Relationships between ventilatory impairment,sleep hypoventilation and type 2 respiratory failure

Conditions that increase load on respiratory muscles and/or reduce their capacity to cope with this load predispose to type 2 (hypercapnic) respiratory failure. In its milder forms, this imbalance between load and capacity may primarily manifest as sleep hypoventilation which, if untreated, can increase the likelihood of wakeful respiratory failure. Such problems are commonly seen in progressive respiratory neuromuscular disorders, morbid obesity and chronic obstructive pulmonary disease, either separately or together. Identifying patients at risk can be important in determining whether and when to intervene with treatments such as non‐invasive ventilatory assistance. Measurements of wakeful respiratory function are fundamental to this risk assessment. These issues are reviewed in this paper.     

‘They said it was bronchiolitis; is it going to turn into asthma doctor?’

Acute bronchiolitis is a common paediatric disease of infancy. Its association with subsequent asthma development has puzzled clinicians and epidemiologists for decades. This article reviews the current state of knowledge regarding the role of acute bronchiolitis in the inception of asthma. There is little doubt that acute bronchiolitis is associated with an increased risk of recurrent wheezing throughout the primary school years although the direction of causality—i.e. whether bronchiolitis in infancy leads to asthma or it merely represents the first clinical presentation of predisposition to asthma—is uncertain. Existing evidence suggests that both host factors (e.g. prematurity, atopic predisposition) and acute viral infection characteristics (e.g. type of virus, severity) are operating in this relationship, perhaps with variable involvement in different individuals. Further clarification of these issues will help paediatricians provide evidence‐based information regarding the long‐term prognosis of this common disease to the families, and at the same time, it will facilitate prophylactic approaches and therapeutic strategies.     

Community use of face masks and similar barriers to prevent respiratory illness such as COVID-19: a rapid scoping review

BackgroundEvidence for face-mask wearing in the community to protect against respiratory disease is unclear.AimTo assess effectiveness of wearing face masks in the community to prevent respiratory disease, and recommend improvements to this evidence base.MethodsWe systematically searched Scopus, Embase and MEDLINE for studies evaluating respiratory disease incidence after face-mask wearing (or not). Narrative synthesis and random-effects meta-analysis of attack rates for primary and secondary prevention were performed, subgrouped by design, setting, face barrier type, and who wore the mask. Preferred outcome was influenza-like illness. Grading of Recommendations, Assessment, Development and Evaluations (GRADE) quality assessment was undertaken and evidence base deficits described.Results33 studies (12 randomised control trials (RCTs)) were included. Mask wearing reduced primary infection by 6% (odds ratio (OR): 0.94; 95% CI: 0.75–1.19 for RCTs) to 61% (OR: 0.85; 95% CI: 0.32–2.27; OR: 0.39; 95% CI: 0.18–0.84 and OR: 0.61; 95% CI: 0.45–0.85 for cohort, case–control and cross-sectional studies respectively). RCTs suggested lowest secondary attack rates when both well and ill household members wore masks (OR: 0.81; 95% CI: 0.48–1.37). While RCTs might underestimate effects due to poor compliance and controls wearing masks, observational studies likely overestimate effects, as mask wearing might be associated with other risk-averse behaviours. GRADE was low or very low quality.ConclusionWearing face masks may reduce primary respiratory infection risk, probably by 6–15%. It is important to balance evidence from RCTs and observational studies when their conclusions widely differ and both are at risk of significant bias. COVID-19-specific studies are required.