Ka-li Kwok

Childhood sleep‐disordered breathing and its implications for cardiac and vascular diseases

Objective: To systematically evaluate the recent literature regarding the relationship between childhood sleep‐disordered breathing (SDB)/obstructive sleep apnoea (OSA) and cardiovascular diseases in children.

An update on childhood snoring

Habitual snoring or daily snoring is a symptom of sleep‐disordered breathing (SDB) in children and it is reported in about 10% of children. SDB includes primary snoring, upper airway resistance syndrome (UARS), obstructive hypoventilation syndrome and obstructive sleep apnea syndrome (OSAS). Classification of SDB in a particular snoring child requires an overnight polysomnography (PSG). Manual scoring of PSG is mandatory in children. Risk factors for SDB include allergic rhinitis, passive smoking, obesity, dysmorphic syndromes and neuromuscular disorders. Conclusion: Treatment includes general measures like treatment of allergic rhinitis, weight reduction in obese children, and avoidance of sleep deprivation. Specific measures include removal of adenoid and tonsils. Complications of SDB include neurocognitive impairment, hypertension and failure to thrive.

Heart rate variability in childhood obstructive sleep apnea.

The identification of patients with obstructive sleep apnea (OSA) is important because of morbidities associated with OSA. A previous adult study demonstrated the use of heart rate variability (HRV) as a tool to identify patients with moderate to severe OSA. Either a reduction in time parameters or an increase in LF/HF ratio was seen at overnight or 24‐hr studies suggestive of increased sympathetic modulation. To study the feasibility of daytime HRV as a screening tool, a short‐term recording of HRV is studied. Since it was shown in adult study that increased normalized LF, decreased normalized HF and increased LF/HF ratio could be detectable during supine rest at daytime awake period, the authors hypothesize that the differences are also detectable in children. Children who underwent sleep polysomnography for suspected OSA were recruited. Subjects were classified OSA if apnea‐hypopnea index (AHI) > 1.5/hr and non‐OSA if AHI ≤ 1.5/hr. Continuous 1‐hr electrocardiographic monitoring was recorded in awake children during the day. Parameters from time domain and frequency domain were analyzed. Seventy‐four male and 17 female snoring subjects were included in this study. Fifty‐one (56%) and 40 (44%) of them were classified as “non‐OSA” and “OSA,” respectively. pNN50, a parameter for parasympathetic modulation, was significantly reduced in the OSA group when compared with the non‐OSA group. Using multiple regression, all time domain variables were shown to be decreased in OSA group. Our results suggest that 1‐hr study of HRV may be a feasible tool in identifying children with OSA. Pediatr Pulmonol. 2011; 46:205–210.

A brief report on the normal range of forehead temperature as determined by noncontact, handheld, infrared thermometer.

Background Noncontact forehead temperature measurement by handheld infrared thermometer was used as a screening tool for fever. However, the accuracy data and normal range of forehead temperature determined by this method were not available. Methods The temperature readings from 3 handheld infrared thermometers were validated against an electronic thermometer. Normal range of forehead temperature was determined by measuring the forehead temperature in 1000 apparently healthy subjects. Results Significant differences were detected in readings obtained by the 3 different handheld infrared thermometers (analysis of covariance, P < .001) The most accurate one was chosen, and the normal range of forehead temperature in 1000 subjects detected by this method was 31.0°C to 35.6°C. Conclusions Our study shows that commercially available, handheld infrared thermometers require individual validation. Forehead temperature in excess of 35.6°C is suggestive of fever. Further studies are required to confirm accuracy of this value in detecting fever.

Improvement in quality of life after adenotonsillectomy in a child with Prader Willi syndrome

IntroductionWe report a child with Prader Willi syndrome who developed obstructive sleep apnea (OSA). This patient underwent surgical treatment for OSA. There was improvement not only on her OSA but in her quality of life score as well. This report highlights the need for a comprehensive assessment in the management of patients with Prader Willi syndrome.

Maternally inherited Leigh syndrome: an unusual cause of infantile apnea.

IntroductionLeigh Syndrome is an uncommon cause of infantile apnea.Case summaryWe report a 5-month-old girl with sudden respiratory arrest followed by episodic hyper- and hypo-ventilation, encephalopathy, and persistent lactic acidosis. Computed tomography of the brain revealed symmetric low densities over the basal ganglia, internal capsule, thalami, and midbrain. Cardiac echocardiogram was suggestive of hypertrophic cardiomyopathy.DiscussionDiagnosis of Leigh syndrome due to T8993G mutation was confirmed with polymerase chain reaction and direct DNA sequencing of mitochondrial genome. To our knowledge, this is the first report of proven maternally inherited Leigh syndrome in Hong Kong.

Possible Confounding Factors in an Oral Probiotics Trial: Breast Milk

ing formula: HOMA-IR (insulin [mU/L] glucose [mmol/L])/ 22.5. Weight loss was achieved in the patients by physical exercise, a low-fat, high-carbohydrate diet, and behavioral therapy. Of the 5 children losing weight, 4 (patients 1, 3, 4, and 5) were initially treated with metformin over 6 months and none with insulin. None of the patients needed medication after weight loss. An important question is how adipose tissue can lead to insulin resistance, impaired glucose tolerance, and type 2 diabetes mellitus. The adipose tissue–derived hormones adiponectin, visfatin, and leptin are thought to be the link between insulin resistance and adipose tissue.5,6 Although increasing leptin levels are hypothesized to impair insulin sensitivity, decreasing adiponectin levels are postulated to decrease insulin sensitivity. In the meanwhile, we could demonstrate in additional studies of obese children that a reduction of 0.5 SDS BMI ( 30% reduction of the overweight) was associated with a significant increase in adiponectin concentrations and a significant decrease in leptin levels parallel to an improvement of insulin sensitivity.7,8 These findings integrate with the clinical data of improvement in insulin sensitivity resulting from a reduction of overweight by 30%. We have to keep in mind that the sample sizes in the Santoro et al study and of our diabetic patients are very small. Probably a lower degree of weight loss will lead to significant improvement of insulin sensitivity in larger collectives, as well. However, we can conclude that at least a reduction of 30% overweight or 0.5 SDS BMI based on the German BMI percentile2 (which is a reduction of BMI of 2 or a stable weight over a 1-year period among growing children) is associated with a clinically relevant improvement of insulin sensitivity in obese children, obese children with impaired glucose tolerance, and obese children with type 2 diabetes mellitus.