Chloe Parsley

University of Queensland, Brisbane, Queensland, Australia

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Publications (9)18.59 Total impact

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    ABSTRACT: Objective Pulse oximetry is used extensively in hospital and home settings to measure arterial oxygen saturation (SpO2). Interpretation of the trend and range of SpO2 values observed in infants is currently limited by a lack of reference ranges using current devices, and may be augmented by development of cumulative frequency (CF) reference-curves. This study aims to provide reference oxygen saturation values from a prospective longitudinal cohort of healthy infants. Design Prospective longitudinal cohort study. Setting Sleep-laboratory. Patients 34 healthy term infants were enrolled, and studied at 2 weeks, 3, 6, 12 and 24 months of age (N=30, 25, 27, 26, 20, respectively). Interventions Full overnight polysomnography, including 2 s averaging pulse oximetry (Masimo Radical). Main outcome measurements Summary SpO2 statistics (mean, median, 5th and 10th percentiles) and SpO2 CF plots were calculated for each recording. CF reference-curves were then generated for each study age. Analyses were repeated with sleep-state stratifications and inclusion of manual artefact removal. Results Median nocturnal SpO2 values ranged between 98% and 99% over the first 2 years of life and the CF reference-curves shift right by 1% between 2 weeks and 3 months. CF reference-curves did not change with manual artefact removal during sleep and did not vary between rapid eye movement (REM) and non-REM sleep. Manual artefact removal did significantly change summary statistics and CF reference-curves during wake. Conclusions SpO2 CF curves provide an intuitive visual tool for evaluating whether an individual's nocturnal SpO2 distribution falls within the range of healthy age-matched infants, thereby complementing summary statistics in the interpretation of extended oximetry recordings in infants.
    Archives of Disease in Childhood 07/2014; 100(1). DOI:10.1136/archdischild-2013-305708 · 2.91 Impact Factor
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    ABSTRACT: Non-invasive monitoring of breathing is a holy grail in paediatric respiratory, neonatal and sleep medicine. Respiratory rate is a key marker for the surveillance of sick infants and children (1-3), while repeated infant apnoeic episodes are associated with an increased risk of apparent life-threatening events (4). In clinical pulse oximetry, the photoplethysmographic (pleth) signal is assessed mainly to infer the validity of measured arterial oxygen saturation. This article is protected by copyright. All rights reserved.
    Acta Paediatrica 01/2014; 103(5). DOI:10.1111/apa.12575 · 1.84 Impact Factor
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    The 24th Annual Scientific meeting of the Australasian Sleep Association and the Australasian Sleep Technologists Association, Darwin, Australia; 10/2012
  • Australian Biomedical Engineering Conference, Brisbane, Australia; 09/2012
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    ABSTRACT: This study characterises and describes the maturational evolution of the healthy infant sleep electroencephalogram (EEG) longitudinally from 2 weeks to 24 months of age, by means of power spectral analysis. A prospective cohort of 34 healthy infants underwent overnight polysomnography (PSG) at 2 weeks, and at 3, 6, 12 and 24 months of age. Sleep epochs were scored as Active Sleep (AS) and Quiet Sleep (QS) at 2 weeks of age and as Rapid Eye Movement (REM) and Non-REM (NREM) stages from 3 months onwards. Representative epochs were used to generate the EEG power spectra, from the central C3 derivation. These were analysed visually and quantitatively in AS/REM and QS/NREM sleep in the following bandwidths: delta (0.5-4 Hz); theta (4-8 Hz); alpha (8-11 Hz); sigma (11-15 Hz) and 0.5-25 Hz. Sleep EEG (central derivation) power spectra changed significantly in the different bandwidths as the infants matured. The emergence of a peak in the sigma bandwidth in NREM N2 sleep corresponded with the development of sleep spindles. Maturational changes were also seen in NREM N3 and in theta and alpha bandwidths in both AS/REM and QS/NREM. Sleep EEG power spectra characteristics in healthy infants evolve in keeping with maturation and neurodevelopmental milestones. This study provides an atlas of healthy infant sleep EEG in the early years of life, providing a basis for association with other neurodevelopmental measures and a normative dataset on which disease may be discriminated.
    Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 02/2011; 122(2):236-43. DOI:10.1016/j.clinph.2010.06.030 · 2.98 Impact Factor
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    D. S. Urquhart · P. Wales · C. Parsley · S. Suresh
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    ABSTRACT: Background Children with Prader–Willi syndrome (PWS) are known to have sleep-disordered breathing. In addition to hypersomnolence and obstructive sleep apnoea, central respiratory control abnormalities may be present from infancy. The aims of this study were to describe breathing patterns in infants with PWS, and the effects of supplemental oxygen in this group. Methods Children with PWS attending a tertiary sleep clinic underwent full polysomnographic studies either to investigate persisting neonatal oxygen requirement, or as screening for sleep-disordered breathing. Continuous oxygen saturations (SpO2) and transcutaneous carbon dioxide (tcCO2) were recorded. Central and obstructive events were defined in accordance with the American Academy of Sleep Medicine (AASM) 2007 scoring rules. Children who had significant hypoxia associated with central events were started on supplemental oxygen during sleep and followed at 3-monthly intervals with split-night studies (periods in both air and supplemental oxygen). Paired t-tests were used to compare sleep data in air and oxygen arms for our subject cohort. Results 30 split-night studies were undertaken on 10 infants (8 female) aged 0.06–1.79 (mean 0.79, SD 0.44) years. At baseline (ie, air), children with PWS had a mean (SD) central apnoea index (CAI) of 6.9 (6.3) per hour, with accompanying falls in SpO2. Oxygen therapy led to statistically significant reductions in CAI, as well as improved SpO2 (Abstract P198 Table 1). No significant change in the number of obstructive events was noted. Discussion Infants with PWS have sleep-disordered breathing problems, which are predominantly central in origin, and cause significant hypoxia in some patients. Improvements in both central event indices and oxygenation were noted on oxygen therapy. Longitudinal work with this patient group would help to establish timing of onset of obstructive symptoms. Whether early recognition of central hypoventilation, and correction with oxygen alter the evolution of respiratory dysfunction and excessive daytime somnolence in later life remains to be seen.
    Thorax 11/2010; 65(Suppl 4):A160-A161. DOI:10.1136/thx.2010.151043.49 · 8.56 Impact Factor
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    ABSTRACT: In adults, ventilation is preferentially distributed towards the dependent lung. A reversal of the adult pattern has been observed in infants using radionuclide ventilation scanning. But these results have been obtained in infants and children with lung disease. In this study we investigate whether healthy infants have a similar reverse pattern of ventilation distribution. Measurement of regional ventilation distribution in healthy newborn infants during non-REM sleep in comparison to adults. Twenty-four healthy newborns and 13 adults were investigated with electrical impedance tomography (EIT) in supine and prone position. Regional ventilation distribution was assessed with profiles of relative impedance change. The phase lag between dependent and non-dependent ventilation was calculated as a measure of asynchronous ventilation. In newborns and adults the geometric center of ventilation was centrally located in the lung at 52.2 +/- 6.2% from anterior to posterior and at 50.5 +/- 14.7%, respectively. Using impedance profiles, ventilation was equally distributed to the dependent and non-dependent lung regions in newborns. Ventilation distribution in adults was similar. Phase lag characteristics of the impedance signal showed that infants had slower emptying of the dependent lung than adults. The speculated reverse pattern of regional ventilation distribution in healthy infants compared to adults could not be demonstrated. Gravity had little effect on ventilation distribution in both infants and adults measured in supine and prone position.
    Pediatric Pulmonology 09/2009; 44(9):851-8. DOI:10.1002/ppul.21000 · 2.30 Impact Factor