scholarly journals A Pilot Study on the Association of Mitochondrial Oxygen Metabolism and Gas Exchange During Cardiopulmonary Exercise Testing: Is There a Mitochondrial Threshold?

2020 ◽  
Vol 7 ◽  
Author(s):  
Philipp Baumbach ◽  
Christiane Schmidt-Winter ◽  
Jan Hoefer ◽  
Steffen Derlien ◽  
Norman Best ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Cardiopulmonary Exercise Testing ◽  
Oxygen Metabolism ◽  
Capillary Blood ◽  
Blood Gas ◽  
Cardiopulmonary Exercise ◽  
Blood Gas Analyses ◽  
End Tidal

Background: Mitochondria are the key players in aerobic energy generation via oxidative phosphorylation. Consequently, mitochondrial function has implications on physical performance in health and disease ranging from high performance sports to critical illness. The protoporphyrin IX-triplet state lifetime technique (PpIX-TSLT) allows in vivo measurements of mitochondrial oxygen tension (mitoPO2). Hitherto, few data exist on the relation of mitochondrial oxygen metabolism and ergospirometry-derived variables during physical performance. This study investigates the association of mitochondrial oxygen metabolism with gas exchange and blood gas analysis variables assessed during cardiopulmonary exercise testing (CPET) in aerobic and anaerobic metabolic phases.Methods: Seventeen volunteers underwent an exhaustive CPET (graded multistage protocol, 50 W/5 min increase), of which 14 were included in the analysis. At baseline and for every load level PpIX-TSLT-derived mitoPO2 measurements were performed every 10 s with 1 intermediate dynamic measurement to obtain mitochondrial oxygen consumption and delivery (mitoV.O2, mitoD.O2). In addition, variables of gas exchange and capillary blood gas analyses were obtained to determine ventilatory and lactate thresholds (VT, LT). Metabolic phases were defined in relation to VT1 and VT2 (aerobic: <VT1, aerobic-anaerobic transition: ≥VT1 and <VT2 and anaerobic: ≥VT2). We used linear mixed models to compare variables of PpIX-TSLT between metabolic phases and to analyze their associations with variables of gas exchange and capillary blood gas analyses.Results: MitoPO2 increased from the aerobic to the aerobic-anaerobic phase followed by a subsequent decline. A mitoPO2 peak, termed mitochondrial threshold (MT), was observed in most subjects close to LT2. MitoD.O2 increased during CPET, while no changes in mitoV.O2 were observed. MitoPO2 was negatively associated with partial pressure of end-tidal oxygen and capillary partial pressure of oxygen and positively associated with partial pressure of end-tidal carbon dioxide and capillary partial pressure of carbon dioxide. MitoD.O2 was associated with cardiovascular variables. We found no consistent association for mitoV.O2.Conclusion: Our results indicate an association between pulmonary respiration and cutaneous mitoPO2 during physical exercise. The observed mitochondrial threshold, coinciding with the metabolic transition from an aerobic to an anaerobic state, might be of importance in critical care as well as in sports medicine.

scholarly journals Correlation Between N-Terminal Pro-Brain Natriuretic Peptide Levels and Cardiopulmonary Exercise Testing in Patients With Pre-Capillary Pulmonary Hypertension: A Pilot Study

2020 ◽  
Vol 14 ◽  
pp. 117954842095404
Author(s):  
Sahachat Aueyingsak ◽  
Wilaiwan Khrisanapant ◽  
Upa Kukongviriyapun ◽  
Orapin Pasurivong ◽  
Pailin Ratanawatkul ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Pulmonary Hypertension ◽  
Brain Natriuretic Peptide ◽  
Natriuretic Peptide ◽  
Exercise Testing ◽  
Cardiopulmonary Exercise Testing ◽  
Chronic Thromboembolic Pulmonary Hypertension ◽  
Peak Oxygen Uptake ◽  
Cardiopulmonary Exercise ◽  
End Tidal

Background: N-terminal pro-brain natriuretic peptide (NT-proBNP) and cardiopulmonary exercise testing (CPET) are useful for severity assessment in patients with pulmonary hypertension (PH). Correlations between these tests in pre-capillary PH patients is less well studied. Methods: We studied 23 patients with pre-capillary PH: 8 with idiopathic pulmonary arterial hypertension (IPAH), 6 with systemic sclerosis-associated PAH (SSc-PAH), and 9 with chronic thromboembolic pulmonary hypertension (CTEPH). Clinical evaluation, NT-proBNP levels, six-minute walking test (6MWT), spirometry, and CPET were evaluated on the same day. Correlation between NT-proBNP levels and CPET parameters were investigated. Results: In all patients, NT-proBNP levels were significantly correlated with peak oxygen uptake (VO2) ( r = −0.47), peak oxygen pulse ( r = −0.43), peak cardiac output (CO) ( r = −0.57), peak end-tidal partial pressure of carbon dioxide (PETCO2) ( r = −0.74), ventilatory equivalent to carbon dioxide (VE/VCO2) at anaerobic threshold (AT) ( r = 0.73), and VE/VCO2 slope ( r = 0.64). Significant correlations between NT-proBNP levels and peak PETCO2 and VE/VCO2 were found in IPAH and CTEPH subgroups, and a significant correlation between NT-proBNP levels and VO2 at AT was found in the CTEPH subgroup. No significant correlation was found in the SSc-PAH subgroup. Conclusion: NT-proBNP levels were significantly correlated with CPET parameters in patients with IPAH and CTEPH subgroups, but not in SSc-PAH subgroup. A further study with larger population is required to confirm these preliminary findings.

Gas Exchange

2017 ◽  
Author(s):  
John W. Kreit
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Capillary Blood ◽  
Pressure Gradients ◽  
Arterial Blood ◽  
Pulmonary Capillary ◽  
Partial Pressures ◽  
Pulmonary Capillary Blood ◽  
And Diffusion

Gas Exchange explains how four processes—delivery of oxygen, excretion of carbon dioxide, matching of ventilation and perfusion, and diffusion—allow the respiratory system to maintain normal partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) in the arterial blood. Partial pressure is important because O2 and CO2 molecules diffuse between alveolar gas and pulmonary capillary blood and between systemic capillary blood and the tissues along their partial pressure gradients, and diffusion continues until the partial pressures are equal. Ventilation is an essential part of gas exchange because it delivers O2, eliminates CO2, and determines ventilation–perfusion ratios. This chapter also explains how and why abnormalities in each of these processes may reduce PaO2, increase PaCO2, or both.

scholarly journals EXPRESS: PeakPETCO2 combined with FEV1/FVC predicts vasodilator-responsive patients with idiopathic pulmonary arterial hypertension

2021 ◽  
pp. 204589402110597
Author(s):  
cijun Luo ◽  
Hong-Ling Qiu ◽  
Chang-wei Wu ◽  
Jing He ◽  
Ping Yuan ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Pulmonary Function ◽  
Partial Pressure ◽  
Minute Ventilation ◽  
Cardiopulmonary Exercise Testing ◽  
Prediction Rule ◽  
Pulmonary Artery Hypertension ◽  
Heart Catheterization ◽  
Hemodynamic Effects ◽  
End Tidal

Background: Cardiopulmonary exercise testing (CPET) and pulmonary function test (PFT) are important methods for detecting human cardio-pulmonary function. Whether they could screen vasoresponsiveness in idiopathic pulmonary artery hypertension (IPAH) patients remains undefined. Methods: One hundred thirty-two IPAH patients with complete data were retrospectively enrolled. Patients were classified as vasodilator-responsive (VR) group and vasodilator-nonresponsive (VNR) group on the basis of the acute vasodilator test. PFT and CPET were assessed subsequently and all patients were confirmed by right heart catheterization. We analyzed CPET and PFT data and derived a prediction rule to screen vasodilator-responsive patients in IPAH. Results: Nineteen of VR-IPAH and 113 of VNR-IPAH patients were retrospectively enrolled. Compared with VNR-IPAH patients, VR-IPAH patients had less severe hemodynamic effects (lower RAP, m PAP, PAWP and PVR). And VR-IPAH patients had higher anaerobic threshold (AT), peak partial pressure of end-tidal carbon dioxide (PETCO2), oxygen uptake efficiency (OUEP) and FEV1/FVC (P all < 0.05), while lower peak partial pressure of end-tidal oxygen (PETO2) and minute ventilation (VE)/carbon dioxide output (VCO2) slope (P all < 0.05). FEV1/FVC (Odds Ratio [OR]: 1.14, 95% confidence interval [CI]: 1.02-1.26, P = 0.02) and PeakPETCO2 (OR: 1.13, 95% CI: 1.01-1.26, P = 0.04) were independent predictors of VR adjusted for age, sex and body mass index. A novel formula (= -16.17 + 0.123 × PeakPETCO2 + 0.127×FEV1/FVC) reached a high area under the curve value of 0.8 (P = 0.003). Combined with these parameters, the optimal cutoff value of this model for detection of VR is -1.06, with a specificity of 91% and sensitivity of 67%. Conclusions: Compared with VNR-IPAH patients, VR-IPAH patients had less severe hemodynamic effects. Higher FEV1/FVC and higher peak PETCO2 were associated with increased odds for vasoresponsiveness. A novel score combining Peak PETCO2 and FEV1/FVC provides high specificity to predict VR patients among IPAH.

scholarly journals Cardiopulmonary exercise testing and echocardiographic exam: an useful interaction

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Ciro Santoro ◽  
Regina Sorrentino ◽  
Roberta Esposito ◽  
Maria Lembo ◽  
Valentina Capone ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ventilatory Threshold ◽  
Cardiopulmonary Exercise Testing ◽  
Cardiopulmonary Exercise Test ◽  
Exercise Stress ◽  
Oxygen Intake ◽  
Reduced Ejection Fraction ◽  
Cardiopulmonary Exercise ◽  
Artery Disease ◽  
End Tidal

AbstractCardiopulmonary exercise test (CPET) is a functional assessment that helps to detect disorders affecting the system involved in oxygen transport and utilization through the analysis of the gas exchange during exercise. The clinical application of CPET is various, it including training prescription, evaluation of treatment efficacy and outcome prediction in a broad spectrum of conditions. Furthermore, in patients with shortness of breath it provides pivotal information to bring out an accurate differential diagnosis between physical deconditioning, cardiopulmonary disease and muscular diseases. Modern software allows the breath-by-breath analysis of the volume of oxygen intake (VO2), volume of carbon dioxide output (VCO2) and expired air (VE). Through this analysis, CPET provides a series of additional parameters (peak VO2, ventilatory threshold, VE/VCO2 slope, end-tidal carbon dioxide exhaled) that characterize different patterns, helping in diagnosis process. Limitations to the routine use of CPET are mainly represented from the lack of measurement standardization and limited data from randomized multicentric studies. The integration of CPET with exercise stress echocardiography has been recently introduced in the clinical practice by integrating the diagnostic power offered by both the tools. This combined approach has been demonstrated to be valuable for diagnosing several cardiac diseases, including heart failure with preserved or reduced ejection fraction, cardiomyopathies, pulmonary arterial hypertension, valvular heart disease and coronary artery disease. Future investigations are needed to further promote this intriguing combination in the clinical and research setting.

Blood-gas equilibrium of carbon dioxide in lungs: a continuing controversy

1986 ◽  
Vol 60 (1) ◽  
pp. 1-8 ◽  
Author(s):  
J. Piiper
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Steady State ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Experimental Error ◽  
Blood Gas ◽  
Co2 Partial Pressure ◽  
Future Work ◽  
Alveolar Gas Exchange

This review presents the experimental evidence that has been published in recent years both against and in support of the occurrence of negative blood-gas CO2 partial pressure differences (delta PCO2) in lungs in rebreathing equilibrium and during steady-state gas exchange in hypercapnia. Although some sources of potential experimental error can be pointed out, the reasons for the remarkably pronounced disagreement between the experimental data of the different studies cannot be definitely identified. Since a consistent and reproducible occurrence of negative blood-gas delta PCO2 in lungs in gas-blood equilibrium is not convincingly proved, it appears to be justified to continue accepting the validity of the conventional concept of equal PCO2 in blood and gas in equilibrium. Because the issue is of considerable importance in the analysis and understanding of alveolar gas exchange, pertinent evidence is expected from future work.

scholarly journals Ventilatory response to exercise in cardiopulmonary disease: the role of chemosensitivity and dead space

2018 ◽  
Vol 51 (2) ◽  
pp. 1700860 ◽  
Author(s):  
Jason Weatherald ◽  
Caroline Sattler ◽  
Gilles Garcia ◽  
Pierantonio Laveneziana
Keyword(s):  
Gas Exchange ◽  
Partial Pressure ◽  
Dead Space ◽  
Ventilatory Response ◽  
Heart Function ◽  
Cardiopulmonary Exercise Testing ◽  
Cardiopulmonary Disease ◽  
The Difference ◽  
End Tidal ◽  
Response To Exercise

The lungs and heart are irrevocably linked in their oxygen (O2) and carbon dioxide (CO2) transport functions. Functional impairment of the lungs often affects heart function andvice versa. The steepness with which ventilation (V′E) rises with respect to CO2production (V′CO2) (i.e.theV′E/V′CO2slope) is a measure of ventilatory efficiency and can be used to identify an abnormal ventilatory response to exercise. TheV′E/V′CO2slope is a prognostic marker in several chronic cardiopulmonary diseases independent of other exercise-related variables such as peak O2uptake (V′O2). TheV′E/V′CO2slope is determined by two factors: 1) the arterial CO2partial pressure (PaCO2) during exercise and 2) the fraction of the tidal volume (VT) that goes to dead space (VD) (i.e.the physiological dead space ratio (VD/VT)). An alteredPaCO2set-point and chemosensitivity are present in many cardiopulmonary diseases, which influenceV′E/V′CO2by affectingPaCO2. Increased ventilation–perfusion heterogeneity, causing inefficient gas exchange, also contributes to the abnormalV′E/V′CO2observed in cardiopulmonary diseases by increasingVD/VT. During cardiopulmonary exercise testing, thePaCO2during exercise is often not measured andVD/VTis only estimated by taking into account the end-tidal CO2partial pressure (PETCO2); however,PaCO2is not accurately estimated fromPETCO2in patients with cardiopulmonary disease. Measuring arterial gases (PaO2andPaCO2) before and during exercise provides information on the real (and not “estimated”)VD/VTcoupled with a true measure of gas exchange efficiency such as the difference between alveolar and arterial O2partial pressure and the difference between arterial and end-tidal CO2partial pressure during exercise.

scholarly journals Ventilatory compensation during the incremental exercise test is inversely correlated with air trapping in COPD

F1000Research ◽  
2020 ◽  
Vol 8 ◽  
pp. 1661
Author(s):  
Rottem Kuint ◽  
Neville Berkman ◽  
Samir Nusair
Keyword(s):  
Gas Exchange ◽  
Exercise Testing ◽  
Exercise Test ◽  
Cardiopulmonary Exercise Testing ◽  
Incremental Exercise ◽  
Peak Exercise ◽  
Air Trapping ◽  
Incremental Exercise Test ◽  
Cardiopulmonary Exercise ◽  
Copd Patients

Background: Air trapping and gas exchange abnormalities are major causes of exercise limitation in chronic obstructive pulmonary disease (COPD). During incremental cardiopulmonary exercise testing, actual nadir values of ventilatory equivalents for carbon dioxide (V E/VCO 2) and oxygen (V E/VO 2) may be difficult to identify in COPD patients because of limited ventilatory compensation capacity. Therefore, we aimed in this exploratory study to detect a possible correlation between the magnitude of ventilation augmentation, as manifested by increments in ventilatory equivalents from nadir to peak exercise values and air trapping, detected with static testing.    Methods: In this observational study, we studied data obtained previously from 20 COPD patients who, during routine follow-up, underwent a symptom-limited incremental exercise test and in whom a plethysmography was obtained concurrently. Air trapping at rest was assessed by measurement of the residual volume (RV) to total lung capacity (TLC) ratio (RV/TLC). Gas exchange data collected during the symptom-limited incremental cardiopulmonary exercise test allowed determination of the nadir and peak exercise values of V E/VCO 2 and V E/VO 2, thus enabling calculation of the difference between peak exrcise value and nadir values of  V E/VCO 2 and V E/VO 2, designated ΔV E/VCO 2 and ΔV E/VO 2, respectively. Results: We found a statistically significant inverse correlation between both ΔV E/VCO 2 (r = -0. 5058, 95% CI -0.7750 to -0.08149, p = 0.0234) and ΔV E/VO 2 (r = -0.5588, 95% CI -0.8029 to -0.1545, p = 0.0104) and the degree of air trapping (RV/TLC). There was no correlation between ΔV E/VCO 2 and forced expiratory volume in the first second, or body mass index.  Conclusions: The ventilatory equivalents increment to compensate for acidosis during incremental exercise testing was inversely correlated with air trapping (RV/TLC).

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