Effects of testosterone and sex hormone binding globulin on lung function in males and females: a multivariable Mendelian Randomisation study

BACKGROUND

Observational studies suggest that total testosterone (TT) and sex hormone-binding globulin (SHBG) may have beneficial effects on lung function, but these findings might be spurious due to confounding and reverse causation. We addressed these limitations by using multivariable Mendelian randomisation (MVMR) to investigate the independent causal effects of TT and SHBG on lung function.

METHODS

We first identified genetic instruments by performing genome-wide association analyses of TT and SHBG in the large UK Biobank, separately in males and females. We then assessed the independent effects of TT and SHBG on forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC using one-sample MVMR. We addressed pleiotropy, which could bias MVMR, using several methods that account for it. We performed subgroup MVMR analyses by obesity, physical activity and menopausal status, and assessed associations between TT and SHBG with lung function decline. Finally, we compared the MVMR results with those of observational analyses in the UK Biobank.

FINDINGS

In the MVMR analyses, there was evidence of pleiotropy, but results were consistent when accounting for it. We found a strong beneficial effect of TT on FVC and FEV1 in both males and females, but a moderate detrimental effect of SHBG on FEV1 and FEV1/FVC in males only. Subgroup analyses suggested stronger effects of TT among obese and older males. The observational analyses, in line with previous studies, agreed with MRMV for TT, but not for SHBG.

INTERPRETATION

These findings suggest that testosterone improves lung function in males and females, while SHBG has an opposite independent effect in males.

Impact of ambient air pollution on lung function in preterm-born school-aged children

RATIONALE

Increased outdoor air pollution worsens lung function in children. However, these associations are less well studied in preterm-born individuals.

OBJECTIVES

We assessed associations between ambient air pollutants and spirometry measures in preterm-born children.

METHODS

The Respiratory Health Outcomes in Neonates study recruited preterm-born children aged 7-12 years who were born at ≤34 week's gestation. We associated four ambient air pollutants (particulate matter with aerodynamic diameter ≤2.5 µm (PM2.5), PM10, nitrogen dioxide (NO2) and sulfur dioxide) at time of birth and spirometry assessment and averaged exposure between these two time points with spirometry measures, using linear regression analyses. Gestational age was banded into 23-28, 29-31 and 32-34 week's. Regression models estimated spirometry values against pollutant levels at birth and at the time of spirometry.

MEASUREMENTS AND MAIN RESULTS

From 565 preterm-born children, 542 (96%) had satisfactory data. After adjustments for early and current life factors, significant detrimental associations were noted between PM10 at birth and per cent predicted forced vital capacity (%FVC) for the 23-28 and 29-31 week's gestation groups and between current PM2.5 and NO2 exposure and %FVC for the 23-28 week's gestation group. No associations with spirometry were noted for the averaged pollution exposure between birth and spirometry. Predictive models showed 5.9% and 7.4% differences in %FVC between the highest and lowest current pollution exposures for PM2.5 and NO2, respectively, in the 23-28 week group.

CONCLUSIONS

Birth and current exposures to road-traffic-associated pollutants detrimentally affected %FVC in preterm-born school-aged children, who already have compromised lung function.

Lung function trajectories from school age to adulthood and their relationship with markers of cardiovascular disease risk

RATIONALE

Lung function in early adulthood is associated with subsequent adverse health outcomes.

OBJECTIVES

To ascertain whether stable and reproducible lung function trajectories can be derived in different populations and investigate their association with objective measures of cardiovascular structure and function.

METHODS

Using latent profile modelling, we studied three population-based birth cohorts with repeat spirometry data from childhood into early adulthood to identify trajectories of forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC). We used multinomial logistic regression models to investigate early-life predictors of the derived trajectories. We then ascertained the extent of the association between the derived FEV1/FVC trajectories and blood pressure and echocardiographic markers of increased cardiovascular risk and stroke in ~3200 participants at age 24 years in one of our cohorts.

RESULTS

We identified four FEV1/FVC trajectories with strikingly similar latent profiles across cohorts (pooled N=6377): above average (49.5%); average (38.3%); below average (10.6%); and persistently low (1.7%). Male sex, wheeze, asthma diagnosis/medication and allergic sensitisation were associated with trajectories with diminished lung function in all cohorts. We found evidence of an increase in cardiovascular risk markers ascertained by echocardiography (including left ventricular mass indexed to height and carotid intima-media thickness) with decreasing FEV1/FVC (with p values for the mean crude effects per-trajectory ranging from 0.10 to p<0.001). In this analysis, we considered trajectories as a pseudo-continuous variable; we confirmed the assumption of linearity in all the regression models.

CONCLUSIONS

Childhood lung function trajectories may serve as predictors in the development of not only future lung disease, but also the cardiovascular disease and multimorbidity in adulthood.

Single and multiple breath nitrogen washout compared with the methacholine test in patients with suspected asthma and normal spirometry

BACKGROUND

Methods used to assess ventilation heterogeneity through inert gas washout have been standardised and showed high sensitivity in diagnosing many respiratory diseases. We hypothesised that nitrogen single or multiple breath washout tests, respectively nitrogen single breath washout (N2SBW) and nitrogen multiple breath washout (N2MBW), may be pathological in patients with clinical suspicion of asthma but normal spirometry. Our aim was to assess whether N2SBW and N2MBW are associated with methacholine challenge test (MCT) results in this population. We also postulated that an alteration in SIII at N2SBW could be detected before the 20% fall of forced expiratory volume in the first second (FEV1) in MCT.

STUDY DESIGN AND METHODS

This prospective, observational, single-centre study included patients with suspicion of asthma with normal spirometry. Patients completed questionnaires on symptoms and health-related quality-of-life and underwent the following lung function tests: N2SBW (SIII), N2MBW (Lung clearance index (LCI), Scond, Sacin), MCT (FEV1 and sGeff) as well as N2SBW between each methacholine dose.

RESULTS

182 patients were screened and 106 were included in the study, with mean age of 41.8±14 years. The majority were never-smokers (58%) and women (61%). MCT was abnormal in 48% of participants, N2SBW was pathological in 10.6% at baseline and N2MBW abnormality ranged widely (LCI 81%, Scond 18%, Sacin 43%). The dose response rate of the MCT showed weak to moderate correlation with the subsequent N2SBW measurements during the provocation phases (ρ 0.34-0.50) but no correlation with N2MBW.

CONCLUSIONS

Both MCT and N2 washout tests are frequently pathological in patients with suspicion of asthma with normal spirometry. The weak association and lack of concordance across the tests highlight that they reflect different but not interchangeable pathological pathways of the disease.

Validity and reliability of outcome measures to assess dysfunctional breathing: a systematic review

OBJECTIVE

This study aimed to systematically review the psychometric properties of outcome measures that assess dysfunctional breathing (DB) in adults.

METHODS

Studies on developing and evaluating measurement properties to assess DB were included. The study investigated the empirical research published between 1990 and February 2022, with an updated search in May 2023 in the Cochrane Library database of systematic reviews and the Cochrane Central Register of Controlled Trials, the Ovid Medline (full), the Ovid Excerta Medica Database, the Ovid allied and complementary medicines database, the Ebscohost Cumulative Index to Nursing and Allied Health Literature and the Physiotherapy Evidence Database. The included studies' methodological quality was assessed using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) risk of bias checklist. Data analysis and synthesis followed the COSMIN methodology for reviews of outcome measurement instruments.

RESULTS

Sixteen studies met the inclusion criteria, and 10 outcome measures were identified. The psychometric properties of these outcome measures were evaluated using COSMIN. The Nijmegen Questionnaire (NQ) is the only outcome measure with 'sufficient' ratings for content validity, internal consistency, reliability and construct validity. All other outcome measures did not report characteristics of content validity in the patients' group.

DISCUSSION

The NQ showed high-quality evidence for validity and reliability in assessing DB. Our review suggests that using NQ to evaluate DB in people with bronchial asthma and hyperventilation syndrome is helpful. Further evaluation of the psychometric properties is needed for the remaining outcome measures before considering them for clinical use.

PROSPERO REGISTRATION NUMBER

CRD42021274960.

Haemodynamic compensations for exercise tissue oxygenation in early stages of COPD: an integrated cardiorespiratory assessment study

BACKGROUND

Cardiovascular comorbidities are increasingly being recognised in early stages of chronic obstructive pulmonary disease (COPD) yet complete cardiorespiratory functional assessments of individuals with mild COPD or presenting with COPD risk factors are lacking. This paper reports on the effectiveness of the cardiocirculatory-limb muscles oxygen delivery and utilisation axis in smokers exhibiting no, or mild to moderate degrees of airflow obstruction using standardised cardiopulmonary exercise testing (CPET).

METHODS

Post-bronchodilator spirometry was used to classify participants as 'ever smokers without' (n=88), with 'mild' (n=63) or 'mild-moderate' COPD (n=56). All underwent CPET with continuous concurrent monitoring of oxygen uptake (V'O2) and of bioimpedance cardiac output (Qc) enabling computation of arteriovenous differences (a-vO2). Mean values of Qc and a-vO2 were mapped across set ranges of V'O2 and Qc isolines to allow for meaningful group comparisons, at same metabolic and circulatory requirements.

RESULTS

Peak exercise capacity was significantly reduced in the 'mild-moderate COPD' as compared with the two other groups who showed similar pulmonary function and exercise capacity. Self-reported cardiovascular and skeletal muscle comorbidities were not different between groups, yet disease impact and exercise intolerance scores were three times higher in the 'mild-moderate COPD' compared with the other groups. Mapping of exercise Qc and a-vO2 also showed a leftward shift of values in this group, indicative of a deficit in peripheral O2 extraction even for submaximal exercise demands. Concurrent with lung hyperinflation, a distinctive blunting of exercise stroke volume expansion was also observed in this group.

CONCLUSION

Contrary to the traditional view that cardiovascular complications were the hallmark of advanced disease, this study of early COPD spectrum showed a reduced exercise O2 delivery and utilisation in individuals meeting spirometry criteria for stage II COPD. These findings reinforce the preventive clinical management approach to preserve peripheral muscle circulatory and oxidative capacities.

Remote vision-based digital patient monitoring of pulse and respiratory rates in acute medical wards

Remote Vision-Based digital Patient Monitoring (VBPM) of pulse (PR) and respiratory rate (RR) was set up in six single rooms in an acute medical and an orthopaedic ward. We compared 102 PR and 154 RR VBPM measurements (from 27 patients) with paired routine nurse measurements. VBPM measurements of RR were validated by reviewing video footage. Nurse measurements of RR were often 16-18 breaths/minute, and did not match VBPM RR (overestimating at low RR and underestimating at high RR). Nurse measurements of pulse were on average 3.9 beats per minute greater than matched VBPM measurements. VBPM was unobtrusive and well accepted.

Comprehensive analysis of environmental exposure to hazardous trace elements and lung function: a national cross-sectional study

BACKGROUND

There is growing interest in the joint effects of hazardous trace elements (HTEs) on lung function deficits, but the data are limited. This is a critical research gap given increased global industrialisation.

METHODS

A national cross-sectional study including spirometry was performed among 2112 adults across 11 provinces in China between 2020 and 2021. A total of 27 HTEs were quantified from urine samples. Generalised linear models and quantile-based g-computation were used to explore the individual and joint effects of urinary HTEs on lung function, respectively.

RESULTS

Overall, there were negative associations between forced expiratory volume in 1 s (FEV1) and urinary arsenic (As) (z-score coefficient, -0.150; 95% CI, -0.262 to -0.038 per 1 ln-unit increase), barium (Ba) (-0.148, 95% CI: -0.258 to -0.039), cadmium (Cd) (-0.132, 95% CI: -0.236 to -0.028), thallium (Tl) (-0.137, 95% CI: -0.257 to -0.018), strontium (Sr) (-0.147, 95% CI: -0.273 to -0.022) and lead (Pb) (-0.121, 95% CI: -0.219 to -0.023). Similar results were observed for forced vital capacity (FVC) with urinary As, Ba and Pb and FEV1/FVC with titanium (Ti), As, Sr, Cd, Tl and Pb. We found borderline associations between the ln-quartile of joint HTEs and decreased FEV1 (-20 mL, 95% CI: -48 to +8) and FVC (-14 mL, 95% CI: -49 to+2). Ba and Ti were assigned the largest negative weights for FEV1 and FVC within the model, respectively.

CONCLUSION

Our study investigating a wide range of HTEs in a highly polluted setting suggests that higher urinary HTE concentrations are associated with lower lung function, especially for emerging Ti and Ba, which need to be monitored or regulated to improve lung health.

Predictive value of lung function measures for cardiovascular risk: a large prospective cohort study

INTRODUCTION

Although lung function measures are associated with cardiovascular disease (CVD), the added predictive values of these measures remain unclear.

METHODS

From the UK Biobank, 308 415 participants free of CVD with spirometry parameters were included. The CVD outcomes included were defined by QRISK3, the American College of Cardiology/American Heart Association (ACC/AHA) and the European Systematic Coronary Risk Evaluation (SCORE) prediction models, respectively. Cox proportional hazard models were used to estimate the associations of lung function measures with CVD outcomes. The predictive capability was determined by the decision curve analyses.

RESULTS

Over a median follow-up of 12.5 years, 21 885 QRISK3 events, 12 843 ACC/AHA events and 2987 SCORE events were recorded. The associations of spirometry parameters with CVD outcomes were L-shaped. Restrictive and obstructive impairments were associated with adjusted HRs of 1.84 (95% CI: 1.65 to 2.06) and 1.72 (95% CI: 1.55 to 1.90) for SCORE CVD, respectively, compared with normal spirometry. Similar associations were seen for QRISK3 CVD (restrictive vs normal, adjusted HR: 1.30, 95% CI: 1.25 to 1.36; obstructive vs normal, adjusted HR: 1.20, 95% CI: 1.15 to 1.25) and ACC/AHA CVD (restrictive vs normal, adjusted HR: 1.39, 95% CI: 1.31 to 1.47; obstructive vs normal, adjusted HR: 1.26, 95% CI: 1.19 to 1.33). Using models that integrated non-linear forced expiratory volume in 1 s led to additional 10-year net benefits per 100 000 persons of 25, 43 and 5 for QRISK3 CVD at the threshold of 10%, ACC/AHA CVD at 7.5% and SCORE CVD at 5.0%, respectively.

CONCLUSION

Clinicians could consider spirometry indicators in CVD risk assessment. Cost-effectiveness studies and clinical trials are needed to put new CVD risk assessment into practice.

Lung function tracking in children with perinatally acquired HIV following early antiretroviral therapy initiation

INTRODUCTION

Lung disease remains a frequent complication in children with perinatal HIV infection (CHIV) and exposure without infection (CHEU), resulting in diminished lung function. In CHIV, early antiretroviral therapy (ART) initiation improves survival and extrapulmonary outcomes. However, it is unknown if there is benefit to lung function.

METHODS

Cohorts of CHIV (ART initiated at median 4.0 months), CHEU and HIV-unexposed children (CHU) prospectively performed pulmonary function testing (PFT) consisting of spirometry, plethysmography and diffusing capacity from 2013 to 2020. We determined lung function trajectories for PFT outcomes comparing CHIV to CHU and CHEU to CHU, using linear mixed effects models with multiple imputation. Potential confounders included sex, age, height, weight, body mass index z-score, urine cotinine and Tanner stage.

RESULTS

328 participants (122 CHIV, 126 CHEU, 80 CHU) performed PFT (ages 6.6-15.6 years). Spirometry (forced expiratory volume in 1 s, FEV1, forced vital capacity (FVC), FEV1/FVC) outcomes were similar between groups. In plethysmography, the mean residual volume (RV) z-score was 17% greater in CHIV than CHU (95% CI 1% to 33%, p=0.042). There was no difference in total lung capacity (TLC) or RV/TLC z-scores between groups. Diffusing capacity for carbon monoxide was similar in all groups, while alveolar volume (VA) differed between HIV groups by sex.

CONCLUSION

Our study indicates that early ART initiation can mitigate the loss of lung function in CHIV with lasting benefit through childhood; however, there remains concern of small airway disease. CHEU does not appear to disrupt childhood lung function trajectory.

Defining the pathway to timely diagnosis and treatment of interstitial lung disease: a US Delphi survey

INTRODUCTION

Timely diagnosis of interstitial lung disease (ILD) is limited by obstacles in the current patient pathway. Misdiagnosis and delays are common and may lead to a significant burden of diagnostic procedures and worse outcomes. This Delphi survey aimed to identify consensus on the key steps that facilitate the patient journey to an accurate ILD diagnosis and appropriate management in the US.

METHODS

A modified Delphi analysis was conducted, comprising three online surveys based on a comprehensive literature search. The surveys spanned five domains (guidelines, community screening, diagnosis, management and specialist referral) and were completed by a panel of US physicians, including primary care physicians and pulmonologists practising in community or academic settings. A priori definitions of consensus agreement were median scores of 2-3 (agree strongly/agree), with an IQR of 0-1 for questions on a 7-point Likert scale from -3 to 3, or ≥80% agreement for binary questions.

RESULTS

Forty-nine panellists completed the surveys and 62 statements reached consensus agreement. There was consensus agreement on what should be included in the primary care evaluation of patients with suspected ILD and the next steps following workup. Regarding diagnosis in community pulmonology care, consensus agreement was reached on the requisition and reporting of high-resolution CT scans and the appropriate circumstances for holding multidisciplinary discussions. Additionally, there was consensus agreement on which symptoms and comorbidities should be monitored, the frequency of consultations and the assessment of disease progression. Regarding specialist referral, consensus agreement was reached on which patients should receive priority access to ILD centres and the contents of the referral package.

CONCLUSIONS

These findings clarify the most common issues that should merit further evaluation for ILD and help define the steps for timely, accurate diagnosis and appropriate collaborative specialty management of patients with ILD.

Association between serum high-density lipoprotein cholesterol and lung function in adults: three cross-sectional studies from US and Korea National Health and Nutrition Examination Survey

INTRODUCTION

Cholesterol is an irreplaceable nutrient in pulmonary metabolism; however, studies on high-density lipoprotein cholesterol (HDL-C) levels have shown conflicting results regarding lung function. Therefore, we investigated the association between lung function and HDL-C levels in three cross-sectional studies conducted in the USA and South Korea.

METHODS

US National Health and Nutrition Examination Survey (NHANES) III, US NHANES 2007-2012, and Korea National Health and Nutrition Examination Survey (KNHANES) IV-VII performed spirometry and met the American Thoracic Society recommendations. Multiple linear regression models were used to determine the relationship between serum lipid levels and lung function. The models were adjusted for age, sex, household income, body mass index, smoking pack year, use of lipid-lowering medication and race. Serum HDL-C levels were classified into three groups to assess the dose-response relationship according to the guideline from the National Cholesterol Education Program-Adult Treatment Panel III.

RESULTS

The adult participants of the KNHANES (n=31 288), NHANES III (n=12 182) and NHANES 2007-2012 (n=9122) were analysed. Multivariate linear regression analysis of the serum cholesterol profiles revealed that only serum HDL-C was associated with forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) in all three studies. A 1 SD increase in the HDL-C level increased the percent predicted FVC by 0.5%-1.5% p, and the per cent predicted FEV1 by 0.5%-1.7% p. In terms of HDL-C levels, correlations between the HDL-C groups and the per cent predicted FVC and FEV1 showed dose-response relationships. Compared with the normal group, high HDL-C levels increased FVC by 0.75%-1.79% p and FEV1 by 0.55%-1.90% p, while low levels led to 0.74%-2.19% p and 0.86%-2.68% p reductions in FVC and FEV1, respectively. Subgroup analyses revealed weaker associations in females from KNHANES and NHANES III.

CONCLUSION

In the three nationwide cross-sectional studies, high HDL-C levels were associated with improved FVC and FEV1. However, future studies are needed to confirm this correlation and elucidate the underlying mechanisms.

Bagasse dust exposure and chronic respiratory symptoms among workers in the Metehara and Wonji sugar factories in Ethiopia: a longitudinal study design

BACKGROUND

Ethiopia's sugar factories are growing by creating job opportunities for thousands of workers with varying educational, professional and socioeconomic backgrounds. These sugar factories are a source of several hazards that severely harm the workers' health. In this context, there is inconclusive evidence on the level of bagasse dust exposure and chronic respiratory health symptoms. This study aimed to assess the degree of bagasse dust exposure and chronic respiratory health symptoms.

METHODS

In this longitudinal study, five workstations were selected for dust sampling. A stratified random sampling technique was used to select 1043 participants. We measured the dust intensity using a calibrated handheld real-time dust monitor once a month for 5 months, totalling 50 dust samples. Chronic respiratory symptoms were assessed using the American Thoracic Society's respiratory symptoms questionnaire.

RESULTS

A 1 hour time-weighted average of bagasse dust intensity in the boiler, power turbine and evaporation plant was 8.93 mg/m3, 8.88 mg/m3 and 8.68 mg/m3, respectively. This corresponded to an exposure level to bagasse dust of 85.52% (95% CI 83.2% to 87.6%). The level of chronic respiratory health symptoms was 60.6% (95% CI 59.2% to 61.9%). The most common respiratory symptoms were wheezing (96.8%), coughing (89.7%) and breathlessness (80.9%). The identified risk factors were lack of dust control technology (β= 0.64, 95% CI 0.53 to 0.75), not practising wet spray (β = 0.27, 95% CI 0.21 to 0.41) and not wearing proper respiratory protection devices (β = 0.12, 95% CI 0.30 to 0.56).

CONCLUSIONS

Bagasse dust exposure and respiratory health abnormalities were worrying concerns. The absence of dust control technologies and no practice of wet spraying elevated the level of exposure. Not wearing proper respiratory protection gear increased the odds of having respiratory abnormalities. Hence, the use of mechanical solutions to stop dust emissions at their sources and the wearing of proper respiratory protection gear are highly advised.

Bisoprolol versus celiprolol on dynamic hyperinflation, cardiopulmonary exercise and domiciliary safety in COPD: a single-centre, randomised, crossover study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is frequently associated with cardiovascular disease. The utility of beta-blockers for treating patients with COPD may be beneficial, but their safety remains uncertain, including worsening of dynamic hyperinflation (DH) during exercise. We hypothesised that among cardioselective beta-blockers celiprolol, due to its partial beta-2 agonist activity, may be safer than bisoprolol on exercise DH.

METHODS

We measured isotime inspiratory capacity (IC) during cycle endurance testing in eleven moderate-severe COPD subjects, alongside other non-invasive cardiopulmonary exercise, bioreactance cardiac output, pulmonary function, biomarkers and daily domiciliary measures. Participants received titrated doses of either bisoprolol (maximim 5 mg) or celiprolol (maximum 400 mg) in randomised crossover fashion, each over 4 weeks.

RESULTS

Clinically relevant DH occurred between resting and exercise isotime IC but showed no significant difference with either beta-blocker compared with post-run-in pooled baseline or between treatments. There were no other significant differences observed for remaining exercise ventilatory; non-invasive cardiac output; resting pulmonary function; beta-2 receptor and cardiac biomarkers; domiciliary pulmonary function, oxygen saturation and symptom outcomes, either between treatments or compared with baseline. No significant adverse effects occurred.

CONCLUSIONS

Significant DH in moderate-severe COPD subjects was no different between bisoprolol or celiprolol or versus baseline. A broad spectrum of other non-invasive cardiopulmonary and domiciliary safety outcomes was equally reassuring. Bronchoprotection with a concomitant long-acting muscarinic antagonist might be an important safety measure in this context.

TRIAL REGISTRATION NUMBER

NCT02380053.

The 'ABC' of respiratory disorders among adult Indigenous people: asthma, bronchiectasis and COPD among Aboriginal Australians - a systematic review

BACKGROUND

Aboriginal Australians are reported to have higher presence of chronic respiratory diseases. However, comprehensive evidence surrounding this is sparse. Hence, a systematic review was undertaken to appraise the current state of knowledge on respiratory health in the adult Aboriginal Australians, in particular among the three most common respiratory disorders: asthma, bronchiectasis and chronic obstructive pulmonary disease (COPD).

METHODS

A systematic review of primary literature published between January 2012 and October 2022, using the databases PubMed and Scopus, was conducted. Studies were included if they reported adult Aboriginal Australian prevalence's or outcomes related to asthma, bronchiectasis or COPD, and excluded if adult data were not reported separately, if Aboriginal Australian data were not reported separately or if respiratory disorders were combined into a single group. Risk of bias was assessed by both Joanne Briggs Institute checklists and Hoys' bias assessment. Summary data pertaining to prevalence, lung function, symptoms, sputum cultures and mortality for each of asthma, bronchiectasis and COPD were extracted from the included studies.

RESULTS

Thirty-seven studies were included, involving approximately 33 364 participants (71% female). Eighteen studies reported on asthma, 21 on bronchiectasis and 30 on COPD. The majority of studies (94%) involved patients from hospitals or respiratory clinics and were retrospective in nature. Across studies, the estimated prevalence of asthma was 15.4%, bronchiectasis was 9.4% and COPD was 13.7%, although there was significant geographical variation. Only a minority of studies reported on clinical manifestations (n=7) or symptoms (n=4), and studies reporting on lung function parameters (n=17) showed significant impairment, in particular among those with concurrent bronchiectasis and COPD. Airway exacerbation frequency and hospital admission rates including mortality are high.

DISCUSSION

Although risk of bias globally was assessed as low, and study quality as high, there was limited diversity of studies with most reporting on referred populations, and the majority originating from two centres in the Northern Territory. The states with the greatest Aboriginal Australian population (Victoria and New South Wales) reported the lowest number of studies and patients. This limits the generalisability of results to the wider Aboriginal Australian population due to significant environmental, cultural and socioeconomic variation across the population. Regardless, Aboriginal Australians appear to display a high prevalence, alongside quite advanced and complex chronic respiratory diseases. There is however significant heterogeneity of prevalence, risk factors and outcomes geographically and by patient population. Further collaborative efforts are required to address specific diagnostic and management pathways in order to close the health gap secondary to respiratory disorders in this population.

Comparison of mathematically arterialised venous blood gas sampling with arterial, capillary, and venous sampling in adult patients with hypercapnic respiratory failure: a single-centre longitudinal cohort study

BACKGROUND

Accurate arterial blood gas (ABG) analysis is essential in the management of patients with hypercapnic respiratory failure, but repeated sampling requires technical expertise and is painful. Missed sampling is common and has a negative impact on patient care. A newer venous to arterial conversion method (v-TAC, Roche) uses mathematical models of acid-base chemistry, a venous blood gas sample and peripheral blood oxygen saturation to calculate arterial acid-base status. It has the potential to replace routine ABG sampling for selected patient cohorts. The aim of this study was to compare v-TAC with ABG, capillary and venous sampling in a patient cohort referred to start non-invasive ventilation (NIV).

METHODS

Recruited patients underwent near simultaneous ABG, capillary blood gas (CBG) and venous blood gas (VBG) sampling at day 0, and up to two further occasions (day 1 NIV and discharge). The primary outcome was the reliability of v-TAC sampling compared with ABG, via Bland-Altman analysis, to identify respiratory failure (via PaCO₂) and to detect changes in PaCO₂ in response to NIV. Secondary outcomes included agreements with pH, sampling success rates and pain.

RESULTS

The agreement between ABG and v-TAC/venous PaCO₂ was assessed for 119 matched sampling episodes and 105 between ABG and CBG. Close agreement was shown for v-TAC (mean difference (SD) 0.01 (0.5) kPa), but not for CBG (-0.75 (0.69) kPa) or VBG (+1.00 (0.90) kPa). Longitudinal data for 32 patients started on NIV showed the closest agreement for ABG and v-TAC (R²=0.61). v-TAC sampling had the highest first-time success rate (88%) and was less painful than arterial (p<0.0001).

CONCLUSION

Mathematical arterialisation of venous samples was easier to obtain and less painful than ABG sampling. Results showed close agreement for PaCO2 and pH and tracked well longitudinally such that the v-TAC method could replace routine ABG testing to recognise and monitor patients with hypercapnic respiratory failure.

TRIAL REGISTRATION NUMBER

NCT04072848; www.

CLINICALTRIALS

gov.

Feasibility of dynamic chest radiography to calculate lung volumes in adult people with cystic fibrosis: a pilot study

INTRODUCTION

Dynamic chest radiography (DCR) is a novel, low-dose, real-time digital imaging system where software identifies moving thoracic structures and can automatically calculate lung areas. In an observational, prospective, non-controlled, single-centre pilot study, we compared it with whole-body plethysmography (WBP) in the measurement of lung volume subdivisions in people with cystic fibrosis (pwCF).

METHODS

Lung volume subdivisions were estimated by DCR using projected lung area (PLA) during deep inspiration, tidal breathing and full expiration, and compared with same-day WBP in 20 adult pwCF attending routine review. Linear regression models to predict lung volumes from PLA were developed.

RESULTS

Total lung area (PLA at maximum inspiration) correlated with total lung capacity (TLC) (r=0.78, p<0.001), functional residual lung area with functional residual capacity (FRC) (r=0.91, p<0.001), residual lung area with residual volume (RV) (r=0.82, p=0.001) and inspiratory lung area with inspiratory capacity (r=0.72, p=0.001). Despite the small sample size, accurate models were developed for predicting TLC, RV and FRC.

CONCLUSION

DCR is a promising new technology that can be used to estimate lung volume subdivisions. Plausible correlations between plethysmographic lung volumes and DCR lung areas were identified. Further studies are needed to build on this exploratory work in both pwCF and individuals without CF.

TRIAL REGISTRATION NUMBER

ISRCTN64994816.

Lung function and cognitive ability in children: a UK birth cohort study

BACKGROUND

Decreased adult lung function is associated with subsequent impairment in cognition. A similar relationship in early life could be of great policy importance, since childhood cognitive ability determines key adult outcomes, including socioeconomic status and mortality. We aimed to expand the very limited data available on this relationship in children, and hypothesised that reduced lung function would be longitudinally associated with decreased cognitive ability.

METHODS

Lung function was measured at age 8 (forced expiratory volume in one second (FEV₁), forced vital capacity (FVC); % predicted), and cognitive ability was measured at ages 8 (Wechsler Intelligence Scale for Children, third edition) and 15 (Wechsler Abbreviated Scale of Intelligence), in the Avon Longitudinal Study of Parents and Children. Potential confounders were identified as preterm birth, birth weight, breastfeeding duration, prenatal maternal smoking, childhood environmental tobacco smoke exposure, socioeconomic status and prenatal/childhood air pollution exposure. Univariable and multivariable linear models (n range=2332-6672) were fitted to assess the cross-sectional and longitudinal associations of lung function with cognitive ability, and change in cognitive ability between ages 8 and 15.

RESULTS

In univariate analyses, both FEV₁ and FVC at age 8 were associated with cognitive ability at both ages, but after adjustment, only FVC was associated with full-scale IQ (FSIQ) at ages 8 (β=0.09 (95% CI 0.05 to 0.12; p<0.001)) and 15 (β=0.06 (0.03 to 0.10; p=0.001)). We did not find evidence of an association between either lung function parameter and interval change in standardised FSIQ.

DISCUSSION

Reduced FVC, but not FEV₁, is independently associated with decreased cognitive ability in children. This low-magnitude association attenuates between ages 8 and 15, while no association is evident with longitudinal change in cognitive ability. Our results support a link between FVC and cognition across the life course, possibly due to shared genetic or environmental risk, rather than causation.

Pulmonary sequelae in 2-year-old children after hospitalisation for respiratory syncytial virus lower respiratory tract infection during infancy: an observational study

BACKGROUND

Respiratory syncytial virus (RSV) is the most common cause of hospitalisation for lower respiratory tract infection (LRTI) in children. RSV LRTI during early childhood may increase susceptibility to recurrent wheezing and asthma.

RESEARCH QUESTION

The aim of this study was to describe the pulmonary sequelae at 1 and 2 years of age following RSV LRTI hospitalisation during the first year of life in term infants.

STUDY DESIGN AND METHODS

A longitudinal case-control study was undertaken from April 2016 to December 2019. Cases constituted children hospitalised with PCR-confirmed RSV LRTI during infancy and controls were children not previously hospitalised with LRTI. A questionnaire detailing environmental and medical history, as well as a modified International Study of Asthma and Allergies (ISAAC) questionnaire, was administered, and pulmonary function testing, including oscillometry, tidal breath flow-volume loops and multiple breath wash-out, was performed, at one and two years of age.

RESULTS

One (n=308) and two-year-old (n=214) cases were more likely than one (n=292) and two-year-old (n=209) controls to have experienced clinical pulmonary symptoms, including wheezing ((55% vs 24%; p<0.001) and (61% vs 16%; p<0.001)), received treatment for wheezing ((17 vs 8%; p<0.001) and (51 vs 6%; p<0.001)) and had any admissions for wheezing ((31 vs 6%; p<0.001) and (46 vs 1.4%; p<0.001)) or any LRTI ((24 vs 2%; p<0.001) and (32 vs 1.4%; p<0.001)), after the initial RSV hospitalisation. RSV LRTI during infancy was associated with an increase in airway resistance by two years (22.46 vs 20.76 hPa.s.l^-1 (p=0.022)), along with a decrease in compliance at both one (-4.61 vs -3.09 hPa.s/l (p<0.001)) and two years (-0.99 vs 0.33 hPa.s/l¹ (p<0.001)). There was an increased work of breathing at one year, but this was no longer present at two years.

INTERPRETATION

RSV LRTI during infancy in cases was associated with more clinical and pulmonary function sequelae through to two years of age.

Evaluation of clinically relevant changes in the lung clearance index in children with cystic fibrosis and healthy controls

BACKGROUND

The limits of reproducibility of the lung clearance index (LCI) are higher in children with cystic fibrosis (CF) compared with healthy children, and it is currently unclear what defines a clinically meaningful change.

METHODS

In a prospective multisite observational study of children with CF and healthy controls (HCs), we measured LCI, FEV₁% predicted and symptom scores at quarterly visits over 2 years. Two reviewers performed a detailed review of visits to evaluate the frequency that between visit LCI changes outside ±10%, ±15%, ±20% represented a clinically relevant signal. In the setting of acute respiratory symptoms, we used a generalised estimating equation model, with a logit link function to determine the ability of LCI worsening at different thresholds to predict failure of lung function recovery at follow-up.

RESULTS

Clinically relevant LCI changes outside ±10%, ±15% and ±20% were observed at 25.7%, 15.0% and 8.3% of CF visits (n=744), respectively. The proportions of LCI changes categorised as noise, reflecting biological variability, were comparable between CF and HC at the 10% (CF 9.9% vs HC 13.0%), 15% (CF 4.3% vs HC 3.1%) and 20% (CF 2.4% vs HC 1.0%) thresholds. Compared with symptomatic CF visits without a worsening in LCI, events with ≥10% LCI increase were more likely to fail to recover baseline LCI at follow-up.

CONCLUSION

The limits of reproducibility of the LCI in healthy children can be used to detect clinically relevant changes and thus inform clinical care in children with CF.

Faster lung function decline in people living with HIV despite adequate treatment: a longitudinal matched cohort study

INTRODUCTION

Chronic lung disease is common among people living with HIV (PLWH). We hypothesised that PLWH receiving antiretroviral therapy (ART) have faster lung function decline than matched controls.

METHODS

We performed a prospective matched cohort study by including ART-treated PLWH from the Copenhagen Co-morbidity in HIV Infection Study (n=705) and the INSIGHT Strategic Timing of Antiretroviral Treatment Pulmonary Substudy (n=425) and frequency matched population controls from the Copenhagen General Population Study (n=2895) in a 1:3 ratio. Eligible participants were ≥25 years old and had two spirometry tests separated by at least 2 years of follow-up. Forced expiratory volume in 1 s (FEV₁) decline (mL/year) was compared between PLWH and controls using a linear mixed model adjusted for age, sex, ethnicity and smoking status. Effect modification by smoking was investigated in subgroup analyses.

RESULTS

The majority of PLWH were virally suppressed (96.1%). The adjusted mean annual decline in FEV₁ was faster in PLWH than in controls with 36.4 (95% CI 33.7 to 39.1) vs 27.9 (95% CI 26.9 to 28.8) mL/year, yielding a difference of 8.5 (95% CI 5.6 to 11.4) mL/year. The association between HIV and FEV₁ decline was modified by smoking, with the largest difference in current smokers (difference: 16.8 (95% CI 10.5 to 23.0) mL/year) and the smallest difference in never-smokers (difference: 5.0 (95% CI 0.7 to 9.3) mL/year). FEV₁ decline >40 mL/year was more prevalent in PLWH (adjusted OR: 1.98 (95% CI 1.67 to 2.34)).

CONCLUSION

Well-treated PLWH have faster lung function decline than controls and smoking seems to modify this association, suggesting that smoking may lead to more rapid lung function decline in PLWH than in controls.

Pleural and transpulmonary pressures to tailor protective ventilation in children

This review aims to: (1) describe the rationale of pleural (P_PL) and transpulmonary (P_L) pressure measurements in children during mechanical ventilation (MV); (2) discuss its usefulness and limitations as a guide for protective MV; (3) propose future directions for paediatric research. We conducted a scoping review on P_L in critically ill children using PubMed and Embase search engines. We included peer-reviewed studies using oesophageal (P_ES) and P_L measurements in the paediatric intensive care unit (PICU) published until September 2021, and excluded studies in neonates and patients treated with non-invasive ventilation. P_L corresponds to the difference between airway pressure and P_PL Oesophageal manometry allows measurement of P_ES, a good surrogate of P_PL, to estimate P_L directly at the bedside. Lung stress is the P_L, while strain corresponds to the lung deformation induced by the changing volume during insufflation. Lung stress and strain are the main determinants of MV-related injuries with P_L and P_PL being key components. P_L-targeted therapies allow tailoring of MV: (1) Positive end-expiratory pressure (PEEP) titration based on end-expiratory P_L (direct measurement) may be used to avoid lung collapse in the lung surrounding the oesophagus. The clinical benefit of such strategy has not been demonstrated yet. This approach should consider the degree of recruitable lung, and may be limited to patients in which PEEP is set to achieve an end-expiratory P_L value close to zero; (2) Protective ventilation based on end-inspiratory P_L (derived from the ratio of lung and respiratory system elastances), might be used to limit overdistention and volutrauma by targeting lung stress values < 20-25 cmH₂O; (3) P_PL may be set to target a physiological respiratory effort in order to avoid both self-induced lung injury and ventilator-induced diaphragm dysfunction; (4) P_PL or P_L measurements may contribute to a better understanding of cardiopulmonary interactions. The growing cardiorespiratory system makes children theoretically more susceptible to atelectrauma, myotrauma and right ventricle failure. In children with acute respiratory distress, P_PL and P_L measurements may help to characterise how changes in PEEP affect P_PL and potentially haemodynamics. In the PICU, P_PL measurement to estimate respiratory effort is useful during weaning and ventilator liberation. Finally, the use of P_PL tracings may improve the detection of patient ventilator asynchronies, which are frequent in children. Despite these numerous theoritcal benefits in children, P_ES measurement is rarely performed in routine paediatric practice. While the lack of robust clincal data partially explains this observation, important limitations of the existing methods to estimate P_PL in children, such as their invasiveness and technical limitations, associated with the lack of reference values for lung and chest wall elastances may also play a role. P_PL and P_L monitoring have numerous potential clinical applications in the PICU to tailor protective MV, but its usefulness is counterbalanced by technical limitations. Paediatric evidence seems currently too weak to consider oesophageal manometry as a routine respiratory monitoring. The development and validation of a noninvasive estimation of P_L and multimodal respiratory monitoring may be worth to be evaluated in the future.

Disease monitoring using lung function trajectory in lymphangioleiomyomatosis: assessment in two national cohorts

STUDY QUESTION

In lymphangioleiomyomatosis, airflow obstruction and impairment of gas transfer progress at variable rates and serial lung function is recommended for disease monitoring. As these measurements are variable, recognising subjects needing treatment can be difficult. We used two prospective national cohorts to study change over time and variation in FEV₁ to inform clinical decision making.

PATIENTS AND METHODS

Clinical and lung function data for 141 UK and 148 American subjects were studied. Multilevel mixed effects modelling, route mean square analysis of errors and Bland-Altman analysis were used to analyse variability in lung function over time.

RESULTS

At baseline assessment, DL_CO was reduced to a greater degree than FEV₁. In untreated patients, FEV₁ and DL_CO declined at proportionately similar rates independent of initial lung function. In mechanistic target of rapamycin (mTOR) inhibitor treated patients, FEV₁ stabilised but DL_CO continued to decline. FEV₁/DL_CO per cent predicted ratio was 1.37 (0.43) at baseline and increased to 1.41 (0.50) after 42 (24) months (p=0.0002). At least five measurements were required before >70% of individuals had estimates of rate of FEV₁ loss within 50 mL/year and DL_CO loss within 0.1 mmol/min/kPa/year of the final values.

CONCLUSIONS

While FEV₁ and DL_CO fall proportionately in most, in early disease and during mTOR inhibitor treatment, DL_CO should also be monitored as it may fall independent of FEV₁. Since at least five observations over many months are required to make confident estimates of FEV₁ and DL_CO trajectories, new strategies are needed to measure disease activity and target early treatment appropriately.

Deep learning using multilayer perception improves the diagnostic acumen of spirometry: a single-centre Canadian study

RATIONALE

Spirometry and plethysmography are the gold standard pulmonary function tests (PFT) for diagnosis and management of lung disease. Due to the inaccessibility of plethysmography, spirometry is often used alone but this leads to missed or misdiagnoses as spirometry cannot identify restrictive disease without plethysmography. We aimed to develop a deep learning model to improve interpretation of spirometry alone.

METHODS

We built a multilayer perceptron model using full PFTs from 748 patients, interpreted according to international guidelines. Inputs included spirometry (forced vital capacity, forced expiratory volume in 1 s, forced mid-expiratory flow_25-75), plethysmography (total lung capacity, residual volume) and biometrics (sex, age, height). The model was developed with 2582 PFTs from 477 patients, randomly divided into training (80%), validation (10%) and test (10%) sets, and refined using 1245 previously unseen PFTs from 271 patients, split 50/50 as validation (136 patients) and test (135 patients) sets. Only one test per patient was used for each of 10 experiments conducted for each input combination. The final model was compared with interpretation of 82 spirometry tests by 6 trained pulmonologists and a decision tree.

RESULTS

Accuracies from the first 477 patients were similar when inputs included biometrics+spirometry+plethysmography (95%±3%) vs biometrics+spirometry (90%±2%). Model refinement with the next 271 patients improved accuracies with biometrics+pirometry (95%±2%) but no change for biometrics+spirometry+plethysmography (95%±2%). The final model significantly outperformed (94.67%±2.63%, p<0.01 for both) interpretation of 82 spirometry tests by the decision tree (75.61%±0.00%) and pulmonologists (66.67%±14.63%).

CONCLUSIONS

Deep learning improves the diagnostic acumen of spirometry and classifies lung physiology better than pulmonologists with accuracies comparable to full PFTs.

Respiratory function and CT abnormalities among survivors of COVID-19 pneumonia: a nationwide follow-up study

INTRODUCTION

Considering the pulmonary burden caused by acute COVID-19, questions remain of respiratory consequences after recovery. The aim of the study was to describe respiratory function of COVID-19 pneumonia survivors at mid-term follow-up (median 68 days) and assess whether impairments were predicted by acute illness severity or residual CT abnormalities.

METHODS

Residents of Iceland that had COVID-19 and oxygen saturation ≤94% from 28 February 2020 to 30 April 2021 were offered a clinical follow-up visit with an interview, a 6 min walk test (6MWT), spirometry with gas exchange measurement and chest CT. The results of these examinations were described, grouped by the level of care during acute illness. The associations of disease severity and CT abnormalities at follow-up with subjective dyspnoea, 6MWT results and lung function test results were estimated with regression analyses.

RESULTS

Of 190 eligible patients, 164 (86%) participated in the study. Of those, 32 had never been admitted to hospital, 103 were admitted to hospital without intensive care and 29 had required intensive care. At a follow-up, need for intensive care during acute illness was associated with shorter walking distance on 6MWT, lower oxygen saturation and lower DL_CO. Imaging abnormalities at follow-up were observed for most participants (74%) and the magnitude of these changes was associated with decrements in 6MWT distance, oxygen saturation, forced vital capacity and DL_CO.

CONCLUSIONS

The findings show that impaired exercise capacity and lung physiology at follow-up were primarily observed for patients with COVID-19 pneumonia that required intensive care treatment and/or had persistent imaging abnormalities.

Small airway function measured using forced expiratory flow between 25% and 75% of vital capacity and its relationship to airflow limitation in symptomatic ever-smokers: a cross-sectional study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is diagnosed and its severity graded by traditional spirometric parameters (forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) and FEV₁, respectively) but these parameters are considered insensitive for identifying early pathology. Measures of small airway function, including forced expiratory flow between 25% and 75% of vital capacity (FEF_25-75), may be more valuable in the earliest phases of COPD. This study aimed to determine the prevalence of low FEF_25-75 in ever-smokers with and without airflow limitation (AL) and to determine whether FEF_25-75 relates to AL severity.

METHOD

A retrospective analysis of lung function data of 1458 ever-smokers suspected clinically of having COPD. Low FEF_25-75 was defined by z-score<-0.8345 and AL was defined by FEV₁/FVC z-scores<-1.645. The severity of AL was evaluated using FEV₁ z-scores. Participants were placed into three groups: normal FEF_25-75/ no AL (normal FEF_25-75/AL-); low FEF_25-75/ no AL (low FEF_25-75/AL-) and low FEF_25-75/ AL (low FEF_25-75/AL+).

RESULTS

Low FEF_25-75 was present in 99.9% of patients with AL, and 50% of those without AL. Patients in the low FEF_25-75/AL- group had lower spirometric measures (including FEV₁ FEF_25-75/FVC and FEV₃/FVC) than those in the normal FEF_25-75/AL- group. FEF_25-75 decreased with AL severity. A logistic regression model demonstrated that in the absence of AL, the presence of low FEF_25-75 was associated with lower FEV₁ and FEV₁/FVC even when smoking history was accounted for.

CONCLUSIONS

Low FEF_25-75 is a physiological trait in patients with conventional spirometric AL and likely reflects early evidence of impairment in the small airways when spirometry is within the 'normal range'. FEF_25-75 likely identifies a group of patients with early evidence of pathological lung damage who warrant careful monitoring and reinforced early intervention to abrogate further lung injury.

Predictive value of prebronchodilator and postbronchodilator spirometry for COPD features and outcomes

Introduction

We compared the predictive value of prebronchodilator and postbronchodilator spirometry for chronic obstructive pulmonary disease (COPD) features and outcomes.

Methods

We analysed COPDGene data of 10 192 subjects with smoking history. We created regressions models with the following dependent variables: clinical, functional and radiographic features, and the following independent variables: prebronchodilator airflow obstruction (PREO) and postbronchodilator airflow obstruction (POSTO), prebronchodilator and postbronchodilator FEV₁% predicted. We compared the model performance using the Akaike information criterion (AIC).

Results

The COPD prevalence was higher using PREO. About 8.5% had PREO but no airflow obstruction in postbronchodilator spirometry (POSTN) (PREO-POSTN) and 3% of all subjects had no aiflow obstruction in prebronchodilator spirometry (PREN) but POSTO (PREN-POSTO). We found no difference in COPD features and outcomes between PREO-POSTN and PREN-POSTO subjects. Although, both prebronchodilator and postbronchodilator spirometries are both associated with chronic bronchitis, dyspnoea, exercise capacity and COPD radiographic findings, models that included postbronchodilator spirometric measures performed better than models with prebronchodilator measures to predict these COPD features. The predictive value of prebronchodilator and postbronchodilator spirometries for respiratory exacerbations, change in forced expiratory volume in 1 s, dyspnoea and exercise capacity during a 5-year period is relatively similar, but postbronchodilator spirometric measures are better predictors of mortality based on AIC.

Conclusions

Postbronchodilator spirometry may be a more accurate predictor of COPD features and outcomes.

The quantitative link of lung clearance index to bronchial segments affected by bronchiectasis

In adult patients with cystic fibrosis (CF), the lung clearance index (LCI) derived from the multiple breath washout relates to both acinar and conductive ventilation heterogeneity. The latter component predicts an association between LCI and the number of bronchial segments affected by bronchiectasis. Here, we experimentally demonstrated this association in patients with CF, and also examined an ancillary group of patients with non-CF bronchiectasis. We conclude that lung disease severity in terms of number of bronchial segments results in an associated LCI increase, likely constituting a portion of LCI that cannot be reversed by treatment in patients with CF lung disease.

Raw milk consumption and other early-life farm exposures and adult pulmonary function in the Agricultural Lung Health Study

Literature suggests that early exposure to the farming environment protects against atopy and asthma; few studies have examined pulmonary function. We evaluated associations between early-life farming exposures and pulmonary function in 3061 adults (mean age=63) from a US farming population using linear regression. Childhood raw milk consumption was associated with higher FEV₁ (β=49.5 mL, 95% CI 2.8 to 96.1 mL, p=0.04) and FVC (β=66.2 mL, 95% CI 13.2 to 119.1 mL, p=0.01). We did not find appreciable associations with other early-life farming exposures. We report a novel association between raw milk consumption and higher pulmonary function that lasts into older adulthood.

Breathing-swallowing discoordination is associated with frequent exacerbations of COPD

Introduction

Impaired coordination between breathing and swallowing (breathing–swallowing discoordination) may be a significant risk factor for the exacerbation of chronic obstructive pulmonary disease (COPD). We examined breathing–swallowing discoordination in patients with COPD using a non-invasive and quantitative technique and determined its association with COPD exacerbation.

Methods

We recruited 65 stable outpatients with COPD who were enrolled in our prospective observational cohort study and did not manifest an apparent swallowing disorder. COPD exacerbation was monitored for 1 year before and 1 year after recruitment. Swallowing during inspiration (the I-SW pattern) and swallowing immediately followed by inspiration (the SW-I pattern) were identified.

Results

The mean frequency of the I-SW and/or SW-I patterns (I-SW/SW-I rate) was 21.5%±25.5%. During the 2-year observation period, 48 exacerbation incidents (25 patients) were identified. The I-SW/SW-I rate was significantly associated with the frequency of exacerbation. During the year following recruitment, patients with a higher I-SW/SW-I frequency using thicker test foods exhibited a significantly higher probability of future exacerbations (p=0.002, log-rank test).

Conclusions

Breathing–swallowing discoordination is strongly associated with frequent exacerbations of COPD. Strategies that identify and improve breathing–swallowing coordination may be a new therapeutic treatment for patients with COPD.

Sound: a non-invasive measure of cough intensity

Introduction

Cough intensity is an important determinant of cough severity reported by patients. Cough sound analysis has been widely validated for the measurement of cough frequency but few studies have validated its use in the assessment of cough strength. We investigated the relationship between cough sound and physiological measures of cough strength.

Methods

32 patients with chronic cough and controls underwent contemporaneous measurements of voluntary cough sound, flow and oesophageal pressure. Sound power, peak energy, rise-time, duration, peak-frequency, bandwidth and centroid-frequency were assessed and compared with physiological measures. The relationship between sound and subjective cough strength Visual Analogue Score (VAS), the repeatability of cough sounds and the effect of microphone position were also assessed.

Results

Sound power and energy correlated strongly with cough flow (median Spearman’s r=0.87–0.88) and oesophageal pressure (median Spearman’s r=0.89). Sound power and energy correlated strongly with cough strength VAS (median Spearman’s r=0.84–0.86) and were highly repeatable (intraclass correlation coefficient=0.93–0.94) but both were affected by change in microphone position.

Conclusions

Cough sound power and energy correlate strongly with physiological measures and subjective perception of cough strength. Power and energy are highly repeatable measures but the microphone position should be standardised. Our findings support the use of cough sound as an index of cough strength.

Determinants of early-life lung function in African infants

BACKGROUND

Low lung function in early life is associated with later respiratory illness. There is limited data on lung function in African infants despite a high prevalence of respiratory disease.

AIM

To assess the determinants of early lung function in African infants.

METHOD

Infants enrolled in a South African birth cohort, the Drakenstein child health study, had lung function measured at 6-10 weeks of age. Measurements, made with the infant breathing via a facemask during natural sleep, included tidal breathing, sulfur hexafluoride multiple breath washout and the forced oscillation technique. Information on antenatal and early postnatal exposures was collected using questionnaires and urine cotinine. Household benzene exposure was measured antenatally.

RESULTS

Successful tests were obtained in 645/675 (95%) infants, median (IQR) age of 51 (46-58) days. Infant size, age and male gender were associated with larger tidal volume. Infants whose mothers smoked had lower tidal volumes (-1.6 mL (95% CI -3.0 to -0.1), p=0.04) and higher lung clearance index (0.1 turnovers (95% CI 0.01 to 0.3), p=0.03) compared with infants unexposed to tobacco smoke. Infants exposed to alcohol in utero or household benzene had lower time to peak tidal expiratory flow over total expiratory time ratios, 10% (95% CI -15.4% to -3.7%), p=0.002) and 3.0% (95% CI -5.2% to -0.7%, p=0.01) lower respectively compared with unexposed infants. HIV-exposed infants had higher tidal volumes (1.7 mL (95% CI 0.06 to 3.3) p=0.04) compared with infants whose mothers were HIV negative.

CONCLUSION

We identified several factors including infant size, sex, maternal smoking, maternal alcohol, maternal HIV and household benzene associated with altered early lung function, many of which are factors amenable to public health interventions. Long-term study of lung function and respiratory disease in these children is a priority to develop strategies to strengthen child health.

Genetic variants affecting cross-sectional lung function in adults show little or no effect on longitudinal lung function decline

BACKGROUND

Genome-wide association studies have identified numerous genetic regions that influence cross-sectional lung function. Longitudinal decline in lung function also includes a heritable component but the genetic determinants have yet to be defined.

OBJECTIVES

We aimed to determine whether regions associated with cross-sectional lung function were also associated with longitudinal decline and to seek novel variants which influence decline.

METHODS

We analysed genome-wide data from 4167 individuals from the Busselton Health Study cohort, who had undergone spirometry (12 695 observations across eight time points). A mixed model was fitted and weighted risk scores were calculated for the joint effect of 26 known regions on baseline and longitudinal changes in FEV₁ and FEV₁/FVC. Potential additional regions of interest were identified and followed up in two independent cohorts.

RESULTS

The 26 regions previously associated with cross-sectional lung function jointly showed a strong effect on baseline lung function (p=4.44×10^-16 for FEV₁/FVC) but no effect on longitudinal decline (p=0.160 for FEV₁/FVC). This was replicated in an independent cohort. 39 additional regions of interest (48 variants) were identified; these associations were not replicated in two further cohorts.

CONCLUSIONS

Previously identified genetic variants jointly have a strong effect on cross-sectional lung function in adults but little or no effect on the rate of decline of lung function. It is possible that they influence COPD risk through lung development. Although no genetic variants have yet been associated with lung function decline at stringent genome-wide significance, longitudinal change in lung function is heritable suggesting that there is scope for future discoveries.

Choking on a foreign body: a physiological study of the effectiveness of abdominal thrust manoeuvres to increase thoracic pressure

The Heimlich manoeuvre is a well-known intervention for the management of choking due to foreign body airway occlusion, but the evidence base for guidance on this topic is limited and guidelines differ. We measured pressures during abdominal thrusts in healthy volunteers. The angle at which thrusts were performed (upthrust vs circumferential) did not affect intrathoracic pressure. Self-administered abdominal thrusts produced similar pressures to those performed by another person. Chair thrusts, where the subject pushed their upper abdomen against a chair back, produced higher pressures than other manoeuvres. Both approaches should be included in basic life support teaching.

Does training respiratory physicians in clinical respiratory physiology and interpretation of pulmonary function tests improve core knowledge?

Lung function tests have a major role in respiratory medicine. Training in lung function tests is variable within the European Union. In this study, we have shown that an internship in a lung function tests laboratory significantly improved the technical and diagnostic skills of French respiratory trainees.

Validation of a health-related quality of life instrument for primary ciliary dyskinesia (QOL-PCD)

Background

Quality of life (QOL)-primary ciliary dyskinesia (PCD) is the first disease-specific, health-related QOL instrument for PCD. Psychometric validation of QOL-PCD assesses the performance of this measure in adults, including its reliability, validity and responsiveness to change.

Methods

Seventy-two adults (mean (range) age: 33 years (18–79 years); mean (range) FEV₁% predicted: 68 (26–115)) with PCD completed the 49-item QOL-PCD and generic QOL measures: Short-Form 36 Health Survey, Sino-Nasal Outcome Test 20 (SNOT-20) and St George Respiratory Questionnaire (SGRQ)-C. Thirty-five participants repeated QOL-PCD 10–14 days later to measure stability or reproducibility of the measure.

Results

Multitrait analysis was used to evaluate how the items loaded on 10 hypothesised scales: physical, emotional, role and social functioning, treatment burden, vitality, health perceptions, upper respiratory symptoms, lower respiratory symptoms and ears and hearing symptoms. This analysis of item-to-total correlations led to 9 items being dropped; the validated measure now comprises 40 items. Each scale had excellent internal consistency (Cronbach's α: 0.74 to 0.94). Two-week test–retest demonstrated stability for all scales (intraclass coefficients 0.73 to 0.96). Significant correlations were obtained between QOL-PCD scores and age and FEV₁. Strong relationships were also found between QOL-PCD scales and similar constructs on generic questionnaires, for example, lower respiratory symptoms and SGRQ-C (r=0.72, p<0.001), while weak correlations were found between measures of different constructs.

Conclusions

QOL-PCD has demonstrated good internal consistency, test–retest reliability, convergent and divergent validity. QOL-PCD offers a promising tool for evaluating new therapies and for measuring symptoms, functioning and QOL during routine care.

α-Tocopherol transfer protein mediates protective hypercapnia in murine ventilator-induced lung injury

RATIONALE

Hypercapnia is common in mechanically ventilated patients. Experimentally, 'therapeutic hypercapnia' can protect, but it can also cause harm, depending on the mechanism of injury. Hypercapnia suppresses multiple signalling pathways. Previous investigations have examined mechanisms that were known a priori, but only a limited number of pathways, each suppressed by CO₂, have been reported.

OBJECTIVE

Because of the complexity and interdependence of processes in acute lung injury, this study sought to fill in knowledge gaps using an unbiased screen, aiming to identify a specifically upregulated pathway.

METHODS AND RESULTS

Using genome-wide gene expression analysis in a mouse model of ventilator-induced lung injury, we discovered a previously unsuspected mechanism by which CO₂ can protect against injury: induction of the transporter protein for α-tocopherol, α-tocopherol transfer protein (αTTP). Pulmonary αTTP was induced by inspired CO₂ in two in vivo murine models of ventilator-induced lung injury; the level of αTTP expression correlated with degree of lung protection; and, absence of the αTTP gene significantly reduced the protective effects of CO₂. α-Tocopherol is a potent antioxidant and hypercapnia increased lung α-tocopherol in wild-type mice, but this did not alter superoxide generation or expression of NRF2-dependent antioxidant response genes in wild-type or in αTTP^-/- mice. In concordance with a regulatory role for α-tocopherol in lipid mediator synthesis, hypercapnia attenuated 5-lipoxygenase activity and this was dependent on the presence of αTTP.

CONCLUSIONS

Inspired CO₂ upregulates αTTP which increases lung α-tocopherol levels and inhibits synthesis of a pathogenic chemoattractant.

Altered lung structure and function in mid-childhood survivors of very preterm birth

RATIONALE

Survivors of preterm birth are at risk of chronic and lifelong pulmonary disease. Follow-up data describing lung structure and function are scarce in children born preterm during the surfactant era.

OBJECTIVES

To obtain comprehensive data on lung structure and function in mid-childhood from survivors of preterm birth. We aimed to explore relationships between lung structure, lung function and respiratory morbidity as well as early life contributors to poorer childhood respiratory outcomes.

METHODS

Lung function was tested at 9-11 years in children born at term (controls) and at ≤32 weeks gestation. Tests included spirometry, oscillatory mechanics, multiple breath nitrogen washout and diffusing capacity of the lung for carbon monoxide. Preterm children had CT of the chest and completed a respiratory symptoms questionnaire.

MAIN RESULTS

58 controls and 163 preterm children (99 with bronchopulmonary dysplasia) participated. Preterm children exhibited pulmonary obstruction and hyperinflation as well as abnormal peripheral lung mechanics compared with term controls. FEV₁ was improved by 0.10 z-scores for every additional week of gestation (95% CI 0.028 to 0.182; p=0.008) and by 0.34 z-scores per z-score increase in birth weight (0.124 to 0.548; p=0.002). Structural lung changes were present in 92% of preterm children, with total CT score decreased by 0.64 (-0.99 to -0.29; p<0.001) for each additional week of gestation. Obstruction was associated with increased subpleural opacities, bronchial wall thickening and hypoattenuated lung areas on inspiratory chest CT scans (p<0.05).

CONCLUSIONS

Abnormal lung structure in mid-childhood resulting from preterm birth in the contemporary era has important functional consequences.

Change in pulmonary mechanics and the effect on breathing pattern of high flow oxygen therapy in stable hypercapnic COPD

: We studied the effects of high flow oxygen therapy (HFOT) versus non-invasive ventilation (NIV) on inspiratory effort, as assessed by measuring transdiaphragmatic pressure, breathing pattern and gas exchange. Fourteen patients with hypercapnic COPD underwent five 30-min trials: HFOT at two flow rates, both with open and closed mouth, and NIV, applied in random order. After each trial standard oxygen therapy was reinstituted for 10 min. Compared with baseline, HFOT and NIV significantly improved breathing pattern, although to different extents, and reduced inspiratory effort; however, arterial carbon dioxide oxygen tension decreased but not significantly. These results indicate a possible role for HFOT in the long-term management of patients with stable hypercapnic COPD.

TRIAL REGISTRATION NUMBER

NCT02363920.

Timing of hypertonic saline and airway clearance techniques in adults with cystic fibrosis during pulmonary exacerbation: pilot data from a randomised crossover study

Background

Streamlining the timing of treatments in cystic fibrosis (CF) is important to optimise adherence while ensuring efficacy. The optimal timing of treatment with hypertonic saline (HTS) and airway clearance techniques (ACT) is unknown.

Objectives

This study hypothesised that HTS before ACT would be more effective than HTS during ACT as measured by Lung Clearance Index (LCI).

Methods

Adults with CF providing written informed consent were randomised to a crossover trial of HTS before ACT or HTS during ACT on consecutive days. ACT treatment consisted of Acapella Duet. Patients completed LCI and spirometry at baseline and 90 min post treatment. Mean difference (MD) and 95% CIs were reported.

Results

13 subjects completed the study (mean (SD) age 33 (12) years, forced expiratory volume in 1second % (FEV₁%) predicted 51% (22), LCI (no. turnovers) 14 (4)). Comparing the two treatments (HTS before ACT vs HTS during ACT), the change from baseline to 90 min post treatment in LCI (MD (95% CI) −0.02 (−0.63 to 0.59)) and FEV₁% predicted (MD (95% CI) −0.25 (−2.50 to 1.99)) was not significant. There was no difference in sputum weight (MD (95% CI) −3.0 (−14.9 to 8.9)), patient perceived ease of clearance (MD (95% CI) 0.4 (−0.6 to 1.3) or satisfaction (MD (95% CI) 0.4 (−0.6 to 1.5)). The time taken for HTS during ACT was significantly shorter (MD (95% CI) 14.7 (9.8 to 19.6)).

Conclusions

In this pilot study, HTS before ACT was no more effective than HTS during ACT as measured by LCI.

Trial registration number

NCT01753869; Pre-results.

Inhaled resveratrol treatments slow ageing-related degenerative changes in mouse lung

BACKGROUND

Lung ageing, a significant risk factor for chronic human lung diseases such as COPD and emphysema, is characterised by airspace enlargement and decreasing lung function. Likewise, in prematurely ageing telomerase null (terc-/-) mice, p53 stabilisation within diminishing numbers of alveolar epithelial type 2 cells (AEC2) accompanies reduced lung function. Resveratrol (RSL) is a plant phytoalexin that has previously showed efficacy in enhancing invertebrate longevity and supporting mammalian muscle metabolism when delivered orally. Here, we tested whether inhaled RSL could protect young, terc-/- mice from accelerated ageing of the lung.

METHODS

terc-/- mice aged 2 months inhaled 1 mg/kg RSL that was instilled intratracheally once per month for 3 months. One month after the last inhalation, whole lung function, structure and cellular DNA damage were evaluated and AEC2 survival was assessed by western blotting for survival pathway gene expression.

RESULTS

RSL treatments delayed the loss of lung compliance (p<0.05), maintained lung structure (p<0.001) and blocked parenchymal cell DNA damage as measured by TdT Nick-End Labeling (TUNEL). RSL, a known agonist of deacetylase SIRT1, supported AEC2 survival by stimulating SIRT1 expression, promoting p53 destabilisation and decreasing Bax expression and by maintaining expression levels of Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), activated p-Akt and p-Mdm2 and inactivated Phospho-Phosphatase and tensin homolog (p-PTEN).

CONCLUSIONS

RSL prophylaxis by inhalation is a potential approach for slowing ageing-related deterioration of lung function and structure by maintaining AEC2 integrity.

Occupational pesticide exposure and respiratory health: a large-scale cross-sectional study in three commercial farming systems in Ethiopia

RATIONALE

In the last decade, due to expansion of greenhouses and irrigated farms, the use of pesticides in Ethiopia has increased 6-13-fold leading to potential health risks.

OBJECTIVE

To investigate if occupational exposure to pesticides is associated with respiratory health effects in farmers and farm workers from commercial farming systems.

METHODS

We performed two cross-sectional surveys comprising different farming systems. In the first survey we studied respiratory symptoms among 1104 subjects of which 601 were occupationally exposed to pesticides (ie, 256 pesticide applicators, 345 re-entry workers) and 503 unexposed individuals. The second survey, carried out 2 years later in the same farming regions, additionally included lung function measurement and comprised a total of 387 study subjects of which 206 were occupationally exposed to pesticides (142 applicators and 64 re-entry workers) and 180 unexposed individuals.

RESULTS

We observed increased risks for chronic cough and shortness of breath (OR=3.15, 95% CI 1.56 to 6.36 and OR=6.67, 95% CI 2.60 to 17.58) among the exposed subjects as compared with unexposed individuals in the first survey. These results were corroborated in the second survey where we also observed reductions in FEV₁ (140 mL), forced expiratory flow 25%-75% (550 mL/s) and risk of FEV₁/FVC ratio <0.8 (OR=4.31, 95% CI 2.11 to 8.81) among pesticide exposed workers.

CONCLUSIONS

These findings indicate an increased risk of adverse respiratory health among workers exposed to pesticides. As those effects occurred in young workers (mean age 27 years) and within a relative short duration of exposure (4 years) implementation of stringent occupational health measures are warranted.

The effects of growing up on a farm on adult lung function and allergic phenotypes: an international population-based study

RATIONALE

Evidence has suggested that exposure to environmental or microbial biodiversity in early life may impact subsequent lung function and allergic disease risk.

OBJECTIVES

To investigate the influence of childhood living environment and biodiversity indicators on atopy, asthma and lung function in adulthood.

METHODS AND MEASUREMENTS

The European Community Respiratory Health Survey II investigated ∼10 201 participants aged 26-54 years from 14 countries, including participants' place of upbringing (farm, rural environment or inner city) before age 5 years. A 'biodiversity score' was created based on childhood exposure to cats, dogs, day care, bedroom sharing and older siblings. Associations with lung function, bronchial hyper-responsiveness (BHR), allergic sensitisation, asthma and rhinitis were analysed.

MAIN RESULTS

As compared with a city upbringing, those with early-life farm exposure had less atopic sensitisation (adjusted OR 0.46, 95% CI 0.37 to 0.58), atopic BHR (0.54 (0.35 to 0.83)), atopic asthma (0.47 (0.28 to 0.81)) and atopic rhinitis (0.43 (0.32 to 0.57)), but not non-atopic outcomes. Less pronounced protective effects were observed for rural environment exposures. Women with a farm upbringing had higher FEV₁ (adjusted difference 110 mL (64 to 157)), independent of sensitisation and asthma. In an inner city environment, a higher biodiversity score was related to less allergic sensitisation.

CONCLUSIONS

This is the first study to report beneficial effects of growing up on a farm on adult FEV₁. Our study confirmed the beneficial effects of early farm life on sensitisation, asthma and rhinitis, and found a similar association for BHR. In persons with an urban upbringing, a higher biodiversity score predicted less allergic sensitisation, but to a lesser magnitude than a childhood farm environment.

Effect of pulmonary exacerbations treated with oral antibiotics on clinical outcomes in cystic fibrosis

BACKGROUND

Despite extensive knowledge regarding the effect of pulmonary exacerbations treated with intravenous antibiotics on clinical outcomes in cystic fibrosis (CF), there is little known about the role of milder pulmonary exacerbations treated with oral antibiotics (oPEx).

METHODS

This was a retrospective cohort study of patients with CF followed at the Hospital for Sick Children and St. Michael's Hospital from 2009 to 2014. We evaluated the effect of oPEx on short-term clinical outcomes as the proportion of oPEx events in which 100% or 90% of baseline FEV₁% predicted was recovered at the end of treatment. We then examined the association of the number of oPEx events in the past 12 months on lung function (FEV₁% predicted) and nutritional status (body mass index (BMI) z-score) using a mixed-effects model.

RESULTS

There were a total of 2608 oPEx events in 570 subjects during the study period. In over half (53.4%) of oPEx events, lung function was already at 90% or higher of baseline FEV₁ at the initiation of oral antibiotic therapy and 82% were at 90% or higher of baseline FEV₁ at follow-up. In individuals with CF, one or more oPex events in the previous 12 months were associated with decreased FEV₁ compared with 12 months periods without oPex events. When the cumulative effect of oPExs on lung function was examined over the entire study period, patients with six or more oPEx events had the steepest rate of FEV₁ decline. oPEx events were not associated with changes in BMI.

CONCLUSIONS

oPEx events are associated with short-term loss of FEV₁ and have a negative effect on lung function over time.