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Sandhu D, Redmond JL, Smith NMJ, Short C, Saunders CJ, Couper JH, Fullerton CJ, Richmond G, Talbot NP, Davies JC, Ritchie GAD, Robbins PA. Computed cardiopulmonography and the idealized lung clearance index, iLCI 2.5, in early-stage cystic fibrosis. J Appl Physiol (1985) 2023; 135:205-216. [PMID: 37262105 PMCID: PMC10393329 DOI: 10.1152/japplphysiol.00744.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 05/02/2023] [Accepted: 05/27/2023] [Indexed: 06/03/2023] Open
Abstract
This study explored the use of computed cardiopulmonography (CCP) to assess lung function in early-stage cystic fibrosis (CF). CCP has two components. The first is a particularly accurate technique for measuring gas exchange. The second is a computational cardiopulmonary model where patient-specific parameters can be estimated from the measurements of gas exchange. Twenty-five participants (14 healthy controls, 11 early-stage CF) were studied with CCP. They were also studied with a standard clinical protocol to measure the lung clearance index (LCI2.5). Ventilation inhomogeneity, as quantified through CCP parameter σlnCl, was significantly greater (P < 0.005) in CF than in controls, and anatomical deadspace relative to predicted functional residual capacity (DS/FRCpred) was significantly more variable (P < 0.002). Participant-specific parameters were used with the CCP model to calculate idealized values for LCI2.5 (iLCI2.5) where extrapulmonary influences on the LCI2.5, such as breathing pattern, had all been standardized. Both LCI2.5 and iLCI2.5 distinguished clearly between CF and control participants. LCI2.5 values were mostly higher than iLCI2.5 values in a manner dependent on the participant's respiratory rate (r = 0.46, P < 0.05). The within-participant reproducibility for iLCI2.5 appeared better than for LCI2.5, but this did not reach statistical significance (F ratio = 2.2, P = 0.056). Both a sensitivity analysis on iLCI2.5 and a regression analysis on LCI2.5 revealed that these depended primarily on an interactive term between CCP parameters of the form σlnCL*(DS/FRC). In conclusion, the LCI2.5 (or iLCI2.5) probably reflects an amalgam of different underlying lung changes in early-stage CF that would require a multiparameter approach, such as potentially CCP, to resolve.NEW & NOTEWORTHY Computed cardiopulmonography is a new technique comprising a highly accurate sensor for measuring respiratory gas exchange coupled with a cardiopulmonary model that is used to identify a set of patient-specific characteristics of the lung. Here, we show that this technique can improve on a standard clinical approach for lung function testing in cystic fibrosis. Most particularly, an approach incorporating multiple model parameters can potentially separate different aspects of pathological change in this disease.
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Affiliation(s)
- Dominic Sandhu
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | | | | | - Christopher Short
- Royal Brompton and Harefield Hospitals, Guys and St Thomas' Trust, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
- European Cystic Fibrosis Society, Lung Clearance Index Core Facility, London, United Kingdom
| | - Clare J Saunders
- Royal Brompton and Harefield Hospitals, Guys and St Thomas' Trust, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
- European Cystic Fibrosis Society, Lung Clearance Index Core Facility, London, United Kingdom
| | - John H Couper
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Christopher J Fullerton
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Graham Richmond
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Nick P Talbot
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Jane C Davies
- Royal Brompton and Harefield Hospitals, Guys and St Thomas' Trust, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
- European Cystic Fibrosis Society, Lung Clearance Index Core Facility, London, United Kingdom
| | - Grant A D Ritchie
- Department of Chemistry, University of Oxford, Oxford, United Kingdom
| | - Peter A Robbins
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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2
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Stanojevic S, Bowerman C, Robinson P. Multiple breath washout: measuring early manifestations of lung pathology. Breathe (Sheff) 2022; 17:210016. [PMID: 35035543 PMCID: PMC8753656 DOI: 10.1183/20734735.0016-2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 07/13/2021] [Indexed: 11/05/2022] Open
Abstract
The multiple breath washout (MBW) test measures the efficiency of gas mixing in the lungs and has gained significant interest over the past 20 years. MBW outcomes detect early lung function impairment and peripheral airway pathology, through its main outcome measure lung clearance index (LCI). LCI measures the number of lung turnovers required to washout an inert tracer gas. MBW is performed during normal (tidal) breathing, making it particularly suitable for young children or those who have trouble performing forced manoeuvres. Additionally, research in chronic respiratory disease populations has shown that MBW can detect acute clinically relevant changes before conventional lung function tests, such as spirometry, thus enabling early intervention. The development of technical standards for MBW and commercial devices have allowed MBW to be implemented in clinical research and potentially routine clinical practice. Although studies have summarised clinimetric properties of MBW indices, additional research is required to establish the clinical utility of MBW and, if possible, shorten testing time. Sensitive, feasible measures of early lung function decline will play an important role in early intervention for people living with respiratory diseases. Educational aim To describe the multiple breath washout test, its applications to lung pathology and respiratory disease, as well as directions for future research.
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Affiliation(s)
- Sanja Stanojevic
- Dept of Community Health and Epidemiology, Dalhousie University, Halifax, NS, Canada
| | - Cole Bowerman
- Dept of Community Health and Epidemiology, Dalhousie University, Halifax, NS, Canada
| | - Paul Robinson
- Dept of Respiratory Medicine, Children's Hospital at Westmead, Sydney, Australia.,The Children's Hospital at Westmead Clinical School, The University of Sydney, Sydney, Australia
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Handley BM, Bozier J, Jeagal E, Rutting S, Schoeffel RE, Robinson PD, King GG, Milne S, Thamrin C. Controlled versus free breathing for multiple-breath nitrogen washout in asthma. ERJ Open Res 2021; 7:00487-2021. [PMID: 34881331 PMCID: PMC8646005 DOI: 10.1183/23120541.00487-2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/04/2021] [Indexed: 11/30/2022] Open
Abstract
Multiple-breath nitrogen washout (MBNW) is an emerging clinical test for assessing ventilation heterogeneity [1], often characteristically increased in asthma. MBNW indices both indicate and predict response to asthma treatment [2–4], and therefore may be an important tool for guiding treatment decisions [2]. Two established breathing protocols are currently in use: 1-L tidal volume (VT) controlled breathing (CB) [5, 6] and unrestricted free breathing (FB) [7]. The CB protocol requires targeted VT and respiratory rate, whereas the FB protocol encourages relaxed tidal breathing, making it more suitable for paediatrics [8]. Two recently published studies in healthy adults showed that indices of conductive and acinar ventilation heterogeneity (Scond and Sacin, respectively) and, to a lesser extent, lung clearance index (LCI), were not comparable between breathing protocols [9, 10]. Importantly, differences between the protocols were dependent on the magnitude of ventilation heterogeneity. Thus, the assumption is that these effects would be amplified in disease, where ventilation heterogeneity is greater and clinical utility is most relevant. However, this has not been confirmed to date. We hypothesised that people with asthma, where ventilation heterogeneity is greater, would exhibit greater differences between the two protocols than the differences seen in healthy adults. The lack of comparability in indices of ventilation heterogeneity between free- and controlled-breathing MBNW protocols is confirmed in asthmahttps://bit.ly/3lmri4A
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Affiliation(s)
- Blake M Handley
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia.,These first authors contributed equally
| | - Jack Bozier
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia.,These first authors contributed equally
| | - Edward Jeagal
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,University of Technology Sydney, School of Life Sciences, Sydney, NSW, Australia
| | - Sandra Rutting
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Robin E Schoeffel
- Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Paul D Robinson
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,Dept of Respiratory Medicine, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Gregory G King
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Stephen Milne
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,Centre for Heart Lung Innovation, St Paul's Hospital and Division of Respiratory Medicine, University of British Columbia, Vancouver, BC, Canada.,These senior authors contributed equally
| | - Cindy Thamrin
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,These senior authors contributed equally
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An Analysis on the Performance of a Mobile Platform with Gas Sensors for Real Time Victim Localization. SENSORS 2021; 21:s21062018. [PMID: 33809293 PMCID: PMC7999499 DOI: 10.3390/s21062018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 02/27/2021] [Accepted: 03/05/2021] [Indexed: 11/17/2022]
Abstract
This work concerns the performance analysis of the sensors contained in a victim detection system. The system is a mobile platform with gas sensors utilized for real time victim localization in urban environments after a disaster has caused the entrapment of people in partially collapsed building structures. The operating principle of the platform is the sampling of air from potential survival spaces (voids) and the measurement of the sampled air's temperature and concentration of CO2 and O2. Humans in a survival space are modelled as sources of CO2 and heat and sinks of O2. The physical openings of a survival space are modelled as sources of fresh air and sinks of the internal air. These sources and sinks dynamically affect the monitored properties of the air inside a survival space. In this paper, the effects of fresh air sources and internal air sinks are first examined in relation to local weather conditions. Then, the effect of human sources of CO2 and sinks of O2 in the space are examined. A model is formulated in order to reliably estimate the concentration of CO2 and O2 as a function of time for given reasonable entrapment scenarios. The input parameters are the local weather conditions, the openings of the survival space, and the number and type of entrapped humans. Three different tests successfully verified the presented theoretical estimations. A detection system with gas sensors of specified or measured capabilities, by utilizing this model and based on the expected concentrations, may inform the operator of the minimum required presence of humans in a survival space that can be detected after "some time".
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Kentgens AC, Latzin P, Yammine S. Fixed breathing protocols in multiple-breath-washout testing: truly an option in children? Eur Respir J 2021; 57:57/3/2100001. [PMID: 33664101 DOI: 10.1183/13993003.00001-2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Accepted: 01/03/2021] [Indexed: 11/05/2022]
Affiliation(s)
- Anne-Christianne Kentgens
- Division of Respiratory Medicine, Dept of Pediatrics, Inselspital, University of Bern, Bern, Switzerland
| | - Philipp Latzin
- Division of Respiratory Medicine, Dept of Pediatrics, Inselspital, University of Bern, Bern, Switzerland
| | - Sophie Yammine
- Division of Respiratory Medicine, Dept of Pediatrics, Inselspital, University of Bern, Bern, Switzerland
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Handley BM, Jeagal E, Schoeffel RE, Badal T, Chapman DG, Farrow CE, King GG, Robinson PD, Milne S, Thamrin C. Controlled versus free breathing for multiple breath nitrogen washout in healthy adults. ERJ Open Res 2021; 7:00435-2020. [PMID: 33532457 PMCID: PMC7836463 DOI: 10.1183/23120541.00435-2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/16/2020] [Indexed: 11/18/2022] Open
Abstract
Multiple breath nitrogen washout (MBNW) quantifies ventilation heterogeneity. Two distinct protocols are currently used for MBNW testing: “controlled breathing”, with targeted tidal volume (VT) and respiratory rate (RR); and “free breathing”, with no constraints on breathing pattern. Indices derived from the two protocols (functional residual capacity (FRC), lung clearance index (LCI), Scond, Sacin) have not been directly compared in adults. We aimed to determine whether MBNW indices are comparable between protocols, to identify factors underlying any between-protocol differences and to determine the between-session variabilities of each protocol. We performed MBNW testing by both protocols in 27 healthy adult volunteers, applying the currently proposed correction for VT to Scond and Sacin derived from free breathing. To establish between-session variability, we repeated testing in 15 volunteers within 3 months. While FRC was comparable between controlled versus free breathing (3.17 (0.98) versus 3.18 (0.94) L, p=0.88), indices of ventilation heterogeneity derived from the two protocols were not, with poor correlation for Scond (r=0.18, p=0.36) and significant bias for Sacin (0.057 (0.021) L−1versus 0.085 (0.038) L−1, p=0.0004). Between-protocol differences in Sacin were related to differences in the breathing pattern, i.e. VT (p=0.004) and RR (p=0.01), rather than FRC. FRC and LCI showed good between-session repeatability, but Scond and Sacin from free breathing showed poor repeatability with wide limits of agreement. These findings have implications for the ongoing clinical implementation of MBNW, as they demonstrate that Scond and Sacin from free breathing, despite VT correction, are not equivalent to the controlled breathing protocol. The poor between-session repeatability of Scond during free breathing may limit its clinical utility. Phase 3 slopes indices derived from “free breathing” and “controlled breathing” MBNW protocols are not comparable, and differences are related to breathing patterns. These findings have implications for the ongoing clinical implementation of MBNW.https://bit.ly/35oQYnW
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Affiliation(s)
- Blake M Handley
- Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia.,Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia
| | - Edward Jeagal
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia
| | - Robin E Schoeffel
- Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia
| | - Tanya Badal
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia
| | - David G Chapman
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,Translational Airways Group, School of Life Sciences, Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - Catherine E Farrow
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,Dept of Respiratory and Sleep Medicine, Westmead Hospital, Westmead, NSW, Australia
| | - Gregory G King
- Dept of Respiratory Medicine, Royal North Shore Hospital, St Leonards, NSW, Australia.,Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,Faculty of Medicine and Health, University of Sydney, Camperdown, NSW, Australia
| | - Paul D Robinson
- Dept of Respiratory Medicine, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Stephen Milne
- Faculty of Medicine and Health, University of Sydney, Camperdown, NSW, Australia.,Centre for Heart Lung Innovation, St Paul's Hospital and Division of Respiratory Medicine, University of British Columbia, Vancouver, BC, Canada.,These authors contributed equally
| | - Cindy Thamrin
- Woolcock Institute of Medical Research, University of Sydney, Glebe, NSW, Australia.,Faculty of Medicine and Health, University of Sydney, Camperdown, NSW, Australia.,These authors contributed equally
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7
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Motta-Ribeiro GC, Winkler T. Breathing freely during nitrogen washout. J Appl Physiol (1985) 2020; 129:1150-1151. [PMID: 33090907 DOI: 10.1152/japplphysiol.00847.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Gabriel C Motta-Ribeiro
- Biomedical Engineering Programme, COPPE, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Tilo Winkler
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
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Verbanck S, Schuermans D, Paiva M, Robinson PD, Vanderhelst E. Mitigating increased variability of multiple breath washout indices due to tidal breathing. Eur Respir J 2020; 57:13993003.02765-2020. [PMID: 32994196 DOI: 10.1183/13993003.02765-2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 09/14/2020] [Indexed: 11/05/2022]
Affiliation(s)
- Sylvia Verbanck
- Respiratory Division, University Hospital UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium
| | - Daniel Schuermans
- Respiratory Division, University Hospital UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium
| | - Manuel Paiva
- Respiratory Division, University Hospital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Paul D Robinson
- Dept of Respiratory Medicine, The Children's Hospital at Westmead, Sydney, Australia
| | - Eef Vanderhelst
- Respiratory Division, University Hospital UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium
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