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Chinnappa S, White E, Lewis N, Baldo O, Tu YK, Glorieux G, Vanholder R, El Nahas M, Mooney A. Early and asymptomatic cardiac dysfunction in chronic kidney disease. Nephrol Dial Transplant 2019; 33:450-458. [PMID: 28525624 DOI: 10.1093/ndt/gfx064] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 03/14/2017] [Indexed: 11/13/2022] Open
Abstract
Background Heart failure (HF) is highly prevalent and associated with high mortality in chronic kidney disease (CKD). However, the pathophysiology of cardiac dysfunction in CKD, especially in the early asymptomatic stage, is not well understood. We studied subclinical cardiac dysfunction in asymptomatic CKD patients without comorbid cardiac disease or diabetes mellitus by evaluating peak cardiac performance. Methods In a cross-sectional study (n = 130) we investigated 70 male non-diabetic CKD patients (21 CKD stage 2-3a, 27 CKD stage 3b-4 and 22 CKD stage 5) employing specialized cardiopulmonary exercise testing to measure peak cardiac output and cardiac power output non-invasively. Data from 35 age-matched healthy male volunteers were obtained for comparison. In addition, as a positive control, data from 25 age-matched male HF patients in New York Heart Association class II and III were also obtained. Results The study subjects showed a graded reduction in peak cardiac power, with 6.13 ± 1.11 W in controls, 5.02 ± 0.78 W in CKD 2-3a, 4.59 ± 0.53 W in CKD 3b-4 and 4.02 ± 0.73 W in CKD 5, although not as impaired as in HF, with 2.34 ± 0.63 W (all P < 0.005 versus control). The central haemodynamic characteristics of the cardiac impairment in CKD mirrored that of HF, with reduced flow and pressure-generating capacities, reduced chronotropic reserve and impaired contractility. Conclusions The study demonstrates for the first time impaired peak cardiac performance and cardiac functional reserve in asymptomatic CKD patients. The evidence of myocardial dysfunction in the absence of comorbid cardiac disease and diabetes warrants further evaluation of current pathophysiological concepts of cardiovascular disease in CKD.
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Affiliation(s)
- Shanmugakumar Chinnappa
- Department of Nephrology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK.,Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Edward White
- School of Biomedical Sciences, University of Leeds, Leeds, UK
| | - Nigel Lewis
- Department of Cardiology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Omer Baldo
- Department of Urology, Airedale NHS Foundation Trust, Keighley, UK
| | - Yu-Kang Tu
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National University of Taiwan, Taiwan
| | - Griet Glorieux
- Department of Nephrology, Ghent University Hospital, Ghent, Belgium
| | | | - Meguid El Nahas
- Department of Nephrology, University of Sheffield, Sheffield, UK
| | - Andrew Mooney
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK.,Department of Nephrology, Leeds Teaching Hospitals NHS Trust, Leeds, UK
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Braz GP, Russold MF, Fornusek C, Hamzaid NA, Smith RM, Davis GM. Cardiorespiratory and Muscle Metabolic Responses During Conventional Versus Motion Sensor-Assisted Strategies for Functional Electrical Stimulation Standing After Spinal Cord Injury. Artif Organs 2016; 39:855-62. [PMID: 26471136 DOI: 10.1111/aor.12619] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This is a case series study with the objective of comparing two motion sensor automated strategies to avert knee buckle during functional electrical stimulation (FES)-standing against a conventional hand-controlled (HC) FES approach. The research was conducted in a clinical exercise laboratory gymnasium at the University of Sydney, Australia. The automated strategies, Aut-A and Aut-B, applied fixed and variable changes of neurostimulation, respectively, in quadriceps amplitude to precisely control knee extension during standing. HC was an "on-demand" increase of stimulation amplitude to maintain stance. Finally, maximal FES amplitude (MA) was used as a control condition, whereby knee buckle was prevented by maximal isometric muscle recruitment. Four AIS-A paraplegics undertook 4 days of testing each, and each assessment day comprised three FES standing trials using the same strategy. Cardiorespiratory responses were recorded, and quadriceps muscle oxygenation was quantified using near-infrared spectroscopy. For all subjects, the longest standing times were observed during Aut-A, followed by Aut-B, and then HC and MA. The standing times of the automated strategies were superior to HC by 9-64%. Apart from a lower heart rates during standing (P = 0.034), the automation of knee extension did not promote different cardiorespiratory responses compared with HC. The standing times during MA were significantly shorter than during the automated or "on-demand" strategies (by 80-250%). In fact, the higher isometric-evoked quadriceps contraction during MA resulted in a greater oxygen demand (P < 0.0001) and wider arteriovenous oxygen extraction (P = 0.08) when compared with the other strategies. In conclusion, even though increased standing times were demonstrated using automated control of knee extension, physiological benefits compared with HC were not evident.
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Affiliation(s)
- Gustavo P Braz
- Clinical Exercise and Rehabilitation Unit, The University of Sydney, Sydney, NSW, Australia.,Discipline of Exercise and Sports Science, The University of Sydney, Sydney, NSW, Australia
| | - Michael F Russold
- Clinical Exercise and Rehabilitation Unit, The University of Sydney, Sydney, NSW, Australia
| | - Ché Fornusek
- Clinical Exercise and Rehabilitation Unit, The University of Sydney, Sydney, NSW, Australia.,Discipline of Exercise and Sports Science, The University of Sydney, Sydney, NSW, Australia
| | - Nur Azah Hamzaid
- Clinical Exercise and Rehabilitation Unit, The University of Sydney, Sydney, NSW, Australia.,Biomedical Engineering Department, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
| | - Richard M Smith
- Discipline of Exercise and Sports Science, The University of Sydney, Sydney, NSW, Australia
| | - Glen M Davis
- Clinical Exercise and Rehabilitation Unit, The University of Sydney, Sydney, NSW, Australia.,Discipline of Exercise and Sports Science, The University of Sydney, Sydney, NSW, Australia.,Biomedical Engineering Department, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia
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3
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Wenner MM, Edwards DG, Ray CA, Rose WC, Gardner TJ, Stillabower M, Farquhar WB. Celecoxib does not alter cardiovascular and renal function during dietary salt loading. Clin Exp Pharmacol Physiol 2012; 38:543-9. [PMID: 21631568 DOI: 10.1111/j.1440-1681.2011.05546.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. Cyclo-oxygenase-2 (COX-2)-derived prostaglandins are important in controlling sodium excretion and renin release. In the present study, we tested the hypothesis that a clinical dose of celecoxib would impair urinary sodium excretion and elevate blood pressure (BP) during dietary salt loading. 2. Twelve normotensive individuals (mean (± SEM) age 35 ± 2 years) completed two separate 17 day dietary perturbations, one taking 200 mg/day celecoxib (CX2) and the other taking placebo (PL), randomized with a 1 month wash out. The controlled 17 day diet consisted of a 3 day run-in diet, 7 days of a low-salt (LS, 20 mmol sodium/day) diet and 7 days of a high-salt diet (HS, 350 mmol sodium/day) diet. The order in which the diets were applied was randomized. Data were collected on the last day of the LS and HS diets. 3. Plasma and urinary prostaglandins were modestly lower during celecoxib (P < 0.05). Urinary sodium excretion was greater (P < 0.01) during the HS diet (253 ± 10 vs 281 ± 27 mmol/24 h for PL vs CX2, respectively) compared with the LS diet (14 ± 3 vs 17 ± 7 mmol/24 h for PL vs CX2, respectively; P(drug) = 0.26). Celecoxib did not alter creatinine clearance (P > 0.50). Twenty-four hour mean arterial BP was similar during PL (87 ± 2 vs 87 ± 2 mmHg for LS and HS, respectively) and CX2 (88 ± 2 vs 87 ± 2 mmHg for LS and HS, respectively; P = 0.85), with no effect of dietary salt (P > 0.80). Plasma renin activity, angiotensin II and aldosterone were all suppressed with dietary salt loading (P < 0.05), with no effect of drug (P > 0.35). 4. In conclusion, blood pressure and renal function were not adversely affected by celecoxib, even during dietary salt loading. These findings support current guidelines suggesting minimal cardiovascular risks associated with short-term, low-dose use of celecoxib in young to middle-aged adults.
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Affiliation(s)
- Megan M Wenner
- Department of Kinesiology and Applied Physiology, University of Delaware, USA
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4
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Abstract
Hemodynamic monitoring in critically ill patients has been considered part of the standard of care in managing patients with shock and/or acute lung injury, but outcome benefit, particularly in pediatric patients, has been questioned. There is difficulty in validating the reliability of monitoring devices, especially since this validation requires comparison to the pulmonary artery catheter, which has its own problems as a measurement tool. Interpretation of the available evidence reveals advantages and disadvantages of the available hemodynamic monitoring devices.
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5
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Trilk JL, Singhal A, Bigelman KA, Cureton KJ. Effect of sprint interval training on circulatory function during exercise in sedentary, overweight/obese women. Eur J Appl Physiol 2010; 111:1591-7. [DOI: 10.1007/s00421-010-1777-z] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2010] [Indexed: 11/29/2022]
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6
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Noninvasive monitoring cardiac output using partial CO(2) rebreathing. Crit Care Clin 2010; 26:383-92, table of contents. [PMID: 20381727 DOI: 10.1016/j.ccc.2009.12.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This article reviews use of partial carbon dioxide rebreathing devices to determine cardiac output and their application for hemodynamic monitoring in the ICU and operating room. The primary focus is on the NICO monitoring device. Compared with conventional cardiac output methods, these techniques are noninvasive, easily automated, and provide real-time and continuous cardiac output monitoring. The advantages and limitations of each technique are different discussed.
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Pittrow D, Schindler C, Maywald U, Tölge D, Kirch W. Cardiovascular Parameters during Submaximal Exercise following Submucous Administration of Articaine : A Comparison with Lidocaine and Placebo in Young Healthy Volunteers. Clin Drug Investig 2007; 23:219-23. [PMID: 17535034 DOI: 10.2165/00044011-200323040-00001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
OBJECTIVE Local anaesthetics have been shown to exert pronounced cardiodepressant effects after intravenous administration in high doses. Thus, we compared the cardiovascular effects of articaine with those of lidocaine and placebo after submucous administration in healthy volunteers during bicycle exercise ergometry. PARTICIPANTS AND METHODS A single-blind, randomised, placebo-controlled, crossover study design with washout periods of 1 week each between the three treatment days was used. Articaine 40mg (A), lidocaine 40mg (L) and placebo (P) were injected submucously in the upper jaw in 12 healthy male volunteers who had had cardiovascular diseases excluded. Parameters measured at baseline and at 15 minutes, 60 minutes and 105 minutes were systolic blood pressure (BP) and heart rate at 50W, 100W and 150W, and cardiac output at 100W. Tolerability was assessed by ECG measurements and through reporting of adverse events. RESULTS 15 minutes after drug administration, cardiac output was reduced by -3.8% (P), -6.8% (A), and -4.2% (L) [difference between groups was not significant]. There were also no statistically significant differences between groups for cardiac output at 60 and 105 minutes, or for all BP and heart rate measurements. CONCLUSIONS Neither drug exhibited significant effects on selected cardiovascular parameters during submaximal exercise when compared with placebo.
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Affiliation(s)
- D Pittrow
- Institute of Clinical Pharmacology, Medical Faculty, Technical University of Dresden, Dresden, Germany
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8
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Yem JS, Turner MJ, Baker AB. Sources of error in partial rebreathing pulmonary blood flow measurements in lungs with emphysema and pulmonary embolism. Br J Anaesth 2006; 97:732-41. [PMID: 16926170 DOI: 10.1093/bja/ael214] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Studies of the accuracy of partial rebreathing measurements of pulmonary blood flow (PBF) in patients with abnormal lungs have not fully explained the sources of error. METHODS We used computer models of emphysema and pulmonary embolism incorporating both ventilation-perfusion (V/Q) and ventilation-volume (V/V) heterogeneity to investigate systematic errors in partial rebreathing PBF measurements. We studied (i) errors produced under usual conditions, (ii) effects of recirculation, (iii) effects of alveolar-proximal airway and alveolar-capillary PCO2 and VCO2 differences, (iv) effects of alveolar V/Q inhomogeneity and (v) effects of rebreathing time. RESULTS In the pulmonary embolism model the systematic error is only acceptable (<10%) when the simulated PBF is low (2-3 litre min(-1)). In the emphysema model PBF is underestimated by more than 20% at all cardiac outputs studied. Four sources of systematic errors were found. (i) Alveolar-proximal airway PCO2 gradients and flux differences between the proximal airway and alveolar compartments contribute most to the systematic error. (ii) V/Q inhomogeneity causes PCO2 gradients between the alveolar compartments and pulmonary capillary blood, and between pulmonary capillary compartments. (iii) Rebreathing times are inadequate in the presence of V/V mismatch. (iv) The apparent effect of venous blood recirculation is small in emphysema but significant in pulmonary embolism. CONCLUSIONS We conclude that PBF cannot be measured accurately by partial rebreathing in lungs with emphysema or embolism. Systematic errors are caused mainly by errors in end-tidal PCO2 values.
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Affiliation(s)
- J S Yem
- Department of Anaesthetics, The University of Sydney, Royal Prince Alfred Hospital Missenden Road, Camperdown, NSW 2050, Australia
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9
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Benallal H, Denis C, Prieur F, Busso T. Assessment of arterial gas pressures and cardiac output using a breathing lung model. Med Sci Sports Exerc 2002; 34:1750-6. [PMID: 12439079 DOI: 10.1097/00005768-200211000-00010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE The aim of this investigation was to evaluate a breathing lung model to estimate arterial gas partial pressures and cardiac output at rest and during exercise. METHODS A mathematical model was used to describe variations in gas fractions, alveolar volume, and gas exchange in the pulmonary capillaries during the breathing cycle. Experimental data were obtained from 17 healthy subjects at rest and during exercise at 40, 50, 65, and 75% VO(2max) on a cycle ergometer. VO(2), VCO(2), and P(ET,CO2) were monitored continuously with a MedGraphics CPX/D gas exchange system. Arterial gases were measured in brachial artery blood samples drawn simultaneously with gas exchange. Cardiac output was measured using the CO(2) rebreathing method corrected by the arterial blood sample data. The model parameters including cardiac output, end-expiratory alveolar volume, and mixed-venous gas contents were estimated by fitting modelVCO(2) to experimental values over 50 breaths. RESULTS The fit of model parameters gave arterial gas partial pressures not significantly different from measured data. Measured P(a,C02) and P(a,O2) were significantly correlated with model outputs (R(2) = 0.991 for P(a,CO2) and R(2) = 0.999 for P(a, CO2); P < 0.0001). The cardiac output values estimated using the breathing lung model were significantly correlated with the values obtained with the corrected CO rebreathing method (R(2) = 0.71; P < 0.0001). There was, however, a significant 2.3 L x min(-1) difference between these two methods. CONCLUSION Results obtained with the proposed method were in good agreement with measured arterial gas partial pressures. Despite a certain degree of bias, the promising results for cardiac output demonstrate the reliability of this method that should be now evaluated using a gold standard method.
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Affiliation(s)
- Habib Benallal
- Laboratoire de Physiologie et Physiopathologie de L'Exercice et Handicap--Groupement d'Intérêt Public Exercice, Sport et Santé, Université Jean Monnet, Saint-Etienne, France.
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10
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Vanhees L, Defoor J, Schepers D, Brusselle S, Reybrouck T, Fagard R. Comparison of cardiac output measured by two automated methods of CO2 rebreathing. Med Sci Sports Exerc 2000; 32:1028-34. [PMID: 10795797 DOI: 10.1097/00005768-200005000-00023] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE The aim of the present study was to investigate the reproducibility of the exponential method of CO2 rebreathing with the use of automated curve fitting and to determine whether this method is superior to the equilibrium method in terms of reproducibility and clinical practicability. METHODS Repeated measurements of cardiac output were performed using the automated equilibrium and exponential methods. These measurements were compared in 12 healthy male subjects at rest and during incremental exercise tests. RESULTS Estimated cardiac output was not significantly different between duplicate measurements at rest nor at any level of exercise with either method. At rest the exponential method showed a tendency toward larger variability than the equilibrium method. The exponential method produced significantly higher (P < or = 0.001) estimates at rest (averaging up to 9.8 L x min(-1)) compared with the equilibrium method (averaging up to 6.5 L x min(-1)). Reproducibility improved for both methods with increasing workloads, and a second measurement at rest also seemed more reproducible and valid than the first. During exercise, both methods produced comparable values for cardiac output, and highly significant relations between cardiac output and oxygen uptake were observed for both methods (ranging from r2 = 0.79 to r2 = 0.88, P < or = 0.001). The equilibrium method produced unpleasant side effects more frequently (75% vs 21%, P < or = 0.001) compared with the exponential method and lead more subjects to premature interruption of the exercise test because of the rebreathing maneuver (42% vs 17%, P = 0.058). CONCLUSIONS Automated curve fitting for the exponential method gave reproducible and valid results during submaximal and maximal exercise but not at rest. The equilibrium method on the other hand interfered with exercise. Therefore, the equilibrium method is recommended at rest and at lower levels of exercise and the exponential method at higher intensities.
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Affiliation(s)
- L Vanhees
- Department of Molecular and Cardiovascular Research, Faculty of Medicine, K. U. Leuven, Belgium.
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11
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Miller DM, Wessels JA. A simple method for the continuous noninvasive estimate of cardiac output using the Maxima breathing system. A pilot study. Anaesth Intensive Care 1997; 25:23-8. [PMID: 9075509 DOI: 10.1177/0310057x9702500104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The Maxima is a new breathing system which makes it possible to monitor cardiac output (Q) noninvasively and to follow trends continuously. When used as a rebreathing system in controlled ventilation, the Maxima selectively eliminates alveolar gas and no fresh gas (VF) is eliminated. Without the need for a mixing chamber, eliminated CO2 (FeCO2) may be measured directly. With steady state conditions, and assuming a respiratory quotient of 1, carbon dioxide production (VCO2) = VF x FeCO2. The indirect Fick principle applied to CO2 exchange (Q = VCO2/ venous-to-arterial CO2 content difference (CaCO2-CvCO2) may be modified to Q = VF x FeCO2/(CaCO2-CvCO2). If VF in the breathing system is adjusted so that FeCO2 is equal to CaCO2-CvCO2, then Q = VF. It was found that, in the presence of a normal haemoglobin (13.3 g.dl-1), Q = VF when VF was adjusted to achieve an FeCO2 value of approximately 4.1%. Cardiac output estimates were compared with those obtained using a thermodilution technique in five patients undergoing coronary artery bypass grafting and in four patients with septicaemia in the ICU. Cardiac outputs were estimated from 1. VCO2 measurements and then 2. VCO2 and haemoglobin (Hb). The result of 28 measurements on nine patients with methods 1. and 2. respectively yielded a correlation with thermodilution measurements: coefficient r = 0.91 and 0.94 with a bias of -10.5% and -0.05% and an accuracy of 14% and 9%.
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Affiliation(s)
- D M Miller
- Department of Anaesthesiology, University of Stellenbosch, Tygerberg Hospital, South Africa
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12
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Palange P, Forte S, Felli A, Galassetti P, Serra P, Carlone S. Nutritional state and exercise tolerance in patients with COPD. Chest 1995; 107:1206-12. [PMID: 7750307 DOI: 10.1378/chest.107.5.1206] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We hypothesized that in patients with COPD, poor nutritional status adversely influences exercise tolerance by limiting aerobic capacity of exercising muscles. In 28 patients with stable COPD, we correlated nutritional status with gas exchange indexes obtained during maximal incremental cycle ergometer exercise and with respiratory function parameters. On the basis of percent of ideal body weight (%IBW), patients were divided into three groups (GP): GP1 (n = 8, %IBW < 90); GP2 (n = 13, %IBW > or = 90 < 110); and GP3 (n = 7, %IBW > or = 110). When compared with normally nourished individuals (GPs 2 and 3), malnourished GP1 patients showed greater reduction in maximal workload and in peak O2 uptake (VO2 peak), with earlier onset of metabolic acidosis (anaerobic threshold [AT]); in addition, indexes reflecting O2 cost of ventilation were higher in GP1. Nutritional status could be correlated with exercise tolerance (VO2 peak, r = 0.82, p < 0.0001), with onset of metabolic acidosis (AT, r = 0.69, p < 0.0001) and with dead space/tidal volume ratio (VD/VT, r = -0.59, p < 0.001). Body weight was inversely correlated with indexes that are likely to reflect the increase in O2 cost of ventilation. We conclude that in patients with stable COPD, (1) malnutrition significantly affects muscle aerobic capacity and exercise tolerance, and (2) high wasted ventilation and O2 cost of ventilation may be responsible for the weight loss.
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Affiliation(s)
- P Palange
- II Patologia Medica, University of Rome La Sapienza Italy
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13
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Palange P, Carlone S, Forte S, Galassetti P, Serra P. Cardiopulmonary exercise testing in the evaluation of patients with ventilatory vs circulatory causes of reduced exercise tolerance. Chest 1994; 105:1122-6. [PMID: 8162736 DOI: 10.1378/chest.105.4.1122] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
INTRODUCTION Cardiopulmonary exercise testing (CPX) is considered a useful procedure in the evaluation of circulatory, ventilatory, or mixed origin of reduced exercise tolerance. Our study was designed to compare CPX and a standard clinical-instrumental approach in the evaluation of patients with cardiopulmonary disorders. METHODS Fifty-seven patients (31 male, 26 female; mean [+/- SE] age, 60 +/- 2 years) were studied. Each patient was evaluated by two different observers: one used standard clinical criteria, the other used gas exchange indexes, monitored during a maximal incremental CPX, performed on a cycle ergometer. Cardiac output (CO), at rest and at submaximal work level, was also obtained. RESULTS In 46 patients (80.7 percent), a concordant evaluation was reached by the two observers (24 were found to have a predominant ventilatory disorder, 22 to have a circulatory disorder); among these, in subjects considered to have circulatory impairment, the maximal CO/maximal workload ratio was significantly lower than in the ventilatory group; in those with ventilatory impairment, the reduced exercise tolerance correlated with the resting spirometric values. In the remaining 11 patients (19.3 percent), CPX better defined the underlying pathophysiology of exercise limitation: in 10 of them, clinically classified as having a mixed or predominantly ventilatory disorder, a greater importance of the circulatory component was detected; 4 had evidence of pulmonary vascular impairment (high VE/VCO2 at anaerobic threshold). CONCLUSIONS Our study confirmed the sensitivity of CPX in the evaluation of a reduced exercise tolerance in dyspneic patients with cardiopulmonary conditions; when compared with a clinical-laboratory approach, in some patients it allowed the detection of an underestimated circulatory component causing exercise limitation.
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Affiliation(s)
- P Palange
- II Patologia Medica, University La Sapienza Rome, Italy
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Hanna RD, Sheldahl LM, Tristani FE. Effect of enhanced preload with head-out water immersion on exercise response in men with healed myocardial infarction. Am J Cardiol 1993; 71:1041-4. [PMID: 8475866 DOI: 10.1016/0002-9149(93)90570-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Head-out water immersion shifts venous blood to the central vasculature and heart and subsequently increases cardiac preload. In healthy men, cardiac output and stroke volume are greater during upright leg cycle exercise in water than on land. Heart rate is similar during work loads < 50% of peak oxygen consumption but is decreased in water at higher work intensities. To determine if men with myocardial infarction (MI) show a similar response, 15 men with a documented MI exercised upright on a leg cycle ergometer on land and immersed in water (31 +/- 1 degree C) to the level of the shoulders. Heart rate, cardiac output (carbon dioxide rebreathing procedure) and oxygen consumption were measured at rest and at work loads corresponding to approximately 40, 60 and 75% of peak oxygen consumption in both environments. At rest, cardiac output and stroke volume were elevated (p < 0.05) in water. During exercise, heart rate, cardiac output and stroke volume did not differ between water and land. When subjects were given beta-blocking medications (n = 8) and subjects with exercise-induced ST-segment depression (n = 5) were separately excluded from the analysis, water immersion still did not significantly change exercise responses. These results suggest that MI alters the normal cardiac response to increased preload during exercise. The alteration may involve reduced myocardial compliance or near-complete use of the Frank-Starling reserve, or both, during land exercise.
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Affiliation(s)
- R D Hanna
- Department of Medicine and Physiology, Medical College of Wisconsin, Milwaukee
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15
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Andersen HB, Jensen EW, Madsbad S, Nielsen SL, Burcharth F, Christensen NJ. Sham-feeding decreases cardiac output in normal subjects. CLINICAL PHYSIOLOGY (OXFORD, ENGLAND) 1992; 12:439-42. [PMID: 1505165 DOI: 10.1111/j.1475-097x.1992.tb00347.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The cardiovascular effect of sham-feeding was measured in seven healthy non-obese human subjects by the Fick principle using the carbon dioxide rebreathing method. The subjects were resting in the sitting position and were exposed to the sight and smell but not the taste of a breakfast meal. Cardiac output decreased significantly from a mean value of 4.0 1 min-1 to 3.5 1 min-1 during sham-feeding (Friedman, P = 0.004). The cardiac output returned to basal values in all seven subjects when the sensory stimulus was removed. The decrease in cardiac output was due to a decreased stroke volume, whereas heart rate and blood pressure did not change. The mechanism of the decrease in cardiac output during sham-feeding remains to be established.
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Affiliation(s)
- H B Andersen
- Department of Internal Medicine and Endocrinology, Herlev Hospital, University of Copenhagen, Denmark
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