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Intercostal muscle oxygenation and expiratory loaded breathing at rest: Respiratory pattern effect. Respir Physiol Neurobiol 2022; 304:103925. [PMID: 35662640 DOI: 10.1016/j.resp.2022.103925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 05/24/2022] [Accepted: 05/29/2022] [Indexed: 11/21/2022]
Abstract
In patients with airway obstruction, an increase in breathing frequency at rest is commonly associated with a dynamic hyperinflation (DH). In such a situation, intercostal muscle oxygenation may be disturbed. This hypothesis was examined in a context of simulated airway obstruction in healthy subjects. After a control period of 5 min, twelve participants (20 ± 2 years) breathed at rest through a 20-cmH2O expiratory threshold load, either by increasing or reducing their respiratory rate (ETLF+ or ETLF). Tissue saturation index (TSI) and concentration changes in oxyhaemoglobin (oxy[Hb+Mb]) were measured as well as cardiorespiratory variables. Inspiratory capacity was decreased in ETLF+ (p < 0.001) and correlated with dyspnea. An increase in oxy[Hb+Mb] occurred in ETLF+ that was higher than in ETLF (p < 0.01). TSI was not different between conditions. In healthy subjects at rest, an increase in respiratory rate during a simulated obstruction with an expiratory threshold load resulted in paradoxical response with DH emergence while intercostal muscle oxygenation was preserved.
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Sakkatos P, Bruton A, Barney A. Changes in quantifiable breathing pattern components predict asthma control: an observational cross-sectional study. Asthma Res Pract 2021; 7:5. [PMID: 33823934 PMCID: PMC8022412 DOI: 10.1186/s40733-021-00071-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 03/28/2021] [Indexed: 11/25/2022] Open
Abstract
Background Breathing pattern disorders are frequently reported in uncontrolled asthma. At present, this is primarily assessed by questionnaires, which are subjective. Objective measures of breathing pattern components may provide additional useful information about asthma control. This study examined whether respiratory timing parameters and thoracoabdominal (TA) motion measures could predict and classify levels of asthma control. Methods One hundred twenty-two asthma patients at STEP 2- STEP 5 GINA asthma medication were enrolled. Asthma control was determined by the Asthma Control Questionnaire (ACQ7-item) and patients divided into ‘well controlled’ or ‘uncontrolled’ groups. Breathing pattern components (respiratory rate (RR), ratio of inspiration duration to expiration duration (Ti/Te), ratio of ribcage amplitude over abdominal amplitude during expiration phase (RCampe/ABampe), were measured using Structured Light Plethysmography (SLP) in a sitting position for 5-min. Breath-by-breath analysis was performed to extract mean values and within-subject variability (measured by the Coefficient of Variance (CoV%). Binary multiple logistic regression was used to test whether breathing pattern components are predictive of asthma control. A post-hoc analysis determined the discriminant accuracy of any statistically significant predictive model. Results Fifty-nine out of 122 asthma patients had an ACQ7-item < 0.75 (well-controlled asthma) with the rest being uncontrolled (n = 63). The absolute mean values of breathing pattern components did not predict asthma control (R2 = 0.09) with only mean RR being a significant predictor (p < 0.01). The CoV% of the examined breathing components did predict asthma control (R2 = 0.45) with all predictors having significant odds ratios (p < 0.01). The ROC curve showed that cut-off points > 7.40% for the COV% of the RR, > 21.66% for the CoV% of Ti/Te and > 18.78% for the CoV% of RCampe/ABampe indicated uncontrolled asthma. Conclusion The within-subject variability of timing parameters and TA motion can be used to predict asthma control. Higher breathing pattern variability was associated with uncontrolled asthma suggesting that irregular resting breathing can be an indicator of poor asthma control.
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Affiliation(s)
| | - Anne Bruton
- School of Health Sciences, University of Southampton, Southampton, UK
| | - Anna Barney
- Institute for Sound and Vibration Research, University of Southampton, Southampton, UK
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Lynch JJ, Rossignol E, Moehrle JJ, Van Vleet TR, Marsh KC, Parman T, Mirsalis J, Ottinger SE, Segreti JA, Rao M, Mittelstadt SW. Increased stress associated with head-out plethysmography testing can exacerbate respiratory effects and lead to mortality in rats. J Pharmacol Toxicol Methods 2019; 99:106580. [PMID: 31085318 DOI: 10.1016/j.vascn.2019.106580] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 04/22/2019] [Accepted: 05/03/2019] [Indexed: 01/27/2023]
Abstract
INTRODUCTION DSM421, a dihydroorotate dehydrogenase inhibitor, was in preclinical development as a potential treatment option for malaria. When tested in a core battery of safety pharmacology assays, DSM421 did not produce any effects at oral doses up to 750 mg/kg in an Irwin test in rats, but a respiratory study in rats using head-out plethysmography resulted in substantial changes in respiratory function as well as moribundity and mortality at that and lower doses. An investigation was performed to determine the source of this discrepancy. METHODS Potential testing errors, differences in types of plethysmography testing chambers, effects on stress indicators, and off-target activity were investigated. RESULTS Respiratory changes and toxicity (resulting in euthanasia in extremis) were confirmed in a repeat, head-out plethysmography test, but the effects of DSM421 were much less severe overall when the rats were tested in whole-body chambers. Additionally, at the end of the 5-h post-dosing respiratory monitoring periods, levels of stress-related hormones (particularly corticosterone) were higher overall in the head-out, than in the whole-body, tested rats. Furthermore, DSM421 was found to produce changes in cardiovascular function in unrestrained rats, and it was shown to have off-target binding affinity at the adenosine A3 receptor (which is associated with bronchoconstriction). DISCUSSION The generalized stress inherent to head-out plethysmography testing exacerbated the respiratory effects of DSM421 and was possibly compounded by DSM421's cardiovascular effects, thus artifactually resulting in moribundity and mortality in rats. Care should be taken when choosing whether to use head-out versus whole-body plethysmography chambers during respiratory function testing in animals.
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Affiliation(s)
- James J Lynch
- AbbVie, Inc., 1 North Waukegan Road, North Chicago, IL 60064, USA.
| | - Emilie Rossignol
- Medicines for Malaria Venture, P.O. Box 1826, 20, Route de Pré-Bois, 1215, Geneva 15, Switzerland
| | - Joerg J Moehrle
- Medicines for Malaria Venture, P.O. Box 1826, 20, Route de Pré-Bois, 1215, Geneva 15, Switzerland
| | | | - Kennan C Marsh
- AbbVie, Inc., 1 North Waukegan Road, North Chicago, IL 60064, USA
| | - Toufan Parman
- SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA
| | - Jon Mirsalis
- SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025, USA
| | - Sean E Ottinger
- Takeda Pharmaceutical International Co., 35 Landsdowne St, Cambridge, MA 01239, USA
| | - Jason A Segreti
- AbbVie, Inc., 1 North Waukegan Road, North Chicago, IL 60064, USA
| | - Mohan Rao
- AbbVie, Inc., 1 North Waukegan Road, North Chicago, IL 60064, USA
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MacBean V, Pringle CL, Lunt AC, Sharp KD, Ali A, Greenough A, Moxham J, Rafferty GF. Parasternal intercostal muscle activity during methacholine-induced bronchoconstriction. Exp Physiol 2017; 102:475-484. [PMID: 28194830 DOI: 10.1113/ep086120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 02/08/2017] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? The parasternal intercostal electromyogram (EMGpara) is known to provide an accurate, non-invasive index of respiratory load-capacity balance. Although relationships between EMGpara and both airflow obstruction and hyperinflation have been shown, the independent contribution of each factor has not been examined. What is the main finding and its importance? Reductions in airway calibre and inspiratory capacity along with increases in EMGpara were induced via methacholine challenge. A strong inverse relationship was observed between EMGpara and airway obstruction, with no influence of inspiratory capacity. These data suggest that EMGpara is more strongly influenced by airway calibre than by changes in end-expiratory lung volume during airway challenge testing. Neural respiratory drive, measured via the parasternal intercostal electromyogram (EMGpara), provides a non-invasive index of the load-capacity balance of the respiratory muscle pump. Previous studies in patients with obstructive lung disease have shown strong relationships between EMGpara and the extent of both airflow obstruction and hyperinflation. The relative influence of the two factors has not, however, been described. Airflow obstruction was induced via methacholine challenge testing in 25 adult humans. Forced expiratory volume in 1 s (FEV1 ) and surface EMGpara during tidal breathing were measured after each dose, with 20 of the participants also undergoing measurements of inspiratory capacity (IC) at each stage. Linear mixed model analysis was used to assess dose-wise changes in FEV1 and EMGpara, and thereafter to determine the influence of changes in FEV1 and IC on change in EMGpara. Median (interquartile range) FEV1 decreased significantly [from 96.00 (80.00-122.30) to 67.80 (37.98-92.27)% predicted, P < 0.0001] and EMGpara increased significantly [from 5.37 (2.25-8.92) to 6.27 (3.37-19.60) μV, P < 0.0001] from baseline to end of test. Linear mixed model analysis showed a significant interaction between methacholine dose and induced change in EMGpara, with an increase in EMGpara of 0.24 (95% confidence interval 0.11-0.37) μV per methacholine dose2 . Change in FEV1 further influenced this relationship [increase in slope of 0.002 (0.004-0.001) μV dose-2 per % predicted fall in FEV1 , P = 0.011], but not with change in IC. These data suggest that bronchoconstriction exerts a more potent influence on levels of EMGpara than changes in end-expiratory lung volume during methacholine challenge.
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Affiliation(s)
- Victoria MacBean
- Division of Asthma, Allergy and Lung Biology, King's College London, London, UK
| | - Claire L Pringle
- Division of Asthma, Allergy and Lung Biology, King's College London, London, UK
| | - Alan C Lunt
- Division of Asthma, Allergy and Lung Biology, King's College London, London, UK
| | - Keith D Sharp
- Division of Asthma, Allergy and Lung Biology, King's College London, London, UK
| | - Ashraf Ali
- Department of Respiratory Medicine, King's College Hospital NHS Foundation Trust, London, UK
| | - Anne Greenough
- Division of Asthma, Allergy and Lung Biology, King's College London, London, UK.,National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London, London, UK
| | - John Moxham
- Division of Asthma, Allergy and Lung Biology, King's College London, London, UK
| | - Gerrard F Rafferty
- Division of Asthma, Allergy and Lung Biology, King's College London, London, UK
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