Kathryn Angela Ramsey

Purpose Despite the volume of accumulating knowledge from prospective Aboriginal cohort studies, longitudinal data describing developmental trajectories in health and well-being is limited. The linkage of child and carer cohorts from a historical cross-sectional survey with longitudinal health-service and social-service administrative data has created a unique and powerful data resource that underpins the Western Australian Aboriginal Child Health Survey (WAACHS) linked data study. This study aims to provide evidence-based information to Aboriginal communities across Western Australia, governments and non-government agencies on the heterogeneous life trajectories of Aboriginal children and families. Participants This study comprises data from a historical cross-sectional household study of 5289 Aboriginal children from the WAACHS (2000–2002) alongside their primary (N=2113) and other (N=1040) carers, and other householders. WAACHS data were linked with Western Australia (WA) government administrative datasets up to 2020 including health, education, child protection, police and justice system contacts. The study also includes two non-Aboriginal cohorts from WA, linked with the same administrative data sources allowing comparisons of outcomes across cohorts in addition to between-group comparisons within the Aboriginal population. Findings to date Linked data coverage rates are presented for all WAACHS participants. Child health outcomes for the WAACHS children (Cohort 1) are described from birth into adulthood along with other outcomes including child protection and juvenile justice involvement. Future plans Analysis of data from both the child and carer cohorts will seek to understand the contribution of individual, family (intergenerational) and community-level influences on Aboriginal children’s developmental and health pathways, identify key developmental transitions or turning points where interventions may be most effective in improving outcomes, and compare service pathways for Aboriginal and non-Aboriginal children. All research is guided by Aboriginal governance processes and study outputs will be produced with Aboriginal leadership to guide culturally appropriate policy and practice for improving health, education and social outcomes.

Background: Multiple breath washout is a lung function test based on tidal breathing that assesses lung volume and ventilation distribution. The aim of this analysis was to use the Global Lung Function Initiative methodology to develop all-age reference equations for the multiple breath washout indices lung clearance index (LCI) and functional residual capacity (FRC). Methods: Multiple breath washout data from healthy individuals were collated from sites. Data were re-analysed using the latest software versions. Reference equations were derived using the lambda-mu-sigma method using the generalised additive models of location shape and scale programme in R. The impact of equipment type, inert tracer gas and equipment dead space volume on the derived reference ranges were investigated. Results: Data from 23 sites (n=3647 test occasions) were submitted. Reference equations were derived from 1579 unique observations from participants between the ages of 2 and 81 years. Equipment type, inert tracer gas and equipment dead space volume did not significantly affect the prediction equations for either LCI or FRC. Reference equations for LCI include age as the only predictor, whereas sex-specific reference equations for FRC included height and age. Conclusions: Global Lung Function Initiative reference equations for multiple breath washout variables provide a standard for reporting and interpretation of LCI and FRC.

Background: Multiple breath washout is a lung function test that assesses lung volume and ventilation distribution. The aim of this analysis was to use the Global Lung Function Initiative methodology to develop all-age reference equations for the multiple breath washout indices lung clearance index (LCI) and functional residual capacity (FRC). Methods: Multiple breath washout data from healthy individuals were collated. Data were re-analysed using the latest software versions. Reference equations were derived using the lambda-mu-sigma (LMS) method. The impact of equipment type, inert tracer gas, and equipment dead space volume on the derived reference ranges were investigated. Results: Data from 23 sites (n=3647 test occasions) were submitted. Reference equations were derived from 1581 unique observations from participants between the ages of 2 and 81 years. Equipment type, inert tracer gas, and equipment dead space volume did not significantly affect the prediction equations for either LCI or FRC. Reference equations for LCI include age as the only predictor, whereas sex-specific reference equations for FRC included height and age (Figure 1). Conclusions: Global Lung Function Initiative all-ages reference equations for LCI and FRC improve our understanding of how these outcomes evolve with age in healthy subjects and provide a new standard for reporting and interpretation. Funding: ERS TF-2020-01

We investigated the accuracy of the molar mass (MM) and CO₂ sensors of a commercial multiple-breath washout device (ndd Medizintechnik AG, Switzerland). We identified humidity and respiratory exchange ratio-dependent errors that in most measurements resulted in an overestimation of expired nitrogen concentrations, and consequently, MBW results. Functional residual capacity and lung clearance index decreased by 6.6% and 9.9%, respectively. Despite improved signal accuracy, the difference in FRC between the EOPL and body plethysmography increased.

This document updates the 2005 European Respiratory Society (ERS) and American Thoracic Society (ATS) technical standard for the measurement of lung volumes. The 2005 document integrated the recommendations of an ATS/ERS task force with those from an earlier National Heart, Lung, and Blood Institute workshop that led to the publication of background papers between 1995 and 1999 and a consensus workshop report with more in-depth descriptions and discussion. Advancements in hardware and software, new research and emerging approaches have necessitated an update to the 2005 technical standard to guide laboratory directors, physiologists, operators, pulmonologists and manufacturers. Key updates include standardisation of linked spirometry, new equipment quality control and validation recommendations, generalisation of the multiple breath washout concept beyond nitrogen, a new acceptability and grading system with addition of example tracings, and a brief review of imaging and other new techniques to measure lung volumes. Future directions and key research questions are also noted.

Background: Accurate breath detection is essential for the computation of outcomes in the multiple-breath washout (MBW) technique. This is particularly important in young children, where irregular breathing is common, and the designation of inspirations and expirations can be challenging. Aim: To investigate differences between a commercial and a novel breath-detection algorithm and to characterize effects on MBW outcomes in children. Methods: We replicated the signal processing and algorithms used in Spiroware software (v3.3.1, Eco Medics AG). We developed a novel breath detection algorithm (custom) and compared it to Spiroware using 2,455 nitrogen (N₂) and 325 sulfur hexafluoride (SF₆) trials collected in infants, children, and adolescents. Results: In 83% of N₂ and 32% of SF₆ trials, the Spiroware breath detection algorithm rejected breaths and did not use them for the calculation of MBW outcomes. Our custom breath detection algorithm determines inspirations and expirations based on flow reversal and corresponding CO₂ elevations, and uses all breaths for data analysis. In trials with regular tidal breathing, there were no differences in outcomes between algorithms. However, in 10% of pre-school children tests the number of breaths detected differed by more than 10% and the commercial algorithm underestimated the lung clearance index by up to 21%. Conclusion: Accurate breath detection is challenging in young children. As the MBW technique relies on the cumulative analysis of all washout breaths, the rejection of breaths should be limited. We provide an improved algorithm that accurately detects breaths based on both flow reversal and CO₂ concentration.