Face Coverings, Aerosol Dispersion and Mitigation of Virus Transmission Risk.

The SARS-CoV-2 virus is primarily transmitted through virus-laden fluid particles ejected from the mouth of infected people. Face covers can mitigate the risk of virus transmission but their outward effectiveness is not fully ascertained. Objective: by using a background oriented schlieren technique, we aim to investigate the air flow ejected by a person while quietly and heavily breathing, while coughing, and with different face covers. Results: we found that all face covers without an outlet valve reduce the front flow through by at least 63% and perhaps as high as 86% if the unfiltered cough jet distance was resolved to the anticipated maximum distance of 2-3 m. However, surgical and handmade masks, and face shields, generate significant leakage jets that may present major hazards. Conclusions: the effectiveness of the masks should mostly be considered based on the generation of secondary jets rather than on the ability to mitigate the front throughflow.

Indirect effects of the COVID-19 pandemic on paediatric healthcare use and severe disease: a retrospective national cohort study.

OBJECTIVES: To determine the indirect consequences of the COVID-19 pandemic on paediatric healthcare utilisation and severe disease at a national level following lockdown on 23 March 2020. DESIGN: National retrospective cohort study. SETTING: Emergency childhood primary and secondary care providers across Scotland; two national paediatric intensive care units (PICUs); statutory death records. PARTICIPANTS: 273 455 unscheduled primary care attendances; 462 437 emergency department attendances; 54 076 emergency hospital admissions; 413 PICU unplanned emergency admissions requiring invasive mechanical ventilation; and 415 deaths during the lockdown study period and equivalent dates in previous years. MAIN OUTCOME MEASURES: Rates of emergency care consultations, attendances and admissions; clinical severity scores on presentation to PICU; rates and causes of childhood death. For all data sets, rates during the lockdown period were compared with mean or aggregated rates for the equivalent dates in 2016-2019. RESULTS: The rates of emergency presentations to primary and secondary care fell during lockdown in comparison to previous years. Emergency PICU admissions for children requiring invasive mechanical ventilation also fell as a proportion of cases for the entire population, with an OR of 0.52 for likelihood of admission during lockdown (95% CI 0.37 to 0.73), compared with the equivalent period in previous years. Clinical severity scores did not suggest children were presenting with more advanced disease. The greatest reduction in PICU admissions was for diseases of the respiratory system; those for injury, poisoning or other external causes were equivalent to previous years. Mortality during lockdown did not change significantly compared with 2016-2019. CONCLUSIONS: National lockdown led to a reduction in paediatric emergency care utilisation, without associated evidence of severe harm.

Airway epithelial cytokine responses in childhood wheeze are independent of atopic status.

BACKGROUND: Airway epithelial cells (AEC) are key contributors to immune function in the lungs but little is known about their role and function in children. OBJECTIVES: Having previously established that nasal AEC mediator release correlates with that of bronchial AEC, we assessed AEC responses in children with and without a history of wheeze. METHODS: Nasal AEC cultures were established from children (0.6-14.9 years) undergoing elective surgical procedures under general anaesthetic categorised as atopic asthmatic (n = 12), virus-induced wheeze (n = 8) or children without wheeze (n = 32). Mediator release by AEC monolayers at passage 2 was determined by cytometric bead array assay or ELISA. RESULTS: Unstimulated AEC from children with a history of wheeze produced significantly less IL-8, IL-6, MCP-1 and G-CSF than AEC from healthy controls. There were no group differences in AEC release of VEGF, RANTES, MMP-9 or TIMP-1. After stimulation with the pro-inflammatory cytokines IL-1ß and TNFα, AEC from children with current wheeze produced significantly less IL-8, IL-6 and MCP-1 than children without wheeze. Release of G-CSF, VEGF, MMP-9 and TIMP-1 did not differ between the wheeze and control group. There were no differences in mediator release between subjects with atopic asthma and those with virus-induced wheeze or between atopic and non-atopic controls. On multivariate analysis, wheeze was the only significant predictor of AEC mediator release. CONCLUSION & CLINICAL RELEVANCE: Intrinsic differences in AEC from children with a history of wheeze may reflect a defect in cytokine production in vivo or an altered state of differentiation in vitro, independent of atopic status.

Long-term ventilation in children: longitudinal trends and outcomes.

BACKGROUND: Cross-sectional studies have suggested a rapid expansion in paediatric long-term ventilation (LTV) over the last 20 years but information on longitudinal trends is limited. METHODS: Data were collected prospectively on all patients receiving LTV over a 15-year period (1.1.95-31.12.09) in a single regional referral centre. RESULTS: 144 children commenced LTV during the 15-year period. The incidence of LTV increased significantly over time, with an accompanying 10-fold increase in prevalence due to a significant increase in institution of non-invasive ventilation (NIV). There was no significant increase in invasive ventilation. 5-year survival was 94% overall and was significantly higher for patients on NIV (97%) than invasively ventilated patients (84%). 10-year survival was 91% overall. Although some children were able to discontinue respiratory support (21% at 5 years and 42% at 10 years), the number of patients transitioned to adult services increased significantly over time (26% of total cohort). Patients with neuromuscular disease were less likely to discontinue support than other patients. CONCLUSIONS: The paediatric LTV population has expanded significantly over 15 years. Future planning of paediatric hospital and community services, as well as adult services, must take into account the needs of this growing population.

Superior herniation of the mediastinum presenting as an anterior neck mass on straining.

We report an infant with an anterior neck mass present only on straining. Airway fluoroscopy revealed this to be due to superior mediastinal herniation. Neck masses apparent only during Valsalva maneuver are rare and awareness of the differential diagnosis is important to avoid unnecessary investigation or surgery.

Nasal epithelial cells as surrogates for bronchial epithelial cells in airway inflammation studies.

The nose is an attractive source of airway epithelial cells, particularly in populations in which bronchoscopy may not be possible. However, substituting nasal cells for bronchial epithelial cells in the study of airway inflammation depends upon comparability of responses, and evidence for this is lacking. Our objective was to determine whether nasal epithelial cell inflammatory mediator release and receptor expression reflect those of bronchial epithelial cells. Paired cultures of undifferentiated nasal and bronchial epithelial cells were obtained from brushings from 35 subjects, including 5 children. Cells were subject to morphologic and immunocytochemical assessment. Mediator release from resting and cytokine-stimulated cell monolayers was determined, as was cell surface receptor expression. Nasal and bronchial cells had identical epithelial morphology and uniform expression of cytokeratin 19. There were no differences in constitutive expression of CD44, intercellular adhesion molecule-1, alphavbeta3, and alphavbeta5. Despite significantly higher constitutive release of IL-8, IL-6, RANTES (regulated on activation, normal T cell expressed and secreted), and matrix metalloproteinase (MMP)-9 from nasal compared with bronchial cells, the increments in release of all studied mediators in response to stimulation with IL-1beta and TNF-alpha were similar, and there were significant positive correlations between nasal and bronchial cell secretion of IL-6, RANTES, vascular endothelial growth factor, monocyte chemoattractant protein-1, MMP-9, and tissue inhibitor of metalloproteinase-1. Despite differences in absolute mediator levels, the responses of nasal and bronchial epithelial cells to cytokine stimulation were similar, expression of relevant surface receptors was comparable, and there were significant correlations between nasal and bronchial cell mediator release. Therefore, nasal epithelial cultures constitute an accessible surrogate for studying lower airway inflammation.

Decreasing prevalence of obesity in primary schoolchildren.

The prevalence of obesity in a cohort of Scottish primary schoolchildren was assessed and compared with previous cohorts taken from the same geographical area. The prevalence of obesity has declined over the three time periods studied, from 14.7% to 10.2%. Body mass index (BMI) centiles and BMI standard deviation scores have also declined considerably over time.