Background: Airway bacterial infection and inflammation are often present in children with bronchiectasis. Systemic inflammation has also been reported. Currently, there are no data on the association between systemic inflammatory markers with airway pathogens or neutrophilia in children with bronchiectasis. We aimed to define the bronchoalveolar lavage (BAL) pathogens (bacteria and viruses), and cytology in children with bronchiectasis and to explore any association between peripheral inflammatory markers and airway neutrophilia. Methods: Participants numbering 402, aged <18 years, with peripheral blood and BAL results within 3 months of diagnosis of bronchiectasis were included. Blood and BAL results were reviewed and analysed for possible associations. Results: Of 355 children (88.31%), cultured bacteria from BAL and Haemophilus influenzae (n = 185) were the most frequent. A virus was identified in 131 (32.59%). Adenovirus (n = 69) was most common. Children numbering 279 (69.40%) had airway neutrophilia (neutrophils > 15%) which was associated with the presence of H. influenzae (OR 2.03 95% CI 1.31-3.15, p = 0.002), S. pneumonia 2.41 (95% CI 1.36-4.29, p = 0.003), and Adenovirus (OR 2.06 95% CI 1.06-4.04, p = 0.033). Airway neutrophilia was associated with raised CRP (OR 2.26 95% CI 1.14-4.49, p = 0.019), but there were no other systemic inflammatory markers including monocyte/lymphocyte ratio, neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, and platelet/mean platelet volume ratio. Conclusions: In children, there is an association between airway neutrophilia and raised CRP in bronchiectasis, but not with other peripheral inflammatory markers. There is a need to identify non-invasive inflammatory markers in children with bronchiectasis.

Background:Achieving good asthma control is a goal of asthma management. In children, asthma control and quality-of-life assessments include determining the presence of wheeze. However, wheeze is unreliably reported with high disagreement (>50%) between parental and physician detection of wheeze. Objectively defining wheeze using WheezeScan™ (a user-friendly, artificial intelligence-based device) could improve assessment of asthma control and hence management. Objective:Our primary aim is to determine whether adding WheezeScan™ to routine clinical care improves parental asthma control assessment (ACA) in children (aged 4-11 years). Our secondary aims are to examine the impact of WheezeScan™ upon patient-reported outcomes (PROs), the parent asthma management self-efficacy scale (PAMS), healthcare costs and ease of WheezeScan™ use. The primary hypothesis is that using WheezeScan™ alters the ACA group. Methods:Our multicentre prospective cohort study involves 125 children with specialist-confirmed asthma. Over 5 weeks, parents/caregivers use the WheezeScan™ twice-daily at home and whenever wheezing is suspected. After the first week of using the WheezeScan™, asthma medications may be adjusted based upon the child's asthma control score and WheezeScan™ data. Study outcomes are collected at baseline, week 1 and week 5. Our primary end-point is the proportion of children whose assessment of asthma control changed between week 1 and baseline, based upon parental assessments using WheezeScan™ data. Secondary outcomes are PROs (asthma-related quality of life), PAMS, healthcare costs and WheezeScan™ ease of use. Conclusions:This protocol describes our study to determine whether using digital technology to accurately identify wheeze in children with asthma improves their asthma assessment and asthma-related PROs, including PAMS and healthcare costs.

INTRODUCTION:Preschool wheeze and asthma are associated with substantial morbidity and impaired future lung function. Yet, wheeze is unreliably reported with high disagreement (>50%) between parental and physician observations. Objectively defining wheeze and its reversibility could enable an earlier asthma diagnosis and improve preschool wheeze management.Our primary aim is to determine in preschool children (aged 0.5-6 years) suspected of asthma whether adding WheezeScan to routine clinical assessment (vs assessment without WheezeScan) improves the diagnosis of asthma. Our primary hypothesis is that using WheezeScan in preschool children suspected of asthma is associated with increased definitive asthma diagnoses in this age group. Our secondary aims are to (a) examine the effect of using WheezeScan on patient-reported outcomes (PROs) and (b) healthcare costs. Our secondary hypothesis is that using WheezeScan in preschool children suspected of asthma is associated with improved quality of life without incurring additional healthcare costs. METHODS AND ANALYSIS:Our multicentre prospective cohort study involves recruiting 102 preschool children suspected of asthma. WheezeScan, a user-friendly digital device, incorporates artificial intelligence to objectively define wheeze and its response to bronchodilators. Over 6 weeks, parents/caregivers use the WheezeScan two times per day and whenever wheezing is suspected. If wheeze is detected, an inhaled short-acting β2-agonist is administered and WheezeScan determines if wheeze resolves thereafter.Our primary endpoint is the proportion of children with a definitive asthma diagnosis, compared with baseline, based on the treating clinician's assessment using WheezeScan data. Our secondary outcomes are PROs, reflecting generic health-related quality-of-life and cough-specific (if chronic cough present) outcomes and health costs. ETHICS AND DISSEMINATION:The Children's Health Queensland Human Research Ethics Committee (HREC/23/QCHQ/100691) and the Queensland University of Technology Office of Research Ethics and Integrity approved the study. We will publish and share results with the academic and healthcare communities and relevant patient organisations. TRIAL REGISTRATION NUMBER:Australian New Zealand Clinical Trials Registry ACTRN12623000904673.

Acute respiratory exacerbations in bronchiectasis are important as they impair quality of life and are associated with accelerated lung function decline. Yet, no validated methods exist to identify children at increased risk of exacerbations. We therefore determined if peripheral blood gene expression (GE) signatures can identify those at risk of an impending exacerbation. Thirty-one children with bronchiectasis had RNA extracted from peripheral blood collected whilst they were clinically stable, with 22 having an exacerbation during the next 3 months. Microarray assays using the HumanHT-12 v4.0 Expression BeadChip identified differentially expressed genes (p value ≤ 0.05, fold change > 1.5). The top targets were verified using real-time quantitative polymerase chain reaction (rt-qPCR) assays, and receiver operating characteristics and area under the curve (AUC) were assessed. Functional analysis of these genes was performed using Ingenuity Pathway Analysis. Overall, 647 entities were significantly dysregulated (p < 0.05) in the exacerbation group (n = 22), and pathway analysis identified neutrophil degranulation as the dominant affected pathway, which was also significantly inhibited (p < 0.001). Forty entities (32 genes) were associated with a future exacerbation (p ≤ 0.05, fold change ≥ 1.5) and six genes (ANXA3, ALAS2, DEFA1, ALPL, SNCA, PROK2) were verified using RT-qPCR (all p < 0.04) as the most discriminatory. DEFA1 and ANXA3 had the highest AUC (0.92, 95

OBJECTIVES:To determine whether an 8-week, play-based therapeutic exercise program increases the proportion of children with bronchiectasis who remain exacerbation-free over 12-months. Secondary objectives were to assess effects on time of exacerbations, fundamental movement skill (FMS) proficiency, moderate-to-vigorous physical activity (MVPA), aerobic fitness, perceived movement competence, and health-related quality of life (HRQoL). DESIGN:Multi-site, observer-blinded, parallel-group randomised controlled trial. METHODS:Children aged 4 to 13-years with bronchiectasis, were randomised 1:1 to intervention or waitlist control. The 8-week intervention comprised weekly 60-minute group sessions in community venues, incorporating play-based activities targeting FMS and aerobic fitness, alongside a twice-weekly home program. Primary and secondary outcomes were assessed at baseline, immediately post-intervention, and at 6- and 12-months. Analyses used intention-to-treat with multiple imputation for missing data. RESULTS:Forty-seven children (mean age = 7.3 years ± SD 2.4) were randomised. At 12-months, the estimated odds of remaining exacerbation-free over 12 months were higher in the intervention group than in the control group (OR 1.51, 95% CI 0.32-7.5), although the association was not statistically significant. Median time to first exacerbation was longer in the intervention participants than controls (175 vs 82 days, p = 0.38). Daily MVPA increased significantly post-intervention (+16.8 min/day; p = 0.011) but was unsustained at 6- and 12-month follow-up. No significant group differences were observed for FMS, aerobic fitness, perceived competence, or HRQoL. CONCLUSIONS:A developmentally appropriate, play-based therapeutic exercise program was associated with short-term increases in daily physical activity and clinically relevant reductions in exacerbation frequency were suggested, although estimates were imprecise and not statistically significant. Therapeutic exercise as a potential adjunct to routine care warrants further investigation in adequately powered trials.

Background In most chronic airway diseases, identifying phenotypes has advanced clinical practice and research. However, no such phenotypes exist for paediatric bronchiectasis. We therefore sought to develop robust paediatric bronchiectasis phenotypes and to investigate whether they were associated with relevant clinical outcomes. Methods Latent class analysis was independently applied to two study cohorts of children with bronchiectasis. Data from 158 children from one study (BEST, development cohort) were used to identify phenotypes and their associations with relevant clinical outcomes. A cohort of 198 children from a second study (BAMP) was used to validate these phenotypes and compare findings for consistency. Results A three-class model was the best fit in the BEST cohort. Based on clinical characteristics, we labelled the phenotypes as ‘Baseline-Well’, ‘Wheeze-Dyspnoea Predominant’ and ‘Daily Wet-Cough Predominant’. These phenotypes were validated in the BAMP cohort. In both development and validation cohorts, the ‘Daily Wet-Cough Predominant’ phenotype was associated with higher numbers of bronchiectatic lobes (OR 1.61, 95% CI 0.61 to 4.27; and 3.06, 95% CI 1.30 to 7.21 for BEST and BAMP cohorts, respectively) and more bronchiectasis-related hospitalisations ever at enrolment (incidence rate ratio (IRR) 4.33, 95% CI 1.94 to 9.66; and 2.96, 95% CI 1.07 to 8.20, respectively) and also within 2 years of enrolment (IRR 2.68, 95% CI 1.24 to 5.8; and 1.54, 95% CI 0.72 to 3.28, respectively) than the reference phenotype, although the strengths of evidential support differed. Conclusions We identified and validated three novel paediatric bronchiectasis phenotypes, and linked them to distinct clinical outcomes. These phenotypes might enable targeted interventions and improve participant selection for clinical trials.

BACKGROUND:Hypoxaemia occurs in approximately 30% of children undergoing anaesthesia for flexible bronchoscopy. Nasal high-flow oxygen (NHF) can prolong safe apnoea time and be used in children with abnormal airways. During flexible bronchoscopy, there is limited evidence that NHF may confer advantages over the current standard practice in avoiding hypoxaemia. This study aimed to evaluate the feasibility of recruitment to a protocol investigating NHF during anaesthesia for flexible bronchoscopy, with the objective of reducing rescue oxygenation and hypoxaemia. METHODS:The BUFFALO study was a bi-centre, unmasked, randomised, controlled, parallel-group pilot trial comparing NHF techniques with standard practice during anaesthesia. Children aged >37 weeks gestational age to 16 years presenting for elective bronchoscopy were randomised to NHF or standard-care oxygen post-induction of anaesthesia. Outcomes included the feasibility of recruitment, hypoxaemic events, rescue oxygenations, adherence to trial procedures, acceptability of the intervention, and completion rates of data collection methods. RESULTS:Of the 707 children screened, 89 children were eligible, 81 children were recruited, 43 to the NHF, and 38 to the standard care group. The feasibility outcomes were: proportion of eligible children recruited 91% (95%CI [85,97]), protocol adherence 93% (95%CI [87,98]), and completion rate 100%. CONCLUSION:The technique of using NHF during flexible bronchoscopies in children and the protocol for this trial were feasible in the two participating centres. However, respiratory physicians' hesitancy to use this technique in high-risk children and concerns about the potential for translocation of upper airway infectious material into the lower airways reduced the number of eligible patients.

Background:Quality of life (QoL), the highest prioritised outcome by children with bronchiectasis and their parents, is a patient-reported outcome measure increasingly considered essential when evaluating health and interventions. Despite this, there are no validated instruments that specifically measure QoL related to bronchiectasis in children. We aimed to develop and validate a new bronchiectasis child-specific parent-proxy QoL instrument (BC-QoL). Methods:We developed a draft 44-item BC-QoL and subsequently conducted a prospective cohort study in which 142 parents completed the draft BC-QoL and six other measures (two validated cough scores; the Parent-proxy Children's Acute Cough-specific QoL questionnaire; the Depression, Anxiety and Stress Scale - 21-items; the RAND-36; and the Pediatric Quality of Life Inventory (PedsQL™ 4.0)) to assess the convergent and discriminant validity of the BC-QoL. The questionnaires were completed over 3 weeks at different phases of a child's illness (stable state, exacerbation and/or recovery). Responses were analysed using psychometric and clinical impact techniques to reduce the number of items and determine the instrument's reliability and validity. The minimal important difference (MID) was also calculated. Results:The final 23-item BC-QoL instrument with its three domains (emotional, physical and social well-being) demonstrated high split-half reliability (0.95), Cronbach's alpha (0.97), repeatability (intraclass coefficient 0.74, 95% CI 0.62-0.82), validity and responsiveness. BC-QoL's domains significantly correlated with those of the PedsQL™ 4.0 (Spearman correlations: emotional=0.43, social=0.41, physical=0.47). BC-QoL's MID ranged from 0.74 to 1.32. Conclusion:This study provides evidence supporting the validity and reliability of BC-QoL. The BC-QoL can be used to evaluate the impact and effectiveness of interventions and better understand the disease burden among children with bronchiectasis.

ABSTRACT Achieving good asthma control is a goal of asthma management. In children, asthma control and quality-of-life assessments include determining the presence of wheeze. However, wheeze is unreliably reported with high disagreement (>50%) between parental and physician detection of wheeze. Objectively defining wheeze using WheezeScan™ (a user-friendly, artificial intelligence-based device) could improve assessment of asthma control and hence management. Our primary aim is to determine whether adding WheezeScan™ to routine clinical care improves parental asthma control assessment (ACA) in children (aged 4–11 years). Our secondary aims are to examine the impact of WheezeScan™ upon patient-reported outcomes (PROs), the parent asthma management self-efficacy scale (PAMS), healthcare costs and ease of WheezeScan™ use. The primary hypothesis is that using WheezeScan™ alters ACA group. Our multicentre prospective cohort study involves 125 children with specialist-confirmed asthma. Over 5-weeks, parents/caregivers use the WheezeScan™ twice-daily at home and whenever wheezing is suspected. After the first week of using the WheezeScan™, asthma medications may be adjusted based upon the child's asthma control score and WheezeScan™ data. Study outcomes are collected at baseline, week-1 and week-5. Our primary endpoint is the proportion of children whose assessment of asthma control changed between week-1 and baseline, based upon parental assessments using WheezeScan™ data. Secondary outcomes are PROs (asthma-related quality-of-life), PAMS, healthcare costs and WheezeScan™ ease of use. This protocol describes our study to determine if using digital technology to accurately identify wheeze in children with asthma improves their asthma assessment, asthma-related PROs, including PAMS, and healthcare costs.

OBJECTIVES:Cough in children is the most common reason for seeking healthcare in Australia. When chronic, it is associated with decreased quality-of-life in parents/carers and significant societal costs. Despite this, the spillover effect of chronic cough on parents/carers is seldom accounted for in economic evaluations of interventions. We aimed to develop a new method of estimating spillover health utility in this population in Australia. METHODS:We conducted a discrete choice experiment on hypothetical health states based on the Parent-Proxy Child Cough Quality of Life questionnaire. These were analyzed using a garbage-class multinomial logit model (GCL). We also obtained visual analog scale scores for 6 health states and mapped them to the latent discrete choice experiment utilities, rescaling them to the 0 to 1 health utility scale required to estimate quality-adjusted life-years. RESULTS:A total of 550 participants broadly representative of Australian parents completed our survey. Parental concerns about their child being able to lead a normal life had the largest coefficients in the GCL. The resulting scoring algorithm had a minimum score of.21, and a maximum of 1 (full health). CONCLUSIONS:We have developed a new method of estimating spillover health utility values in parents of children with chronic cough in Australia. This study is also a use case for the application of GCL in extracting respondent nontrading behavior, which may cause inaccurate preference estimates, and a visual analog scale based anchoring methodological approach that could be iterated in further research. We have developed an R package and shiny app to allow the easy estimation of spillover utility scores from Parent-Proxy Child Cough Quality of Life questionnaire responses.

Introduction Bronchiectasis is a worldwide chronic lung disorder where exacerbations are common. It affects people of all ages, but especially Indigenous populations in high-income nations. Despite being a major contributor to chronic lung disease, there are no licensed therapies for bronchiectasis and there remain relatively few randomised controlled trials (RCTs) conducted in children and adults. Our RCT will address some of these unmet needs by evaluating whether the novel mucoactive agent, erdosteine, has a therapeutic role in children and adults with bronchiectasis.Our primary aim is to determine in children and adults aged 2–49 years with bronchiectasis whether regular erdosteine over a 12-month period reduces acute respiratory exacerbations compared with placebo. Our primary hypothesis is that people with bronchiectasis who regularly use erdosteine will have fewer exacerbations than those receiving placebo.Our secondary aims are to determine the effect of the trial medications on quality of life (QoL) and other clinical outcomes (exacerbation duration, time-to-next exacerbation, hospitalisations, lung function, adverse events). We will also assess the cost-effectiveness of the intervention.Methods and analysis We are undertaking an international multicentre, double-blind, placebo-RCT to evaluate whether 12 months of erdosteine is beneficial for children and adults with bronchiectasis. We will recruit 194 children and adults with bronchiectasis to a parallel, superiority RCT at eight sites across Australia, Malaysia and Philippines. Our primary endpoint is the rate of exacerbations over 12 months. Our main secondary outcomes are QoL, exacerbation duration, time-to-next exacerbation, hospitalisations and lung function.Ethics and dissemination The Human Research Ethics Committees (HREC) of Children’s Health Queensland (for all Australian sites), University of Malaya Medical Centre (Malaysia) and St. Luke’s Medical Centre (Philippines) approved the study. We will publish the results and share the outcomes with the academic and medical community, funding and relevant patient organisations.Trial registration number ACTRN12621000315819.

Chronic cough in children is a common condition for which patients seek medical attention, and there are many etiologies. Of the various causes of chronic cough in children, protracted bacterial bronchitis (PBB) is one of the commonest causes, and bronchiectasis is one of the most serious. Together, they lie on different ends of the spectrum of chronic wet cough in children. Cough is often the only symptom present in children with PBB and bronchiectasis. This review highlights the role of cough as a marker for the presence of these conditions, as well as an outcome endpoint for treatment and research.

Objectives To explore the experiences and perceptions of children with bronchiectasis and their parents regarding an 8-week play-based therapeutic exercise programme.Design Qualitative study with inductive content analysis.Setting Individual semistructured interviews were conducted. Interview recordings were transcribed verbatim, and coding was guided by the content. Content categories were established via consensus moderation.Participants 10 parents and 10 children with bronchiectasis aged 5–12 years.Results From the perspective of children, the most important components of the programme were fun with friends and being active at home as a family. Parents valued the community-based sessions, perceived the programme to be engaging and motivating. Parents perceived improvements in their child’s endurance, coordination and physical activity level. They described the home programme as fun but noted that finding time was difficult. Both parents and children thought that in-person exercise sessions would be better than exercise sessions delivered online.Conclusions Children who participated in the play-based exercise programme, found it fun, motivating and accessible. Parents perceived positive impacts on fitness, coordination and physical activity.Trial registration number The trial was registered with, Australian and New Zealand Clinical Trials Register (ACTRN12619001008112).

BACKGROUND:The parent-proxy paediatric chronic cough quality of life questionnaire (PC-QoL) is a commonly used measure of spillover quality of life in parents of children with chronic cough. To date, spillover health utility in these parents is not routinely estimated largely due to the lack of a suitable instrument. Their perspective is not included in economic evaluations of interventions for their children. We explored developing a health state classification system based on the PC-QoL for measuring health utility spill over in this population. METHODS:This study included PC-QoL 8-item responses of 653 parents participating in a prospective cohort study about paediatric chronic cough. Exploratory factor analysis (EFA) and Rasch analysis were used to examine dimensionality and select potential items and level structure. RESULTS:EFA indicated that the PC-QoL had one underlying domain. Rasch analysis indicated threshold disordering in all items which improved when items were collapsed from seven to four levels. Two demonstrated differential item functioning (DIF) by diagnosis or ethnicity and were excluded from the final scale. This scale satisfied Rasch assumptions of local independence and unidimensionality and demonstrated acceptable fit to the Rasch model. It was presented to and modified by an expert panel and a consumer panel. The resulting classification system had six items, each with four levels. DISCUSSION:The PC-QoL can conform to a Rasch model with minor modifications. It may be a good basis for the classification system of a child cough-specific PBM. A valuation study is required to estimate preference weights for each item and to estimate health utility in parents of children with chronic cough.

Abstract Background: Neuroendocrine hyperplasia of infancy (NEHI) is a rare childhood disease of the airways. Existing literature regarding the aetiology of NEHI is limited and predominately centred on genetic mutations. However, there does not appear to be a common genetic mutation among all children with NEHI, suggesting that other causative factors likely contribute to disease pathogenesis. While no infectious disease has been attributed to the aetiology of NEHI, infectious agents are certainly known to precipitate or exacerbate other Childhood Interstitial Lung Diseases (ChILDs). Case presentation: We report the presence of Pneumocystis jirovecii in the lungs of five infants with NEHI. Conclusions: The significance of this association is unclear but is suspicious for an immunological or other pulmonary aberrancy among children with NEHI that predisposes to P. jirovecii infection. Alternatively, P jirovecii may be an important co-factor in the pathogenesis of NEHI, or simply be an innocent bystander within the lung. This finding may help to explain the pathogenesis of this poorly understood disease. Future studies comparing the clinical course of children with NEHI infected with P. jirovecii against those without infection may further clarify the pathogenesis of this condition.

Rationale: Conventionally considered irreversible, bronchiectasis has been demonstrated to be reversible in children in small studies. However, the factors associated with radiographic reversibility of bronchiectasis have yet to be defined. Objectives: In a large cohort of children with bronchiectasis, we aimed to determine: 1) if and to what extent bronchiectasis is reversible and 2) factors associated with radiographic chest high-resolution computed tomography (cHRCT) resolution. Methods: We identified children with bronchiectasis who had a repeat multidetector cHRCT scan between 2010 and 2021. We excluded those with cystic fibrosis, surgical pulmonary resection, traction bronchiectasis only, or lobar opacification. Measurements and Main Results: cHRCT scans were scored using the modified Reiff score (MRS) with a pediatric correction. Resolution was defined as an absence of abnormal bronchoarterial ratio (>0.8) on the second cHRCT scan. We included 142 children (median age, 5 years; IQR, 2.6-7.4). Inter- and intrarater agreement in MRSs was excellent (weighted kappa = 0.83-0.86 and 0.95, respectively). There was radiographic resolution in 57 of 142 patients (40.1%), improvement in 56 of 142 (39.4%), and no change or worsening in 29 of 142 (20.4%). Pseudomonas aeruginosa (PsA) was absolutely associated with a lack of resolution. On multivariable regression, in those without PsA cultured, younger age at the time of diagnosis (risk ratio [RR], 0.94; 95% confidence interval [CI], 0.88-0.99), lower MRS (RR, 0.89; 95% CI, 0.82-0.97), and lower annual rate of exacerbations requiring intravenous antibiotic therapy (RR, 0.60; 95% CI, 0.37-0.98) increased the likelihood of radiographic resolution. Conclusions: This first large cohort confirms that bronchiectasis in children is often reversible with appropriate management. Younger children and those with lesser radiographic severity at diagnosis were most likely to exhibit radiographic reversibility, whereas those with PsA infection were least likely.

Introduction Elective flexible bronchoscopy (FB) is now widely available and standard practice for a variety of indications in children with respiratory conditions. However, there are no randomised controlled trials (RCTs) that have examined its benefits (or otherwise).Our primary aim is to determine the impact of FB on the parent-proxy quality-of-life (QoL) scores. Our secondary aims are to determine if undertaking FB leads to (a) change in management and (b) improvement of other relevant patient-reported outcome measures (PROMs). We also quantified the benefits of elective FB (using 10-point Likert scale). We hypothesised that undertaking elective FB will contribute to accurate diagnosis and therefore appropriate treatment, which will in turn improve QoL and will be deemed to be beneficial from patient and doctor perspectives.Methods and analysis Our parallel single-centre, single-blind RCT (commenced in May 2020) has a planned sample size of 114 children (aged <18 years) recruited from respiratory clinics at Queensland Children’s Hospital, Brisbane, Australia. Children are randomised (1:1 concealed allocation) within two strata: age (≤2 vs >2 years) and indication for FB (chronic cough vs other indications) to either (a) early arm (intervention where FB undertaken within 2 weeks) or (b) delayed (control, FB undertaken at usual wait time). Our primary outcome is the difference between groups in their change in QoL at the T2 timepoint when the intervention group has had the FB and the control group has not. Our secondary outcomes are change in management, change in PROMs, adverse events and the Likert scales.Ethics and dissemination The human research ethics committee of the Queensland Children’s Hospital granted ethical clearance (HREC/20/QCHQ/62394). Our RCT is conducted in accordance with Good Clinical Practice and the Australian legislation. Results will be disseminated through conference presentations, teaching avenues, workshops, websites and publications.Registration Australia New Zealand Clinical Trial Registry ACTRN12620000610932.

Background Hypoxaemia occurs in approximately 30% of children during anaesthesia for flexible bronchoscopy. High-flow nasal oxygen (HFNO) can prolong safe apnoea time and be used in children with abnormal airways. During flexible bronchoscopy, there is limited evidence if HFNO confers advantages over current standard practice in avoiding hypoxaemia. The aim is to investigate feasibility of HFNO use during anaesthesia for flexible bronchoscopy to reduce frequency of rescue oxygenation and hypoxaemia. Methods BUFFALO is a bi-centre, unmasked, randomised controlled, parallel group, protocol for a pilot trial comparing HFNO techniques to standard practice during anaesthesia. Children ( n = 81) aged > 37 weeks to 16 years presenting for elective bronchoscopy who fulfil inclusion but not exclusion criteria will be randomised prior to the procedure to HFNO or standard care oxygenation post induction of anaesthesia. Maintenance of anaesthesia with HFNO requires total venous anaesthesia (TIVA) and with standard, either inhalational or TIVA at discretion of anaesthetist in charge of the patient. Outcomes will include the feasibility of recruitment and adherence to trial procedures, acceptability of the intervention of the protocol and completion rates of data collection methods. Discussion Findings of this trial will determine feasibility to plan for a larger multicentre randomised clinical trial and support the feasibility of the proposed study procedures. Trial registration BUFFALO trial was registered with Australia and New Zealand Clinical Trials Registry (TRN12621001635853) on 29 November 2021 and commenced recruitment in May 2022. https://www.anzctr.org.au/ . The primary manuscript will be submitted for publication in a peer-reviewed journal.