time":"2025-08-31T16:37:13Z","timestamp":1756658233000},"score":1,"resource":{"primary":{"URL":"https:\/\/bmjopenrespres.bmj.com\/lookup\/doi\/10.1136\/bmjresp-2021-001042"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,12]]},"references-count":34,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2021,12,10]]},"published-print":{"date-parts":[[2021,12]]}},"alternative-id":["10.1136\/bmjresp-2021-001042"],"URL":"https:\/\/doi.org\/10.1136\/bmjresp-2021-001042","relation":{"has-preprint":[{"id-type":"doi","id":"10.1101\/2021.05.29.21258043","asserted-by":"object"}]},"ISSN":["2052-4439"],"issn-type":[{"value":"2052-4439","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,12]]}}}