Snoring and its association with asthma in Indigenous children living in the Torres Strait and Northern Peninsula Area

Objective: Respiratory health of Indigenous and minority ethnic groups in affluent countries is poorer than their non-minority counterparts and sleep disorders are no exception. In children, obstructive sleep apnoea has the potential to result in serious long-term consequences. In 1999, we studied 1650 children and adolescents living in the Torres Strait and the Northern Peninsula Area, Australia. Here we report prevalence of snoring in these communities and relate its association with asthma symptoms. Methods: A population-based cross-sectional study was conducted in the Torres Strait region. Five indigenous communities were randomly selected and information was collected using a structured face-to-face interview based on a standardized questionnaire. There was a 98% response rate, and 1650 children, 0-17 years of age, were included in the study. Results: Overall, the prevalence of snoring was 14.2% (95% CI 12.5-15.9); 3.6% (95% CI 2.7-4.6) reported snorting, and 6% (95% CI 4.9-7.2) reported restless sleep. The prevalence of snoring was significantly higher among males (17.1% for males and 10.8 for females, P = 0.005). Children were five times more likely to have experienced snoring and snorting if they reported wheezing in the last 12 months. Conclusion: We conclude that the prevalence of symptoms suggestive of obstructive sleep problems is relatively high in children of this region. This highlights the need for awareness among the community patients and physicians about the problem of obstructive sleep-disordered breathing, especially in children with asthma, and for the need for further studies to measure prevalence of sleep breathing disorders among Indigenous Australians.

Association of subclinical right ventricular dysfunction with obesity

OBJECTIVES The purpose of this research was to identify the determinants of right ventricular (RV) dysfunction in overweight and obese subjects. BACKGROUND Right ventricular dysfunction in obese subjects is usually ascribed to comorbid diseases, especially obstructive sleep apnea. We used tissue Doppler imaging to identify the determinants of RV dysfunction in overweight and obese subjects. METHODS Standard and tissue Doppler echocardiography was performed in 112 overweight (body mass index [BMI] 25 to 29.9 kg/m(2)) or obese (BMI >30 kg/m(1)) subjects and 36 referents (BMI 35 kg/m(2) had reduced RV function compared with referent subjects, evidenced by reduced s(m) (6.5 +/- 2.4 cm/s vs. 10.2 +/- 1.5 cm/s, p < 0.001), peak strain (-21 +/- 4% vs. -28 +/- 4%, p < 0.001), peak strain rate (-1.4 +/- 0.4 s(-1) vs. -2.0 +/- 0.5 s(-1), p < 0.001), and e(m) (6.8 +/- 2.4 cm/s vs. -10.3 +/- 2.5 cm/s, p < 0.001), irrespective of the presence of sleep apnea. Similar but lesser degrees of reduced systolic function (p < 0.05) were present in overweight (BMI 25 to 29.9 kg/m(2)) and mildly obese (BMI 30 to 35 kg/m(2)) groups. Differences in RV e(m), s(m), and strain indexes were demonstrated between the severely versus overweight and mildly obese groups (p < 0.05). Body mass index remained independently related to RV changes after adjusting for age, log insulin, and mean arterial pressures. In obese patients, these changes were associated with reduced exercise capacity but not the duration of obesity and presence of sleep apnea or its severity. CONCLUSIONS Increasing BMI is associated with increasing severity of RV dysfunction in overweight and obese subjects without overt heart disease, independent of sleep apnea.

Apnea diving: Long-term neurocognitive sequelae of repeated hypoxemia

This article examines the neurocognitive sequelae of repeated exposure to hypoxemia in apnea (breath-hold) divers. A brief review of the literature on the physiological and neurological adaptations involved in the human diving reflex is presented. The results from a neuropsychological investigation of N = 21 elite apnea divers are evaluated. Standard neuropsychological tests, with known sensitivity to mild brain insults, included speed of visuo-motor responding, speed of language comprehension, response inhibition, and visual and verbal attention and recall tasks. Results indicated that the breath-hold divers performed tasks within the average range compared to norms on all tests, suggesting that 1-20 years of repeated exposure to hypoxemia including multiple adverse neurological events did not impact on performance on standard neuropsychological tasks. The results are discussed in relation to implications for clinical conditions such as sleep apnea, respiratory disorders, altitude sickness, and recreational apnea activities.

Sleep-related breathing disorder in Duchenne muscular dystrophy: Disease spectrum in the paediatric population

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease with death usually occurring because of respiratory failure. Signs of early respiratory insufficiency are usually first detectable in sleep. Objective: To study the presentation of sleep-related breathing disorder (SRBD) in patients with DMD. Method:> A retrospective review of patients with DMD attending a tertiary paediatric sleep disorder clinic over a 5-year period. Symptoms, lung function and polysomnographic indices were reviewed. Results: A total of 34 patients with DMD were referred for respiratory assessment (1-15 years). Twenty-two (64%) reported sleep-related symptomatology. Forced vital capacity (FVC) was between 12 and 107% predicted (n = 29). Thirty-two progressed to have polysomnography of which 15 were normal studies (median age: 10 years) and 10 (31%) were diagnostic of obstructive sleep apnoea (OSA) (median age: 8 years). A total of 11 patients (32%) showed hypoventilation (median age: 13 years) during the 5-year period and non-invasive ventilation (NIV) was offered to them. The median FVC of this group was 27% predicted. There was a significant improvement in the apnoea/hypopnoea index (AHI) (mean difference = 11.31, 95% CI = 5.91-16.70, P = 0.001) following the institution of NIV. Conclusions: The prevalence of SRBD in DMD is significant. There is a bimodal presentation of SRBD, with OSA found in the first decade and hypoventilation more commonly seen at the beginning of the second decade. Polysomnography is recommended in children with symptoms of OSA, or at the stage of becoming wheelchair-bound. In patients with the early stages of respiratory failure, assessment with polysomnography-identified sleep hypoventilation and assisted in initiating NIV.

Variability in time delay between two models of pulse oximeters for deriving the photoplethysmographic signals

Pulse oximetry is commonly used as an arterial blood oxygen saturation (SaO(2)) measure. However, its other serial output, the photoplethysmography (PPG) signal, is not as well studied. Raw PPG signals can be used to estimate cardiovascular measures like pulse transit time (PTT) and possibly heart rate (HR). These timing-related measurements are heavily dependent on the minimal variability in phase delay of the PPG signals. Masimo SET (R) Rad-9 (TM) and Novametrix Oxypleth oximeters were investigated for their PPG phase characteristics on nine healthy adults. To facilitate comparison, PPG signals were acquired from fingers on the same hand in a random fashion. Results showed that mean PTT variations acquired from the Masimo oximeter (37.89 ms) were much greater than the Novametrix (5.66 ms). Documented evidence suggests that I ms variation in PTT is equivalent to I mmHg change in blood pressure. Moreover, the PTT trend derived from the Masimo oximeter can be mistaken as obstructive sleep apnoeas based on the known criteria. HR comparison was evaluated against estimates attained from an electrocardiogram (ECG). Novametrix differed from ECG by 0.71 +/- 0.58% (p < 0.05) while Masimo differed by 4.51 +/- 3.66% (p > 0.05). Modem oximeters can be attractive for their improved SaO(2) measurement. However, using raw PPG signals obtained directly from these oximeters for timing-related measurements warrants further investigations.

Realtime telemedicine for paediatric otolaryngology pre-admission screening

We conducted a feasibility study to examine whether a paediatric patient at a regional hospital could be assessed by an ear, nose and throat (ENT) specialist via videoconference, therefore saving at least one journey to the tertiary hospital for a pre-admission appointment. A video-otoscope was used with standard videoconference equipment, and realtime images were transmitted at a bandwidth of 384 kbit/s. In all, 13 telepaediatric ENT clinics were conducted between November 2003 and April 2005, and 98 consultations were facilitated for 64 patients. The main reasons for referral were recurrent tonsillitis (25%) and obstructive sleep apnoea (23%). Of the 64 patients examined by telemedicine, 42 (66%) were recommended for surgery and placed on the surgical waiting list. About 12 patients (19%) required travel to the tertiary centre for further investigations and tests not available locally, while four patients (6%) were reviewed via videoconference during a scheduled clinic. Six patients (9%) required no further follow-up after their initial telepaedliatric consultation. Videoconferencing is an effective method of assessing ENT conditions of paediatric patients and for pre-screening potential surgical admissions to a tertiary hospital. Careful consideration of a number of economic and logistical factors needs to be made before large investments are made to expand the service.

Left-right information flow in the brain during EEG arousals

In disorders such as sleep apnea, sleep is fragmented with frequent EEG-arousal (EEGA) as determined via changes in the sleep-electroencephalogram. EEGA is a poorly understood, complicated phenomenon which is critically important in studying the mysteries of sleep. In this paper we study the information flow between the left and right hemispheres of the brain during the EEGA as manifested through inter-hemispheric asynchrony (IHA) of the surface EEG. EEG data (using electrodes A1/C4 and A2/C3 of international 10-20 system) was collected from 5 subjects undergoing routine polysomnography (PSG). Spectral correlation coefficient (R) was computed between EEG data from two hemispheres for delta-delta(0.5-4 Hz), theta-thetas(4.1-8 Hz), alpha-alpha(8.1-12 Hz) & beta-beta(12.1-25 Hz) frequency bands, during EEGA events. EEGA were graded in 3 levels as (i) micro arousals (3-6 s), (ii) short arousals (6.1-10 s), & (iii) long arousals (10.1-15 s). Our results revealed that in beta band, IHA increases above the baseline after the onset of EEGA and returns to the baseline after the conclusion of event. Results indicated that the duration of EEGA events has a direct influence on the onset of IHA. The latency (L) between the onset of arousals and IHA were found to be L=2plusmn0.5 s (for micro arousals), 4plusmn2.2 s (short arousals) and 6.5plusmn3.6 s (long arousals)

Screening of obstructive and central apnoea/hypopnoea in children using variability: A preliminary study

Aim: Polysomnography (PSG) is the current standard protocol for sleep disordered breathing (SDB) investigation in children. Presently, there are limited reliable screening tests for both central (CE) and obstructive (OE) respiratory events. This study compared three indices, derived from pulse oximetry and electrocardiogram ( ECG), with the PSG gold standard. These indices were heart rate (HR) variability, arterial blood oxygen de-saturation (SaO(2)) and pulse transit time (PTT). Methods: 15 children (12 male) from routine PSG studies were recruited (aged 3 - 14 years). The characteristics of the three indices were based on known criteria for respiratory events (RPE). Their estimation singly and in combination was evaluated with simultaneous scored PSG recordings. Results: 215 RPE and 215 tidal breathing events were analysed. For OE, the obtained sensitivity was HR (0.703), SaO(2) (0.047), PTT (0.750), considering all three indices (0) and either of the indices (0.828) while specificity was (0.891), (0.938), (0.922), (0.953) and (0.859) respectively. For CE, the sensitivity was HR (0.715), SaO(2) (0.278), PTT (0.662), considering all indices (0.040) and either of the indices (0.868) while specificity was (0.815), (0.954), (0.901), (0.960) and (0.762) accordingly. Conclusions: Preliminary findings herein suggest that the later combination of these non-invasive indices to be a promising screening method of SDB in children.