Flow Limitation Is Associated with Excessive Daytime Sleepiness in Individuals without Moderate or Severe Obstructive Sleep Apnea.

Rationale: Moderate-Severe Obstructive Sleep Apnea (OSA, AHI>15) disturbs sleep through frequent bouts of apnea and is associated with daytime sleepiness. However, many individuals without moderate-severe OSA (i.e., AHI<15) also report sleepiness. Objective: To test the hypothesis that sleepiness in the AHI<15 group is a consequence of substantial flow limitation, in the absence of overt reductions in airflow (i.e., apnea/hypopnea). Methods: N=1886 participants from the MESA sleep cohort were analyzed for frequency of flow limitation from polysomnogram recorded nasal airflow signal. Excessive daytime sleepiness (EDS) was defined by Epworth Sleepiness Scale ≥11. Covariate-adjusted logistic regression assessed the association between EDS (binary dependent variable) and frequency of flow limitation (continuous) in individuals with an AHI<15. Results: N=772 individuals with an AHI<15 were included in primary analysis. Flow limitation was associated with EDS (odds ratio of 2.04, CI95% [1.17-3.54], per 2 standard deviation (2SD) increase in flow limitation frequency) after adjusting for age, sex, BMI, race/ethnicity, and sleep duration. This effect size did not appreciably change after additionally adjusting for AHI. Conclusions: In individuals with an AHI<15, increasing flow limitation frequency by 2SD is associated with a 2-fold increase in risk of EDS. Future studies should investigate addressing flow limitation in low AHI individuals as a potential mechanism for ameliorating sleepiness.

Increased Flow Limitation During Sleep Is Associated With Increased Psychomotor Vigilance Task Lapses in Individuals With Suspected OSA.

BACKGROUND: Impaired daytime vigilance is an important consequence of OSA, but several studies have reported no association between objective measurements of vigilance and the apnea-hypopnea index (AHI). Notably, the AHI does not quantify the degree of flow limitation, that is, the extent to which ventilation fails to meet intended ventilation (ventilatory drive). RESEARCH QUESTION: Is flow limitation during sleep associated with daytime vigilance in OSA? STUDY DESIGN AND METHODS: Nine hundred ninety-eight participants with suspected OSA completed a 10-min psychomotor vigilance task (PVT) before same-night in-laboratory polysomnography. Flow limitation frequency (percent of flow-limited breaths) during sleep was quantified using airflow shapes (eg, fluttering and scooping) from nasal pressure airflow. Multivariable regression assessed the association between flow limitation frequency and the number of lapses (response times > 500 ms, primary outcome), adjusting for age, sex, BMI, total sleep time, depression, and smoking status. RESULTS: Increased flow limitation frequency was associated with decreased vigilance: a 1-SD (35.3%) increase was associated with 2.1 additional PVT lapses (95% CI, 0.7-3.7; P = .003). This magnitude was similar to that for age, where a 1-SD increase (13.5 years) was associated with 1.9 additional lapses. Results were similar after adjusting for AHI, hypoxemia severity, and arousal severity. The AHI was not associated with PVT lapses (P = .20). In secondary exploratory analysis, flow limitation frequency was associated with mean response speed (P = .012), median response time (P = .029), fastest 10% response time (P = .041), slowest 10% response time (P = .018), and slowest 10% response speed (P = .005). INTERPRETATION: Increased flow limitation during sleep was associated with decreased daytime vigilance in individuals with suspected OSA, independent of the AHI. Flow limitation may complement standard clinical metrics in identifying individuals whose vigilance impairment most likely is explained by OSA.

The characteristics of SARS-CoV-2-positive children in Australian hospitals: a PREDICT network study.

OBJECTIVES: To examine the clinical characteristics and short term outcomes for children with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections who presented to Australian hospitals during 2020 and 2021. DESIGN, SETTING: Retrospective case review study in nineteen hospitals of the Paediatric Research in Emergency Departments International Collaborative (PREDICT) network from all Australian states and territories, including seven major paediatric tertiary centres and eight Victorian hospitals. PARTICIPANTS: SARS-CoV-2-positive people under 18 years of age who attended emergency departments or were admitted to hospital during 1 February 2020 - 31 December 2021. MAIN OUTCOME MEASURES: Epidemiological and clinical characteristics, by hospital care type (emergency department [ED] or inpatient care). RESULTS: A total of 1193 SARS-CoV-2-positive children and adolescents (527 girls, 44%) attended the participating hospitals (107 in 2020, 1086 in 2021). Their median age was 3.8 years (interquartile range [IQR], 0.8-11.4 years); 63 were Aboriginal or Torres Strait Islander people (5%). Other medical conditions were recorded for 293 children (25%), including asthma (86, 7%) and premature birth (68, 6%). Medical interventions were not required during 795 of 1181 ED presentations (67%); children were discharged directly home in 764 cases (65%) and admitted to hospital in 282 (24%; sixteen to intensive care units). The 384 admissions to hospital (including 102 direct admissions) of 341 children (25 infants under one month of age) included 23 to intensive care (6%); the median length of stay was three days (IQR, 1-9 days). Medical interventions were not required during 261 admissions (68%); 44 children received respiratory support (11%) and 21 COVID-19-specific treatments, including antiviral and biologic agents (5%). Being under three months of age (v one year to less than six years: odds ratio [OR], 2.6; 95% confidence interval [CI], 1.7-4.0) and pre-existing medical conditions (OR, 2.5; 95% CI, 1.9-3.2) were the major predictors of hospital admission. Two children died, including one without a known pre-existing medical condition. CONCLUSION: During 2020 and 2021, most SARS-CoV-2-positive children and adolescents who presented to participating hospitals could be managed as outpatients. Outcomes were generally good, including for those admitted to hospital.

Frequency of flow limitation using airflow shape.

STUDY OBJECTIVES: The presence of flow limitation during sleep is associated with adverse health consequences independent of obstructive sleep apnea (OSA) severity (apnea-hypopnea index, AHI), but remains extremely challenging to quantify. Here we present a unique library and an accompanying automated method that we apply to investigate flow limitation during sleep. METHODS: A library of 117,871 breaths (N = 40 participants) were visually classified (certain flow limitation, possible flow limitation, normal) using airflow shape and physiological signals (ventilatory drive per intra-esophageal diaphragm EMG). An ordinal regression model was developed to quantify flow limitation certainty using flow-shape features (e.g. flattening, scooping); breath-by-breath agreement (Cohen's ƙ); and overnight flow limitation frequency (R2, %breaths in certain or possible categories during sleep) were compared against visual scoring. Subsequent application examined flow limitation frequency during arousals and stable breathing, and associations with ventilatory drive. RESULTS: The model (23 features) assessed flow limitation with good agreement (breath-by-breath ƙ = 0.572, p < 0.001) and minimal error (overnight flow limitation frequency R2 = 0.86, error = 7.2%). Flow limitation frequency was largely independent of AHI (R2 = 0.16) and varied widely within individuals with OSA (74[32-95]%breaths, mean[range], AHI > 15/h, N = 22). Flow limitation was unexpectedly frequent but variable during arousals (40[5-85]%breaths) and stable breathing (58[12-91]%breaths), and was associated with elevated ventilatory drive (R2 = 0.26-0.29; R2 < 0.01 AHI v. drive). CONCLUSIONS: Our method enables quantification of flow limitation frequency, a key aspect of obstructive sleep-disordered breathing that is independent of the AHI and often unavailable. Flow limitation frequency varies widely between individuals, is prevalent during arousals and stable breathing, and reveals elevated ventilatory drive. Clinical trial registration: The current observational physiology study does not qualify as a clinical trial.

Evaluation of an educational video providing key messages for doctors to counsel families following a first afebrile seizure.

AIM: The aim was to evaluate an educational video in educating doctors on the key messages and follow-up pathways following a first afebrile seizure presentation. A multidisciplinary expert team developed the video (http://www.pennsw.org.au/families/resources/first-seizure-pack-and-video) based on available evidence and best-practice. It contains a role-play between the parent/child and physician. It addresses: key messages to impart following a first seizure, seizure first aid, safety messages including necessary precautions post-discharge, contents of the First Seizure Pack for families, follow-up pathway and issues for discussion with the paediatrician at a later appointment. METHODS: Paediatric/Emergency department (ED) trainees across three Australian sites were recruited during terms 1 and 2, 2019. A repeated measures design was used. Multilevel modelling analyses were performed. The primary outcome was clinician knowledge. Secondary outcomes were confidence in answering questions and counselling families. Qualitative data on the utility, strengths and weaknesses of the video were evaluated. RESULTS: A total of 127 participants consented, one withdrew prior to commencing. A total of 126 baseline surveys, 115 follow-up surveys and 45 1-month follow-up surveys were returned. Viewing the video significantly improved knowledge of key messages at immediate follow-up (P < 0.001) and 1-month follow-up (P = 0.048). Likewise, confidence was significantly improved; 96.5% of responders found the video useful, 90.3% were likely to use the resource in the future and 82% would change their approach to counselling. Most liked aspects of the resource were clarity/conciseness of the information (n = 70) and comprehensiveness (n = 38). CONCLUSION: This education video significantly improved clinician knowledge and confidence in counselling families following first seizure.

Factors predictive for computed tomography use and abnormality in paediatric head injuries in Australia and New Zealand.

OBJECTIVES: To investigate patient-level factors predictive for computed tomography of the brain (CTB) use and abnormality in head injured children in Australia and New Zealand. METHODS: Retrospective data from tertiary, urban/suburban and regional/rural EDs including factors predictive for CTB use and abnormality. RESULTS: Of 3072 children at 31 EDs, 212 (6.9%) had a CTB scan, of which 66 (31%) were abnormal. Increasing age, serious mechanisms of injury and decreasing Glasgow Coma Score were predictive for ordering CTB. Decreasing age was predictive for CTB abnormalities. Other factors were not. CONCLUSION: Patient-level drivers of CTB use in children in Australia and New Zealand are consistent with international data.

Quantifying the magnitude of pharyngeal obstruction during sleep using airflow shape.

RATIONALE AND OBJECTIVES: Non-invasive quantification of the severity of pharyngeal airflow obstruction would enable recognition of obstructive versus central manifestation of sleep apnoea, and identification of symptomatic individuals with severe airflow obstruction despite a low apnoea-hypopnoea index (AHI). Here we provide a novel method that uses simple airflow-versus-time ("shape") features from individual breaths on an overnight sleep study to automatically and non-invasively quantify the severity of airflow obstruction without oesophageal catheterisation. METHODS: 41 individuals with suspected/diagnosed obstructive sleep apnoea (AHI range 0-91 events·h-1) underwent overnight polysomnography with gold-standard measures of airflow (oronasal pneumotach: "flow") and ventilatory drive (calibrated intraoesophageal diaphragm electromyogram: "drive"). Obstruction severity was defined as a continuous variable (flow:drive ratio). Multivariable regression used airflow shape features (inspiratory/expiratory timing, flatness, scooping, fluttering) to estimate flow:drive ratio in 136 264 breaths (performance based on leave-one-patient-out cross-validation). Analysis was repeated using simultaneous nasal pressure recordings in a subset (n=17). RESULTS: Gold-standard obstruction severity (flow:drive ratio) varied widely across individuals independently of AHI. A multivariable model (25 features) estimated obstruction severity breath-by-breath (R2=0.58 versus gold-standard, p<0.00001; mean absolute error 22%) and the median obstruction severity across individual patients (R2=0.69, p<0.00001; error 10%). Similar performance was achieved using nasal pressure. CONCLUSIONS: The severity of pharyngeal obstruction can be quantified non-invasively using readily available airflow shape information. Our work overcomes a major hurdle necessary for the recognition and phenotyping of patients with obstructive sleep disordered breathing.

Cyclists' clothing and reduced risk of injury in crashes.

INTRODUCTION: A majority of cyclists' hospital presentations involve relatively minor soft tissue injuries. This study investigated the role of clothing in reducing the risk of cyclists' injuries in crashes. METHODS: Adult cyclists were recruited and interviewed through hospital emergency departments in the Australian Capital Territory. This paper focuses on 202 who had crashed in transport related areas. Eligible participants were interviewed and their self-reported injuries corroborated with medical records. The association between clothing worn and injury was examined using logistic regression while controlling for potential confounders of injury. RESULTS: A high proportion of participants were wearing helmets (89%) and full cover footwear (93%). Fewer wore long sleeved tops (43%), long pants (33%), full cover gloves (14%) or conspicuity aids (34%). The primary cause of injury for the majority of participants (76%) was impact with the ground. Increased likelihood of arm injuries (Adj. OR=2.06, 95%CI: 1.02-4.18, p=0.05) and leg injuries (Adj. OR=3.37, 95%CI: 1.42-7.96, p=0.01) were associated with wearing short rather than long sleeves and pants. Open footwear was associated with increased risk of foot or ankle injuries (Adj. OR=6.21, 95%CI: 1.58-23.56, p=0.01) compared to enclosed shoes. Bare hands were associated with increased likelihood of cuts, lacerations or abrasion injuries (Adj. OR=4.62, 95%CI: 1.23-17.43, p=0.02) compared to wearing full cover gloves. There were no significant differences by fabric types such as Lycra/synthetic, natural fiber or leather. CONCLUSIONS: Clothing that fully covers a cyclist's body substantially reduced the risk of injuries in a crash. Coverage of skin was more important than fabric type. Further work is necessary to determine if targeted campaigns can improve cyclists' clothing choices and whether impact protection can further reduce injury risk.

Bicycle crashes in different riding environments in the Australian capital territory.

INTRODUCTION: Cyclists are increasingly overrepresented in traffic crash casualties in Australia. There is evidence that better cycling infrastructure increases participation, but whether it reduces the numbers of injured cyclists is less clear. This study examined injury outcomes of crashes in different cycling environments. METHODS: Adult cyclists injured on- and off-road were recruited from emergency departments from November 2009 to May 2010 in the Australian Capital Territory. Eligible participants (n = 313/372, 84.1%) were interviewed and their injury self-reports were corroborated with medical records where available. Participants who had crashed in transport-related areas (n = 202, 64.5%) are the focus of this article. RESULTS: Participants had crashed in traffic (39.1%), in cycle lanes (7.9%), on shared paths (36.1%), and on footpaths (16.8%). Based on average weekly traffic counts, the crash involvement rate per 1000 cyclists was 11.8 on shared paths compared to 5.8 on cycle lanes. Over half of the participants (52.0%) were injured in single-vehicle bicycle crashes. The remainder involved other road users, including motor vehicles (20.8%), other bicycles (18.8%), pedestrians (6.4%), and animals (2.0%). Pedestrians were involved in 16.4 percent of crashes on shared paths. Minor injuries (Abbreviated Injury Scale [AIS] 1) were sustained by 58.4 percent of cyclists, moderately severe injuries (AIS 2) were sustained by 36.1 percent of cyclists, and 5.4 percent of cyclists were seriously injured (AIS 3+). The average treatment required was 1.8 days with 7.5 days off work and cost to the cyclist of $869 excluding medical treatment. Cyclists who crashed on shared paths or in traffic had higher injury severity scores (ISS; 4.4, 4.0) compared to those in cycle lanes or on footpaths (3.3, 3.4) and required more treatment days (2.8, 1.7 versus 0.0, 0.2). CONCLUSIONS: Fewer cyclists were injured in on-road cycle lanes than in other cycling environments, and a high proportion of injuries were incurred on shared paths. This study highlights an urgent need to determine appropriate criteria and management strategies for paths classified as suitable for shared or segregated usage. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental files.