Abstract
Introduction. Sleep disturbances in children can result from extrinsic learned behaviours that become poor sleep habits, or they can arise from intrinsically caused disorders that may require medical treatment. Some sleep problems, if left untreated, can have long-term consequences; therefore it is crucial that these problems are identified early and treated with the optimal method to ensure that children are receiving the best possible start to life and can develop to their full potential.
Extrinsic sleep problems are reported to affect between 20% and 30% of the paediatric population, and although there is a consensus within the existing literature that these poor sleep behaviours impact negatively on child development, there are very limited data on how a child’s problematic sleep affects other family members. Therefore the first part of this thesis aims to explore through qualitative research methods the attitudes, opinions and feelings of mothers who perceive their child's sleep to be problematic.
Sleep Disordered Breathing (SDB), one of the most common intrinsic sleep disorders, affects around 10% of children. Its diagnosis and severity can be ascertained from the Apnoea-Hypopnoea Index (AHI) using the current gold-standard technique of polysomnography (PSG). However this technique is resource- and cost-intensive and consequently is not always performed in clinical settings. Alternative diagnostic tools are therefore being sought, and the measure of Pulse Transit Time (PTT) is showing promise. Inversely related to blood pressure, PTT repeatedly shortens as blood pressure increases in response to associated airway obstructions and autonomic arousals; however it is still unclear exactly how well PTT is associated to the AHI. The second part of thesis therefore aims to assess the value of PTT as a clinical screening tool by systematically reviewing the current paediatric sleep literature that has utilised the technique of PTT and by examining the correlation between the PTT arousal index (PTT-AI) and the AHI in children with suspected SDB before and after the treatment of adenotonsillectomy.
Methods and Results. Part One. Sixteen mothers of children aged three to four years who perceived their child’s sleep as problematic were recruited from the community. All participants completed a questionnaire regarding their child’s demographics and sleep habits, including at bedtime and during the night. Semi-structured interviews were then completed with the mothers, with questions organised around three main themes: the mother’s perception of their child’s sleep, their family functioning, and desired action for help and support. The analysis of the interviews was conducted inductively, allowing patterns, themes and categories to emerge, and was not based on pre-determined categories. All mothers identified difficulties with their child initiating and maintaining sleep during the night, with 34% of children refusing bedtime, 37% not staying in their bed the entire night, and 37% falling asleep in the presence of a parent. The interviews revealed five main emotions among participants: resignation, guilt or shame, confusion and frustration, exhaustion, and defeat. The majority of participants also believed their child’s sleep had detrimental effects on their partner and their other children. All mothers expressed a desire for help and support, with the majority indicating a desire for one-on-one support in the form of a sleep specialist or sleep support person.
Methods and Results. Part Two. A systematic review of all studies that used PTT as a diagnostic tool during sleep in infants, children or adolescents aged from birth to 18 years was conducted. A total of 21 full-text articles were included. Three prominent areas of research investigation emerged – the ability of PTT to (1) track changes in blood pressure (BP), (2) detect cortical Electroencephalography (EEG) arousals and sub-cortical non-EEG-related arousals, and (3) identify types of respiratory events and screen for Obstructive Sleep Apnoea (OSA) and severity. Studies that included PTT as an investigative measure of OSA or sleep-related arousals assessed PTT’s ability to identify obstructive and central apneic events and ultimately its feasibility as a diagnostic screening tool of OSA, with the majority reporting that PTT was as accurate as PSG in identifying respiratory or arousal events. PTT was also seen to allow the detection of sub-cortical arousals and improved the detection of respiratory events during sleep. The main limitation of PTT was its inability to identify mild OSA.
Forty children aged 4 to 11 years who were awaiting adenotonsillectomy were recruited from Dunedin Public Hospital ENT surgical lists. All participants underwent two nights of at-home sleep recordings – one prior to surgery and one three months after surgery. Parental questionnaires (Paediatric Sleep Questionnaire (PSQ), Paediatric Epworth Sleepiness Scale (ESS), Paediatric Quality of Life Inventory (PedsQL), and the Obstructive Sleep Apnoea Syndrome Quality of Life Survey (OSA-18)) were administered and clinical assessments made at each time point. An AHI, PTT-AI, oxygen desaturation index, clinical assessment and score for each questionnaire were produced for each participant and analysis conducted.
Receiver Operating Characteristic curve analysis revealed that the strongest association between PTT-AI and AHI was seen in children with an AHI >1 before surgery (AUC=0.55, 95%CI; 0.23, 0.87) with a sensitivity of 87% and a specificity of 50%. AHI, all clinical assessment scores and questionnaire scores significantly improved after treatment (p<0.001), and all clinical assessment scores and questionnaire scores were significantly associated with the AHI (PSQ (p<0.001), ESS (p=0.012), PedsQL (p=0.025), OSA-18 (p<0.001), and Clinical Assessment Score (p=0.001)). No clear relationship between PTT-AI and AHI was seen in the present study. Geometric mean PTT-AI values did not significantly change from before-surgery (μ=18, 95%CI; 14-23) to after-surgery conditions (μ=16, 95%CI; 14-20), and PTT-AI was not found to be significantly associated with any other measures.
Conclusion. A child’s problematic sleep can affect not only the child but, as Part One revealed, also a parent’s quality of sleep, daytime functioning and, most interestingly, emotions - something that has not been well reported on previously. Understanding the way parents and families respond emotionally to their pre-schooler’s sleep allows more accurate help and support for parents to be developed. This not only benefits the parents and other family members but will ultimately provide benefits for the child, increasing the likelihood of the development of healthy sleeping habits at a young age. Knowledge of these emotional responses will also aid in the future development of behavioural sleep interventions for pre-school-aged children.
Part Two revealed that PTT may have potential as a screening tool to determine which children do not have SDB and therefore do not require treatment for SDB, rather than which children do have SDB. PTT-AI was not seen to significantly change after treatment and no clear relationship was seen between PTT-AI and AHI; however PTT-AI was found to be most highly associated with an AHI>1 before surgery. All parental report questionnaires were also found to be significantly associated with the gold standard of AHI and scores significantly improved after treatment, supporting previous research that they could play an important role in the screening of children with suspected SDB for surgery in a clinical setting.