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Chuang ML. Analyzing key elements of breathing patterns, deriving remaining variables, and identifying cutoff values in individuals with chronic respiratory disease and healthy subjects. Respir Physiol Neurobiol 2024; 324:104242. [PMID: 38432595 DOI: 10.1016/j.resp.2024.104242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 02/05/2024] [Accepted: 02/25/2024] [Indexed: 03/05/2024]
Abstract
BACKGROUND Pulmonary physiology encompasses intricate breathing patterns (BPs), characterized by breathing frequency (Bf), volumes, and flows. The complexities intensify in the presence of interstitial lung disease (ILD) and chronic obstructive pulmonary disease (COPD), especially during exercise. This study seeks to identify pivotal factors driving changes among these variables and establish cutoff values, comparing their efficacy in differentiating BPs to traditional methods, specifically a breathing reserve (BR) of 30% and a Bf of 50 bpm. METHODS Screening 267 subjects revealed 23 with ILD, 126 with COPD, 33 healthy individuals, and the exclusion of 85 subjects. Lung function tests and ramp-pattern cardiopulmonary exercise testing (CPET) were conducted, identifying crucial BP elements. Changes were compared between groups at peak exercise. The area under the receiver operating characteristic curve (AUC) analysis determined cutoff values. RESULTS Inspiratory time (TI) remained constant at peak exercise for all subjects (two-group comparisons, all p=NS). Given known differences in expiratory time (TE) and tidal volume (VT) among ILD, COPD, and healthy states, constant TI could infer patterns for Bf, total breathing cycle time (TTOT=60/Bf), I:E ratio, inspiratory duty cycle (IDC, TI/TTOT), rapid shallow breathing index (Bf/VT), tidal inspiratory and expiratory flows (VT/TI and VT/TE), and minute ventilation (V̇E=Bf×VT) across conditions. These inferences aligned with measurements, with potential type II errors causing inconsistencies. RSBI of 23 bpm/L and VT/TI of 104 L/min may differentiate ILD from control, while V̇E of 54 L/min, BR of 30%, and VT/TE of 108 may differentiate COPD from control. BR of 21%, TE of 0.99 s, and IDC of .45 may differentiate ILD from COPD. The algorithm outperformed traditional methods (AUC 0.84-0.91 versus 0.59-0.90). CONCLUSION The quasi-fixed TI, in conjunction with TE and VT, proves effective in inferring time-related variables of BPs. The findings have the potential to significantly enhance medical education in interpreting cardiopulmonary exercise testing. Moreover, the study introduces a novel algorithm for distinguishing BPs among individuals with ILD, COPD, and those who are healthy.
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Affiliation(s)
- Ming-Lung Chuang
- Division of Pulmonary Medicine and Department of Internal Medicine, Chung Shan Medical University Hospital, Taichung 40201, Taiwan, ROC; School of Medicine, Chung Shan Medical University, Taichung 40201, Taiwan, ROC.
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Evaluation of primary and accessory respiratory muscles and their influence on exercise capacity and dyspnea in pulmonary arterial hypertension. Heart Lung 2023; 57:173-179. [PMID: 36219922 DOI: 10.1016/j.hrtlng.2022.09.015] [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: 07/08/2022] [Revised: 08/11/2022] [Accepted: 09/25/2022] [Indexed: 11/05/2022]
Abstract
BACKGROUND Skeletal and respiratory muscle disfunction has been described in pulmonary arterial hypertension (PAH), however, involvement of accessory respiratory muscles and their association with symptomatology in PAH is unclear. OBJECTIVES To assess the primary and accessory respiratory muscles and their influence on exercise tolerance and dyspnea. METHODS 27 patients and 27 healthy controls were included. Serratus anterior (SA), pectoralis muscles (PM) and sternocleidomastoid (SCM) muscle strength were evaluated as accessory respiratory muscles, maximal inspiratory (MIP) and expiratory pressures (MEP) as primary respiratory muscles, and quadriceps as peripheral muscle. Exercise capacity was evaluated with 6-min walk test (6MWT), dyspnea with modified Medical Council Research (MMRC) and London Chest Activity of Daily Living (LCADL) scales. RESULTS All evaluated muscles, except SCM, and 6MWT were decreased in patient group (p < 0.01). SA was the most affected muscle among primary and accessory respiratory muscles (Cohen's-d = 1.35). All evaluated muscles significantly correlated to 6MWT (r = 0.428-0.525). A multivariate model including SA, SCM and MIP was the best model for predicting 6MWT (R = 0.606; R2 = 0.368; p = 0.013) and SA strength had the most impact on the 6MWT (B = 1.242; β = 0.340). None of the models including respiratory muscles were able to predict dyspnea, however PM and SA strength correlated to LCADL total (r = -0.493) and MMRC (r = -0.523), respectively. CONCLUSION SCM may be excessively used in PAH since it retains its strength. Considering the relationship of accessory respiratory muscles with exercise tolerance and dyspnea, monitoring the strength of these muscles in the clinical practice may help providing better management for PAH.
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Van Hollebeke M, Poddighe D, Clerckx B, Muller J, Hermans G, Gosselink R, Langer D, Louvaris Z. High-Intensity Inspiratory Muscle Training Improves Scalene and Sternocleidomastoid Muscle Oxygenation Parameters in Patients With Weaning Difficulties: A Randomized Controlled Trial. Front Physiol 2022; 13:786575. [PMID: 35222072 PMCID: PMC8864155 DOI: 10.3389/fphys.2022.786575] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 01/04/2022] [Indexed: 11/13/2022] Open
Abstract
BackgroundCritically ill patients who have difficulties weaning from the mechanical ventilator are prone to develop respiratory muscle weakness. Inspiratory muscle training (IMT) can improve respiratory muscle strength. Whether IMT can improve scalene and sternocleidomastoid muscle oxygenation parameters is unknown.AimTo compare changes in muscle oxygenation parameters of scalene and sternocleidomastoid inspiratory muscles during a standardized task between patients with weaning difficulties who received either high-intensity IMT (intervention) or sham low-intensity IMT (control).MethodForty-one patients performed daily IMT sessions (4 sets, 6–10 breaths) until weaning success or for 28 consecutive days. The training load was progressively adjusted in the intervention group (n = 22) to the highest tolerable load, whilst the control group (n = 19) kept training at 10% of their baseline maximal inspiratory pressure (PImax). Breathing characteristics (i.e., work and power of breathing, PoB), respiratory muscle function [i.e., PImax and forced vital capacity (FVC)] were measured during a standardized loaded breathing task against a load of 30% of baseline PImax before and after the IMT period. In addition, during the same loaded breathing task, absolute mean and nadir changes from baseline in local scalene and sternocleidomastoid muscle oxygen saturation index (Δ%StiO2) (an index of oxygen extraction) and nadir Δ%StiO2 normalized for the PoB were measured by near-infrared spectroscopy.ResultsAt post measures, only the intervention group improved mean PoB compared to pre measures (Pre: 0.42 ± 0.33 watts, Post: 0.63 ± 0.51watts, p-value < 0.01). At post measures, both groups significantly improved nadir scalene muscles StiO2% normalized for the mean PoB (ΔStiOnadir%/watt) compared to pre measurements and the improvement was not significant different between groups (p-value = 0.40). However, at post measures, nadir sternocleidomastoid muscle StiO2% normalized for the mean PoB (ΔStiOnadir%/watt) was significantly greater improved in the intervention group (mean difference: +18.4, 95%CI: −1.4; 38.1) compared to the control group (mean difference: +3.7, 95%CI: −18.7; 26.0, between group p-value < 0.01). Both groups significantly improved PImax (Intervention: +15 ± 13 cmH2O p-value < 0.01, Control: +13 ± 15 cmH2O p-value < 0.01). FVC only significantly improved in the intervention group (+0.33 ± 0.31 L p < 0.01) report also change in control group.ConclusionThis exploratory study suggests that high-intensity IMT induces greater improvements in scalene and sternocleidomastoid muscle oxygenation parameters attributed for oxygen delivery, utilization and oxygen saturation index compared to low-intensity IMT in patients with weaning difficulties.
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Affiliation(s)
- Marine Van Hollebeke
- Faculty of Movement and Rehabilitation Sciences, Department of Rehabilitation Sciences, Research Group for Rehabilitation in Internal Disorders, KU Leuven, Leuven, Belgium
- Department of Intensive Care Medicine, University Hospitals Leuven, Leuven, Belgium
- *Correspondence: Marine Van Hollebeke,
| | - Diego Poddighe
- Faculty of Movement and Rehabilitation Sciences, Department of Rehabilitation Sciences, Research Group for Rehabilitation in Internal Disorders, KU Leuven, Leuven, Belgium
- Department of Intensive Care Medicine, University Hospitals Leuven, Leuven, Belgium
| | - Beatrix Clerckx
- Department of Intensive Care Medicine, University Hospitals Leuven, Leuven, Belgium
| | - Jan Muller
- Department of Intensive Care Medicine, University Hospitals Leuven, Leuven, Belgium
| | - Greet Hermans
- Department of Intensive Care Medicine, University Hospitals Leuven, Leuven, Belgium
- Laboratory of Intensive Care Medicine, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Rik Gosselink
- Faculty of Movement and Rehabilitation Sciences, Department of Rehabilitation Sciences, Research Group for Rehabilitation in Internal Disorders, KU Leuven, Leuven, Belgium
- Department of Intensive Care Medicine, University Hospitals Leuven, Leuven, Belgium
| | - Daniel Langer
- Faculty of Movement and Rehabilitation Sciences, Department of Rehabilitation Sciences, Research Group for Rehabilitation in Internal Disorders, KU Leuven, Leuven, Belgium
- Department of Intensive Care Medicine, University Hospitals Leuven, Leuven, Belgium
| | - Zafeiris Louvaris
- Faculty of Movement and Rehabilitation Sciences, Department of Rehabilitation Sciences, Research Group for Rehabilitation in Internal Disorders, KU Leuven, Leuven, Belgium
- Department of Intensive Care Medicine, University Hospitals Leuven, Leuven, Belgium
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Miki K, Tsujino K, Maekuara R, Matsuki T, Miki M, Hashimoto H, Kagawa H, Kawasaki T, Kuge T, Kida H. Oxygen Extraction Based on Inspiratory and Expiratory Gas Analysis Identifies Ventilatory Inefficiency in Chronic Obstructive Pulmonary Disease. Front Physiol 2021; 12:703977. [PMID: 34393822 PMCID: PMC8355815 DOI: 10.3389/fphys.2021.703977] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 06/18/2021] [Indexed: 12/28/2022] Open
Abstract
Aims: In contrast to cardiovascular disease, low rather than high ventilatory inefficiency, evaluated by the minute ventilation-carbon dioxide output (V'E-V'CO2)-slope, has been recognized as being related to greater disease severity in chronic obstructive pulmonary disease (COPD). To better care for patients with cardiopulmonary disease, understanding the physiological correlation between ventilatory inefficiency and exercise limitation is necessary, but remains inadequate. Given that oxygen uptake (V'O2) evaluated by cardiopulmonary exercise testing (CPET) depends on both the ventilatory capability and oxygen extraction, i.e., the difference between inspiratory and expiratory oxygen concentration (ΔFO2), the aim of this study was to investigate the correlations between V'E-V'CO2-slope and the ΔFO2 during exercise and their physiological implications in patients with COPD. Methods: A total of 156 COPD patients (mean age, 70.9 ± 7.2 years) with Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages I–IV and 16 controls underwent CPET with blood gas analysis. Results: With the progression of COPD, mechanical ventilatory constraints together with a slower respiratory frequency led to exertional respiratory acidosis. In GOLD IV cases, (1) decrease in the dependence of reduced peak V'O2 on V'E led to an increase in its dependence on peak ΔFO2 during exercise; and (2) the ΔFO2-V'CO2-slope became steeper, correlating with the severity of exertional respiratory acidosis (r = 0.6359, p < 0.0001). No significant differences in peak exercise ΔFO2 or V'E-V'CO2-slope were observed among the various GOLD stages. In all subjects, including controls, peak exercise ΔFO2 had the strongest correlation with the V'E-V'CO2-slope (r = −0.8835, p < 0.0001) and correlated well with body mass index (r = 0.3871, p < 0.0001), although it did not correlate with the heart rate-V'CO2-relationship and V'E. Conclusions: Ventilatory efficiency related to CO2 clearance might depend on exertional oxygen extraction in the body. Measuring ΔFO2 might be a key component for identifying ventilatory inefficiency and oxygen availability. Increasing ΔFO2 would help to improve ventilatory inefficiency and exercise tolerance separately from cardiac and ventilatory capability in COPD patients.
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Affiliation(s)
- Keisuke Miki
- Department of Respiratory Medicine, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, Japan
| | - Kazuyuki Tsujino
- Department of Respiratory Medicine, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, Japan
| | - Ryoji Maekuara
- Graduate School of Health Care Sciences, Jikei Institute, Osaka, Japan
| | - Takanori Matsuki
- Department of Respiratory Medicine, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, Japan
| | - Mari Miki
- Department of Respiratory Medicine, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, Japan
| | - Hisako Hashimoto
- Department of Respiratory Medicine, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, Japan
| | - Hiroyuki Kagawa
- Department of Respiratory Medicine, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, Japan
| | - Takahiro Kawasaki
- Department of Respiratory Medicine, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, Japan
| | - Tomoki Kuge
- Department of Respiratory Medicine, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, Japan
| | - Hiroshi Kida
- Department of Respiratory Medicine, National Hospital Organization Osaka Toneyama Medical Center, Toyonaka, Japan
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Istfan R, Gómez CA, Applegate M, Rozenberg D, Reid WD, Roblyer D. Hemodynamics of the sternocleidomastoid measured with frequency domain near-infrared spectroscopy towards non-invasive monitoring during mechanical ventilation. BIOMEDICAL OPTICS EXPRESS 2021; 12:4147-4162. [PMID: 34457405 PMCID: PMC8367268 DOI: 10.1364/boe.430423] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 06/05/2021] [Accepted: 06/08/2021] [Indexed: 06/13/2023]
Abstract
Mechanical ventilation (MV) is used to assist spontaneous breathing in critically ill patients in the intensive care unit (ICU). MV is a cornerstone of critical care medicine but it is now known that inspiratory muscle dysfunction due to injury, disuse, and/or atrophy during MV plays a major role in outcomes for these patients. For example, prolonged MV is strongly correlated with dysfunction of the sternocleidomastoid (SCM), an accessory inspiratory muscle that has been linked to weaning failure from MV. Hemodynamic monitoring of the SCM may provide an important non-invasive and real-time means to monitor MV. In this work, we first conducted multi-layer Monte Carlo simulations to confirm the ability of near infrared light to detect changes in the oxygenation of the SCM over wide ranges of skin tones and adipose layer thicknesses. We then optimized a custom digital frequency domain near-infrared spectroscopy (FD-NIRS) system for continuous 10 Hz measurements of the SCM at 730 nm and 850 nm. A healthy volunteer study was conducted (N=10); subjects performed sets of isometric neck flexions of the SCM. Substantial changes in oxyhemoglobin + oxymyoglobin (oxy[Hb + Mb]), deoxyhemoglobin + deoxymyoglobin (deoxy[Hb + Mb]), and total hemoglobin + myoglobin (total[Hb + Mb]) were observed during sustained and intermittent isometric flexions. There were notable sex differences observed in the magnitude of hemodynamic changes (∼2x larger changes in males for oxy[Hb + Mb] and deoxy[Hb + Mb]). The magnitude of hemodynamic changes when taking into account µs' changes during flexions was ∼ 2-2.5x larger as compared to assuming constant scattering (CS), which is a common assumption used for continuous wave (CW) NIRS methods. This study suggests that FD-NIRS provides improved accuracy for hemodynamic monitoring of the SCM compared to CW-NIRS, and that FD-NIRS may provide value for SCM monitoring during MV.
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Affiliation(s)
- Raeef Istfan
- Department of Biomedical Engineering, Boston University, Boston, MA 02125, USA
| | - Carlos A. Gómez
- Department of Biomedical Engineering, Boston University, Boston, MA 02125, USA
| | - Matthew Applegate
- Department of Biomedical Engineering, Boston University, Boston, MA 02125, USA
| | - Dmitry Rozenberg
- Department of Medicine, Respirology and Lung Transplantation, University Health Network, University of Toronto, Toronto, ON, Canada
| | - W. Darlene Reid
- Department of Physical Therapy, University of Toronto, Toronto ON, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, ON, Canada
- KITE - Toronto Rehabilitation Institute, University Health Network, Toronto, ON, Canada
| | - Darren Roblyer
- Department of Biomedical Engineering, Boston University, Boston, MA 02125, USA
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Theodorakopoulou MP, Bakaloudi DR, Dipla K, Zafeiridis A, Boutou AK. Vascular endothelial damage in COPD: current functional assessment methods and future perspectives. Expert Rev Respir Med 2021; 15:1121-1133. [PMID: 33874819 DOI: 10.1080/17476348.2021.1919089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Introduction: Cardiovascular disease is a major cause of death in chronic obstructive pulmonary disease (COPD), but the relationship between these two entities is not fully understood; smoking, inflammation, arterial stiffness and endothelial dysfunction are significant determinants. Endothelial dysfunction is not only associated with cardiovascular disease, but also with COPD severity.Areas covered: Several functional methods have been developed to evaluate endothelial function in healthy and diseased individuals; from the invasive angiography of epicardial coronary arteries and Venous-Occlusion-Plethysmography, to more modern, noninvasive approaches such as Flow-Mediated-Dilatation, Peripheral-Arterial-Tonometry and Near-Infrared-Spectroscopy, all these methods have boosted clinical research in this field. In this context, this narrative review, which included articles published in PubMed and Scopus up to 25-November-2020, summarizes available functional methods for endothelial damage assessment in COPD and discusses existing evidence on their associations with comorbidities and outcomes in this population.Expert opinion: Accumulated evidence suggests that endothelial dysfunction occurs in early stages of CΟPD and worsens with pulmonary obstruction severity and during acute exacerbations. Novel methods evaluating endothelial function offer a detailed, real-time assessment of different parameters related to vascular function and should be increasingly used to shed more light on the role of endothelial damage on cardiovascular and COPD progression.
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Affiliation(s)
- Marieta P Theodorakopoulou
- Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Dimitra Rafailia Bakaloudi
- Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Konstantina Dipla
- Exercise Physiology & Biochemistry Laboratory, Department of Sport Sciences at Serres, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Andreas Zafeiridis
- Exercise Physiology & Biochemistry Laboratory, Department of Sport Sciences at Serres, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Afroditi K Boutou
- Department of Respiratory Medicine, G. Papanikolaou Hospital, Thessaloniki, Greece
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Miles M, Rodrigues A, Tajali S, Xiong Y, Orchanian-Cheff A, Reid WD, Rozenberg D. Muscle and cerebral oxygenation during cycling in chronic obstructive pulmonary disease: A scoping review. Chron Respir Dis 2021; 18:1479973121993494. [PMID: 33605155 PMCID: PMC7897842 DOI: 10.1177/1479973121993494] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
To synthesize evidence for prefrontal cortex (PFC), quadriceps, and respiratory muscle oxygenation using near-infrared spectroscopy (NIRS) during cycling in individuals with chronic obstructive pulmonary disease (COPD). A scoping review was performed searching databases (inception-August 2020): Ovid MEDLINE, EMBASE, Cochrane Systematic Reviews, Cochrane Central Register of Controlled Clinical Trials, CINAHL, SPORTDiscus and Pedro. The search focused on COPD, cycling, and NIRS outcomes. 29 studies (541 COPD participants) were included. Compared to healthy individuals (8 studies), COPD patients at lower cycling workloads had more rapid increases in vastus lateralis (VL) deoxygenated hemoglobin (HHb); lower increases in VL total hemoglobin (tHb) and blood flow; and lower muscle tissue saturation (StO2). Heliox and bronchodilators were associated with smaller and slower increases in VL HHb. Heliox increased VL and intercostal blood flow compared to room air and supplemental oxygen in COPD patients (1 study). PFC oxygenated hemoglobin (O2Hb) increased in COPD individuals during cycling in 5 of 8 studies. Individuals with COPD and heart failure demonstrated worse VL and PFC NIRS outcomes compared to patients with only COPD-higher or more rapid increase in VL HHb and no change or decrease in PFC O2Hb. Individuals with COPD present with a mismatch between muscle oxygen delivery and utilization, characterized by more rapid increase in VL HHb, lower muscle O2Hb and lower muscle StO2. PFC O2Hb increases or tends to increase in individuals with COPD during exercise, but this relationship warrants further investigation. NIRS can be used to identify key deoxygenation thresholds during exercise to inform PFC and muscle oxygenation.
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Affiliation(s)
- Melissa Miles
- Physical Therapy, 7938University of Toronto, Toronto, Ontario, Canada
| | - Antenor Rodrigues
- Physical Therapy, 7938University of Toronto, Toronto, Ontario, Canada
| | - Shirin Tajali
- Physical Therapy, 7938University of Toronto, Toronto, Ontario, Canada
| | - Yijun Xiong
- Physical Therapy, 7938University of Toronto, Toronto, Ontario, Canada
| | - Ani Orchanian-Cheff
- Library and Information Services, 7989University Health Network, Toronto, Ontario, Canada
| | - W Darlene Reid
- Physical Therapy, 7938University of Toronto, Toronto, Ontario, Canada.,Interdepartmental Division of Critical Care Medicine, 7938University of Toronto, Toronto, Ontario, Canada.,KITE - Toronto Rehab-University Health Network, Toronto, Ontario, Canada
| | - Dmitry Rozenberg
- Department of Medicine, Division of Respirology, 7938University of Toronto, University Health Network, Toronto, Ontario, Canada.,Toronto General Hospital Research Institute, Toronto, Ontario, Canada
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Chuang ML, Hsieh BYT, Lin IF. Resting Dead Space Fraction as Related to Clinical Characteristics, Lung Function, and Gas Exchange in Male Patients with Chronic Obstructive Pulmonary Disease. Int J Gen Med 2021; 14:169-177. [PMID: 33568934 PMCID: PMC7868954 DOI: 10.2147/ijgm.s291555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 12/30/2020] [Indexed: 12/16/2022] Open
Abstract
Background Measures of forced expired volume in one second % predicted (FEV1%), residual volume to total lung capacity ratio (RV/TLC) and diffusing capacity for carbon monoxide measurements (DLCO) are the standard lung function test for evaluating patients with chronic obstructive pulmonary disease (COPD). The dead space fraction (VD/VT) has been shown to be a robust marker of gas exchange abnormality. However, the use of VD/VT has gradually become less common. As VD/VT measured at rest (VD/VTR) has been successfully used in non-COPD conditions, it was hypothesized that in COPD the VD/VTR was more sensitive than the standard lung function test in correlation with clinical characteristics and gas exchange. This study aimed to test the hypothesis and to identify the variables relevant to VD/VTR. Methods A total of 46 male subjects with COPD were enrolled. Clinical characteristics included demographic data, oxygen-cost diagram (OCD), and image studies for pulmonary hypertension. The standard lung function was obtained. To calculate VD/VT, invasive arterial blood gas and pulmonary gas exchange (PGX) were measured. The variables relevant to VD/VTR were analyzed by multiple linear regression. Results Compared to lung function, VD/VTR was more frequently and significantly related to smoking, carboxyhemoglobin level, pulmonary hypertension and PaCO2 (all p <0.05) whereas FEV1% was more related to lung function test, PaO2 and OCD score. VD/VTR and FEV1% were highly related to resting gas exchange but RV/TLC and DLCO% were not. Cigarette consumption, the equivalent for CO2 output, arterial oxyhemoglobin saturation, and the product of tidal volume and inspiratory duty cycle were identified as the parameters relevant to VD/VTR with a power of 0.72. Conclusion Compared to lung function test, VD/VTR is more related to clinical characteristics and is a comprehensive marker of resting gas exchange. Further studies are warranted to provide a noninvasive measurement of VD/VTR. Registration Number MOST 106-2314-B-040-025 and CSH-2019-C-30.
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Affiliation(s)
- Ming-Lung Chuang
- Division of Pulmonary Medicine and Department of Internal Medicine, Chung Shan Medical University Hospital, Taichung, Taiwan, 40201, Republic of China.,School of Medicine, Chung Shan Medical University, Taichung, Taiwan, 40201, Republic of China
| | | | - I-Feng Lin
- Institute of Public Health, National Yang Ming University, Taipei, Taiwan, 11221, Republic of China
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Changes in Respiratory Muscle Strength Following Cardiac Rehabilitation for Prognosis in Patients with Heart Failure. J Clin Med 2020; 9:jcm9040952. [PMID: 32235491 PMCID: PMC7230659 DOI: 10.3390/jcm9040952] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 03/25/2020] [Accepted: 03/27/2020] [Indexed: 12/28/2022] Open
Abstract
Respiratory muscle weakness, frequently observed in patients with heart failure (HF), is reported as a predictor for poor prognosis. Although increased respiratory muscle strength ameliorates exercise tolerance and quality of life in HF patients, the relationship between changes in respiratory muscle strength and patient prognosis remains unclear. A total of 456 patients with HF who continued a 5-month cardiac rehabilitation (CR) were studied. We measured maximal inspiratory pressure (PImax) at hospital discharge as the baseline and five months thereafter to assess the respiratory muscle strength. Changes in PImax during the 5-month observation period (⊿PImax) were examined. We investigated the composite multiple incidence of all-cause death or unplanned readmission after 5-month CR. The relationship between ⊿PImax and the incidence of clinical events was analyzed. Over a median follow-up of 1.8 years, 221 deaths or readmissions occurred, and their rate of incidence was 4.3/100 person-years. The higher ⊿PImax was significantly associated with lower incidence of clinical event. In multivariate Poisson regression model after adjustment for clinical confounding factors, ⊿PImax remained a significant and independent predictor for all-cause death/readmission (adjusted incident rate ratio for ⊿PImax increase of 10 cmH2O: 0.77, 95% confidence interval: 0.70–0.86). In conclusion, the changes in respiratory muscle strength independently predict the incidence of clinical events in patients with HF.
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