Sleep and developmental outcome of the moderate to late preterm infant

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dc.contributor.advisorBoylan, Geraldine B.
dc.contributor.advisorMathieson, Sean
dc.contributor.advisorDempsey, Eugene M.
dc.contributor.authorRyan, Mary Anneen
dc.date.accessioned2024-05-29T07:26:58Z
dc.date.available2024-05-29T07:26:58Z
dc.date.issued2023en
dc.date.submitted2023
dc.description.abstractBackground Sleep is the primary activity during early brain development and an essential part of healthy cognitive, physical and psychosocial development. Electroencephalography (EEG) provides detailed information about brainwave activity during sleep which changes in different sleep states and advancing gestational age (GA). The moderate to late preterm (MLP) infant is defined as an infant born between 32-36 +6 weeks GA. MLP’s are under-researched in terms of developmental outcome. We hypothesise that: • The sleep architecture of healthy MLP infants at 36 weeks may differ according to birth GA, birth weight, sex, mode of feeding or location (cot/incubator) at time of monitoring. • The developmental outcome of healthy MLP infants may be different to that of a term control group at 4 months and 18 months PMA. Aims • To describe the sleep architecture of healthy MLP infants in the neonatal unit at 36 weeks and the frequency of sleep interruptions using continuous EEG monitoring with video. • To describe parameters for the main EEG feature of quiet sleep i.e. inter-burst intervals (IBI) of MLP group with a normal developmental outcome at 18 months • To compare neurodevelopmental outcome of the MLP infant group to that of a term control (TC) infant group at 4 months and 18 months. Methods MLP infants recruited in the neonatal unit had overnight continuous EEG monitoring (12 hours) with video at 36 weeks post menstrual age (PMA). Post-acquisition, sleep states and sleep interruptions were annotated and quantified based on visual analysis of EEG, behavioural observation and cardiorespiratory parameters. Using an inter-burst interval (IBI) detection algorithm five IBI features of QS were extracted from MLP infants with a normal developmental outcome at 18 months. Outcome of MLP infant group was compared to a healthy term control (TC) group based on scores achieved in the Griffiths lll mental development scales at 4 and 18 months PMA. In comparing outcome of MLP and TC infant groups, the Mann–Whitney U test was used for continuous variables and the Chi-squared test or Fisher’s exact test was used for categorical variables. A p-value <0.05 is considered to be statistically significant. Cohens d (the standardized mean difference between the MLP and TC groups) was used as the measure of effect size. Results Ninety-eight infants had overnight EEG’s included in this study. In the neonatal unit 23.3% of sleep cycles were interrupted primarily for feeding. The total overnight sleep time (TST) was 7.09(6.61-7.76) hrs including 4.58(3.69-5.09) hrs in active sleep (AS), 2.02(1.76-2.36) hrs in quiet sleep (QS) and 0.65(0.48-0.89) hrs in indeterminate sleep (IS). The total duration of AS was significantly lower in infants born at lower GA (p= 0.007) whilst the duration of individual QS periods was significantly higher (p=0.001).Sixty infants had a normal outcome at 18 months and were included in the QS analysis study using the IBI detection algorithm. Normative data for five IBI features was extracted from QS. All IBI features were significantly longer for infants cared for in incubators although these infants were chronologically younger ( p<0.001). When neurodevelopmental outcome of the MLP and TC groups were compared at 4 and 18 months PMA, the MLP infant group achieved lower scores than in overall general development. The greatest differences were in the area of gross motor development (p <0.001, with a Cohen’s d effect size of -0.665), eye-hand coordination (p<0.001, with a Cohen’s d effect size of -0.648). Using the reported Griffith’s cut off of < 90 for delayed development, 7% (5/75) of the MLP group had delayed development at 18mths compared to 2% (2/92) of the TC group. Conclusion EEG provides an objective insight into sleep organisation and may be considered a biomarker of brain development. This thesis provides detailed analysis of the sleep EEG of a cohort of healthy MLP infant at 36 weeks PMA and provides useful reference criteria for studies that may assess brain maturation in the future, particularly for those infants in neonatal intensive care units.
dc.description.statusNot peer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationRyan, M. A. 2023. Sleep and developmental outcome of the moderate to late preterm infant. PhD Thesis, University College Cork.
dc.identifier.endpage282
dc.identifier.urihttps://hdl.handle.net/10468/15935
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2023, Mary Anne Ryan.en
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subjectPremature infant - low risken
dc.subjectModerate to late preterm infanten
dc.subjectEEG monitoring and featuresen
dc.subjectDevelopmental outcome at 4 months and 18 mthsen
dc.subjectGriffiths lll mental developmental scalesen
dc.titleSleep and developmental outcome of the moderate to late preterm infanten
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD - Doctor of Philosophyen
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