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1.
Med Sci Sports Exerc ; 49(10): 1993-2000, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28538026

RESUMO

INTRODUCTION: Burn trauma damages resting cardiac function; however, it is currently unknown if the cardiovascular response to exercise is likewise impaired. We tested the hypothesis that, in children, burn injury lowers cardiac output (Q˙) and stroke volume (SV) during submaximal exercise. METHODS: Five children with 49% ± 4% total body surface area (BSA) burned (two female, 11.7 ± 1 yr, 40.4 ± 18 kg, 141.1 ± 9 cm) and eight similar nonburned controls (five female, 12.5 ± 2 yr, 58.0 ± 17 kg, 147.3 ± 12 cm) with comparable exercise capacity (peak oxygen consumption [peak V˙O2]: 31.9 ± 11 vs 36.8 ± 8 mL O2·kg·min, P = 0.39) participated. The exercise protocol entailed a preexercise (pre-EX) rest period followed by 3-min exercise stages at 20 W and 50 W. V˙O2, HR, Q˙ (via nonrebreathing), SV (Q˙/HR), and arteriovenous O2 difference ([a-v]O2diff, Q˙/ V˙O2) were the primary outcome variables. RESULTS: Using a 2-way factorial ANOVA (group [G] × exercise [EX]), we found that Q˙ was approximately 27% lower in the burned than the nonburned group at 20 W of exercise (burned 5.7 ± 1.0 vs nonburned: 7.9 ± 1.8 L·min) and 50 W of exercise (burned 6.9 ± 1.6 vs nonburned 9.2 ± 3.2 L·min) (G-EX interaction, P = 0.012). SV did not change from rest to exercise in burned children but increased by approximately 24% in the nonburned group (main effect for EX, P = 0.046). Neither [a-v] O2diff nor V˙O2 differed between groups at rest or exercise, but HR response to exercise was reduced in the burn group (G-EX interaction, P = 0.004). When normalized to BSA, SV (index) was similar between groups; however, Q˙ (index) remained attenuated in the burned group (G-EX interaction, P < 0.008). CONCLUSIONS: Burned children have an attenuated cardiovascular response to submaximal exercise. Further investigation of hemodynamic function during exercise will provide insights important for cardiovascular rehabilitation in burned children.


Assuntos
Queimaduras/fisiopatologia , Débito Cardíaco/fisiologia , Exercício Físico/fisiologia , Adolescente , Superfície Corporal , Criança , Teste de Esforço , Feminino , Humanos , Masculino , Oxigênio/sangue , Consumo de Oxigênio/fisiologia , Volume Sistólico/fisiologia
2.
Physiol Rep ; 4(13)2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27418546

RESUMO

Heart failure (HF) is often associated with pulmonary congestion, reduced lung function, abnormal gas exchange, and dyspnea. We tested whether pulmonary congestion is associated with expanded vascular beds or an actual increase in extravascular lung water (EVLW) and how airway caliber is affected in stable HF Subsequently we assessed the influence of an inhaled short acting beta agonist (SABA). Thirty-one HF (7F; age, 62 ± 11 years; ht. 175 ± 9 cm; wt. 91 ± 17 kg; LVEF, 28 ± 15%) and 29 controls (11F; age; 56 ± 11 years; ht. 174 ± 8 cm; wt. 77 ± 14 kg) completed the study. Subjects performed PFTs and a chest computed tomography (CT) scan before and after SABA CT measures of attenuation, skew, and kurtosis were obtained from areas of lung tissue to assess EVLW Airway luminal areas and wall thicknesses were also measured : CT tissue density suggested increased EVLW in HF without differences in the ratio of airway wall thickness to luminal area or luminal area to TLC (skew: 2.85 ± 1.08 vs. 2.11 ± 0.79, P < 0.01; Kurtosis: 15.5 ± 9.5 vs. 9.3 ± 5.5 P < 0.01; control vs. HF). PFTs were decreased in HF at baseline (% predicted FVC:101 ± 15% vs. 83 ± 18%, P < 0.01;FEV1:103 ± 15% vs. 82 ± 19%, P < 0.01;FEF25-75: 118 ± 36% vs. 86 ± 36%, P < 0.01; control vs. HF). Airway luminal areas, but not CT measures, were correlated with PFTs at baseline. The SABA cleared EVLW and decreased airway wall thickness but did not change luminal area. Patients with HF had evidence of increased EVLW, but not an expanded bronchial circulation. Airway caliber was maintained relative to controls, despite reductions in lung volume and flow rates. SABA improved lung function, primarily by reducing EVLW.


Assuntos
Insuficiência Cardíaca/complicações , Pulmão/fisiopatologia , Edema Pulmonar/etiologia , Administração por Inalação , Agonistas de Receptores Adrenérgicos beta 2/administração & dosagem , Idoso , Albuterol/administração & dosagem , Estudos de Casos e Controles , Doença Crônica , Água Extravascular Pulmonar/metabolismo , Feminino , Volume Expiratório Forçado , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/fisiopatologia , Humanos , Pulmão/irrigação sanguínea , Pulmão/diagnóstico por imagem , Pulmão/efeitos dos fármacos , Masculino , Fluxo Máximo Médio Expiratório , Pessoa de Meia-Idade , Edema Pulmonar/diagnóstico , Edema Pulmonar/tratamento farmacológico , Edema Pulmonar/metabolismo , Edema Pulmonar/fisiopatologia , Volume Sistólico , Fatores de Tempo , Tomografia Computadorizada Espiral , Função Ventricular Esquerda , Capacidade Vital
3.
J Appl Physiol (1985) ; 121(2): 503-11, 2016 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-27402558

RESUMO

It is generally recommended that an esophageal balloon-catheter possess an adequate frequency response up to 15 Hz, such that parameters of respiratory mechanics may be quantified with precision. In our experience, however, we have observed that some commercially available systems do not display an ideal frequency response (<8-10 Hz). We therefore investigated whether the poor frequency response of a commercially available esophageal catheter may be adequately compensated using two numerical techniques: 1) an exponential model correction, and 2) Wiener deconvolution. These two numerical techniques were performed on a commercial balloon-catheter interfaced with 0, 1, and 2 lengths of extension tubing (90 cm each), referred to as configurations L0, L90, and L180, respectively. The frequency response of the balloon-catheter in these configurations was assessed by empirical transfer function analysis, and its "working" range was defined as the frequency beyond which more than 5% amplitude and/or phase distortion was observed. The working frequency range of the uncorrected balloon-catheter extended up to only 10 Hz for L0, and progressively worsened with additional tubing length (L90 = 3 Hz, L180 = 2 Hz). Although both numerical methods of correction adequately enhanced the working frequency range of the balloon-catheter to beyond 25 Hz for all length configurations (L0, L90, and L180), Wiener deconvolution consistently provided more accurate corrections. Our data indicate that Wiener deconvolution provides a superior correction of the balloon-catheter's dynamic response, and is relatively more robust to extensions in catheter tube length compared with the exponential correction method.


Assuntos
Algoritmos , Artefatos , Cateteres , Esôfago/fisiologia , Manometria/instrumentação , Mecânica Respiratória/fisiologia , Diagnóstico por Computador/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Análise de Fourier , Análise Numérica Assistida por Computador , Pressão , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
4.
J Appl Physiol (1985) ; 113(6): 872-7, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22773767

RESUMO

Functional values of LogSD of the ventilation distribution (σ(V)) have been reported previously, but functional values of LogSD of the perfusion distribution (σ(q)) and the coefficient of correlation between ventilation and perfusion (ρ) have not been measured in humans. Here, we report values for σ(V), σ(q), and ρ obtained from wash-in data for three gases, helium and two soluble gases, acetylene and dimethyl ether. Normal subjects inspired gas containing the test gases, and the concentrations of the gases at end-expiration during the first 10 breaths were measured with the subjects at rest and at increasing levels of exercise. The regional distribution of ventilation and perfusion was described by a bivariate log-normal distribution with parameters σ(V), σ(q), and ρ, and these parameters were evaluated by matching the values of expired gas concentrations calculated for this distribution to the measured values. Values of cardiac output and LogSD ventilation/perfusion (Va/Q) were obtained. At rest, σ(q) is high (1.08 ± 0.12). With the onset of ventilation, σ(q) decreases to 0.85 ± 0.09 but remains higher than σ(V) (0.43 ± 0.09) at all exercise levels. Rho increases to 0.87 ± 0.07, and the value of LogSD Va/Q for light and moderate exercise is primarily the result of the difference between the magnitudes of σ(q) and σ(V). With known values for the parameters, the bivariate distribution describes the comprehensive distribution of ventilation and perfusion that underlies the distribution of the Va/Q ratio.


Assuntos
Pulmão/irrigação sanguínea , Oxigênio/sangue , Circulação Pulmonar , Ventilação Pulmonar , Relação Ventilação-Perfusão , Acetileno/administração & dosagem , Administração por Inalação , Testes Respiratórios , Débito Cardíaco , Teste de Esforço , Expiração , Hélio/administração & dosagem , Humanos , Inalação , Éteres Metílicos/administração & dosagem , Modelos Biológicos , Valores de Referência , Fluxo Sanguíneo Regional
6.
Eur Respir J ; 39(6): 1449-57, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22034652

RESUMO

Patients with heart failure (HF) display numerous derangements in ventilatory function, which together serve to increase the work of breathing (W(b)) during exercise. However, the extent to which the resistive and elastic properties of the respiratory system contribute to the higher W(b) in these patients is unknown. We quantified the resistive and elastic W(b) in patients with stable HF (n = 9; New York Heart Association functional class I-II) and healthy control subjects (n = 9) at standardised levels of minute ventilation (V'(E)) during graded exercise. Dynamic lung compliance was systematically lower for a given level of V'(E) in HF patients than controls (p<0.05). HF patients displayed slightly higher levels of inspiratory elastic W(b) with greater amounts of ventilatory constraint and resistive W(b) than control subjects during exercise (p<0.05). Our data indicates that the higher W(b) in HF patients is primarily due to a greater resistive, rather than elastic, load to breathing. The greater resistive W(b) in these patients probably reflects an increased hysteresivity of the airways and lung tissues. The marginally higher inspiratory elastic W(b) observed in HF patients appears related to a combined decrease in the compliances of the lungs and chest wall. The clinical and physiological implications of our findings are discussed.


Assuntos
Exercício Físico/fisiologia , Insuficiência Cardíaca/fisiopatologia , Trabalho Respiratório/fisiologia , Doença Crônica , Elasticidade , Teste de Esforço , Feminino , Humanos , Pulmão/fisiopatologia , Complacência Pulmonar/fisiologia , Masculino , Pessoa de Meia-Idade
7.
Artigo em Inglês | MEDLINE | ID: mdl-21695160

RESUMO

INTRODUCTION: Each year, the US Antarctic Program rapidly transports scientists and support personnel from sea level (SL) to the South Pole (SP, 2835 m) providing a unique natural laboratory to quantify the incidence of acute mountain sickness (AMS), patterns of altitude related symptoms and the field effectiveness of acetazolamide in a highly controlled setting. We hypothesized that the combination of rapid ascent (3 hr), accentuated hypobarism (relative to altitude), cold, and immediate exertion would increase altitude illness risk. METHODS: Medically screened adults (N = 246, age = 37 ± 11 yr, 30% female, BMI = 26 ± 4 kg/m(2)) were recruited. All underwent SL and SP physiological evaluation, completed Lake Louise symptom questionnaires (LLSQ, to define AMS), and answered additional symptom related questions (eg, exertional dyspnea, mental status, cough, edema and general health), during the 1st week at altitude. Acetazolamide, while not mandatory, was used by 40% of participants. RESULTS: At SP, the barometric pressure resulted in physiological altitudes that approached 3400 m, while T °C averaged -42, humidity 0.03%. Arterial oxygen saturation averaged 89% ± 3%. Overall, 52% developed LLSQ defined AMS. The most common symptoms reported were exertional dyspnea-(87%), sleeping difficulty-(74%), headache-(66%), fatigue-(65%), and dizziness/lightheadedness-(46%). Symptom severity peaked on days 1-2, yet in >20% exertional dyspnea, fatigue and sleep problems persisted through day 7. AMS incidence was similar between those using acetazolamide and those abstaining (51 vs. 52%, P = 0.87). Those who used acetazolamide tended to be older, have less altitude experience, worse symptoms on previous exposures, and less SP experience. CONCLUSION: The incidence of AMS at SP tended to be higher than previously reports in other geographic locations at similar altitudes. Thus, the SP constitutes a more intense altitude exposure than might be expected considering physical altitude alone. Many symptoms persist, possibly due to extremely cold, arid conditions and the benefits of acetazolamide appeared negligible, though it may have prevented more severe symptoms in higher risk subjects.

8.
J Appl Physiol (1985) ; 109(3): 643-53, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20538842

RESUMO

Key elements for determining alveolar-capillary membrane conductance (Dm) and pulmonary capillary blood volume (Vc) from the lung diffusing capacity (Dl) for carbon monoxide (DlCO) or for nitric oxide (DlNO) are the reaction rate of carbon monoxide with hemoglobin (thetaCO) and the DmCO/DlNO relationship (alpha-ratio). Although a range of values have been reported, currently there is no consensus regarding these parameters. The study purpose was to define optimal parameters (thetaCO, alpha-ratio) that would experimentally substantiate calculations of Dm and Vc from the single-inspired O2 tension [inspired fraction of O2 (FiO2)] method relative to the multiple-FiO2 method. Eight healthy men were studied at rest and during moderate exercise (80-W cycle). Dm and Vc were determined by the multiple-FiO2 and single-FiO2 methods (rebreathe technique) and were tabulated by applying previously reported thetaCO equations (both methods) and by varying the alpha-ratio (single-FiO2 method) from 1.90 to 2.50. Values were then compared between methods throughout the examined alpha-ratios. Dm and Vc were critically dependent on the applied thetaCO equation. For the multiple-FiO2 method, Dm was highly variable between thetaCO equations (rest and exercise); the range of Vc was less widespread. For the single-FiO2 method, the thetaCO equation by Reeves and Park (1992) combined with an alpha-ratio between 2.08 and 2.26 gave values for Dm and Vc that most closely matched those from the multiple-FiO2 method and were also physiologically plausible compared with predicted values. We conclude that the parameters used to calculate Dm and Vc values from the single-FiO2 method (using DlCO and DlNO) can significantly influence results and should be evaluated within individual laboratories to obtain optimal values.


Assuntos
Volume Sanguíneo , Inalação , Microcirculação , Oxigênio/administração & dosagem , Alvéolos Pulmonares/irrigação sanguínea , Circulação Pulmonar , Capacidade de Difusão Pulmonar , Administração por Inalação , Adolescente , Adulto , Capilares/fisiologia , Permeabilidade Capilar , Monóxido de Carbono/administração & dosagem , Monóxido de Carbono/sangue , Exercício Físico , Hemoglobinas/metabolismo , Humanos , Masculino , Modelos Biológicos , Óxido Nítrico/administração & dosagem , Óxido Nítrico/sangue , Oxigênio/sangue , Reprodutibilidade dos Testes , Descanso , Fatores de Tempo , Adulto Jovem
9.
Respir Physiol Neurobiol ; 171(1): 22-30, 2010 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-20085827

RESUMO

The purpose of this study was to compare the repeatability (2.77 multiplied by the within-subject SD)between two different rebreathing protocols on cardiac output ( ˙Q ), pulmonary diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO), and pulmonary capillary blood volume (Vc). This study compared two bag volume protocols [Fixed Bag Volume (FBV) = bag volume fixed at 60% of forced vital capacity; Dynamic Bag Volume (DBV) = bag volume matched to tidal volume at each stage of exercise].Ten females (age = 27±8 yrs; ˙VO2, (peak)=2.5±0.6 L/min had measurements at rest (12%), 52%, 88%, and 100% of ˙VO2, (peak) on two study days. Neither the slope nor intercept of ˙Q vs. ˙VO2 were different between either bag volume protocols. The slope of DLCO vs. ˙Q was the same but the intercept was higher for the FBV protocol. The bag volume affected the slope and the intercept between DLNO vs. ˙Q (p < 0.05).The mean repeatability was similar between both protocols for ˙Q (2.0 vs. 2.3 L/min) and DLCO (3.8 vs.5.9 mL/min/mmHg), regardless of exercise intensity. Increasing exercise intensity made the measurement error worse for Vc and DLNO (p ≤ 0.06). Measurement error was lower for Vc when using the FBV protocol (p = 0.02). Also, the pattern of bag volume used during rebreathing maneuvers affected the relation between DLNO vs. ˙Q more than it affected DLCO vs. ˙Q , or Vc vs. ˙Q. Additionally, the FBV protocol provided less measurement error for Vc compared to the DBV protocol [corrected].


Assuntos
Débito Cardíaco/fisiologia , Capacidade de Difusão Pulmonar , Mecânica Respiratória/fisiologia , Adulto , Monóxido de Carbono/sangue , Exercício Físico , Teste de Esforço/métodos , Feminino , Humanos , Pessoa de Meia-Idade , Óxido Nítrico/sangue , Oxigênio/sangue , Consumo de Oxigênio , Análise de Regressão , Testes de Função Respiratória/métodos , Descanso , Adulto Jovem
10.
J Appl Physiol (1985) ; 108(3): 483-9, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19959767

RESUMO

We evaluated the influence of age and sex on the relationship between central and peripheral vasodilatory capacity. Healthy men (19 younger, 12 older) and women (17 younger, 17 older) performed treadmill and knee extensor exercise to fatigue on separate days while maximal cardiac output (Q, acetylene uptake) and peak femoral blood flow (FBF, Doppler ultrasound) were measured, respectively. Maximal Q was reduced with age similarly in men (Y: 23.6 +/- 2.7 vs. O: 17.4 +/- 3.5 l/min; P < 0.05) and women (Y: 17.7 +/- 1.9 vs. O: 12.3 +/- 1.6 l/min; P < 0.05). Peak FBF was similar between younger (Y) and older (O) men (Y: 2.1 +/- 0.5 vs. O: 2.2 +/- 0.7 l/min) but was lower in older women compared with younger women (Y: 1.9 +/- 0.4 vs. O: 1.4 +/- 0.4 l/min; P < 0.05). Maximal Q was positively correlated with peak FBF in men (Y: r = 0.55, O: r = 0.74; P < 0.05) but not in women (Y: r = 0.34, O: r = 0.10). Normalization of cardiac output to appendicular muscle mass and peak FBF to quadriceps mass reduced the correlation between these variables in younger men (r = 0.30), but the significant association remained in older men (r = 0.68; P < 0.05), with no change in women. These data suggest that 1) aerobic capacity is associated with peripheral vascular reserve in men but not women, and 2) aging is accompanied by a more pronounced sex difference in this relationship.


Assuntos
Envelhecimento , Débito Cardíaco , Tolerância ao Exercício , Artéria Femoral/fisiologia , Músculo Quadríceps/irrigação sanguínea , Vasodilatação , Adaptação Fisiológica , Adulto , Fatores Etários , Idoso , Teste de Esforço , Feminino , Artéria Femoral/diagnóstico por imagem , Humanos , Masculino , Pessoa de Meia-Idade , Contração Muscular , Fadiga Muscular , Consumo de Oxigênio , Fatores Sexuais , Ultrassonografia Doppler , Adulto Jovem
11.
Eur J Appl Physiol ; 106(4): 621-7, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19381678

RESUMO

Circulation time (the transit time for a bolus of blood through the circulatory system) is a potential index of cardiac dysfunction in chronic heart failure (HF). In healthy subjects, circulation time falls as cardiac output (Q) rises during exercise, however little is known about this index in HF. In this study we examined the relationship between lung-to-lung circulation time (LLCT) during exercise in ten HF (53 +/- 14 year, resting ejection fraction = 23 +/- 8%) and control subjects (51 +/- 18 year). We hypothesized that HF patients would have slower LLCT times during exercise when compared to control subjects. Each subject completed two identical incremental exercise tests during which LLCT was measured in one test and Q measured in the other. Q was measured using the open circuit C(2)H(2) washin technique and circulation time measured using an inert gas technique. In HF patients and control subjects, LLCT decreased and Q increased from rest (HF:LLCT = 53.6 +/- 8.2 s, Q = 4.3 +/- 1.1 l min(-1); control: LLCT = 55.3 +/- 10.9 s, Q = 4.5 +/- 0.5 l min(-1)) to peak exercise (HF:LLCT = 20.6 +/- 3.9* s, Q = 8.8 +/- 2.5* l min(-1); control:LLCT = 14.9 +/- 2.4 s, Q = 16.5 +/- 1.2 l min(-1); *P < 0.05 vs control). LLCT was significantly (P < 0.05) slower for the HF group when compared to the control group during submaximal exercise and at peak exercise. However, at a fixed Q the HF subjects had a faster LLCT. We hypothesize that the faster LLCT at a fixed Q for HF patients, may be the result of a more intensive peripheral vasoconstriction of non-active beds and a better redistribution of blood flow.


Assuntos
Insuficiência Cardíaca/fisiopatologia , Pulmão/irrigação sanguínea , Pulmão/fisiopatologia , Esforço Físico , Circulação Pulmonar , Tempo de Circulação Sanguínea , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
12.
Respir Physiol Neurobiol ; 162(3): 204-9, 2008 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-18647664

RESUMO

This study examined the relationship between airway blood flow (Q(aw)), ventilation (V(E)) and cardiac output (Q(tot)) during exercise in healthy humans (n=12, mean age 34+/-11 yr). Q(aw) was estimated from the uptake of the soluble gas dimethyl ether while V(E) and Q(tot) were measured using open circuit spirometry. Measurements were made prior to and during exercise at 34+/-5 W (Load 1) and 68+/-10 W (Load 2) and following the cessation of exercise (recovery). Q(aw) increased in a stepwise fashion (P<0.05) from rest (52.8+/-19.5 microl min(-1) ml(-1)) to exercise at Load 1 (67.0+/-20.3 microl min(-1) ml(-1)) and Load 2 (84.0+/-22.9 microl min(-1) ml(-1)) before returning to pre-exercise levels in recovery (51.7+/-13.2 microl min(-1) ml(-1)). Q(aw) was positively correlated with both Q(tot) (r=0.58, P<0.01) and V(E) (r=0.50, P<0.01). These results demonstrate that the increase in Q(aw) is linked to an exercise related increase in both Q(tot) and V(E) and may be necessary to prevent excessive airway cooling and drying.


Assuntos
Débito Cardíaco/fisiologia , Exercício Físico/fisiologia , Circulação Pulmonar/fisiologia , Ventilação Pulmonar/fisiologia , Respiração , Adulto , Análise de Variância , Feminino , Humanos , Masculino , Consumo de Oxigênio , Troca Gasosa Pulmonar , Fluxo Sanguíneo Regional/fisiologia , Respiração Artificial , Resistência Vascular/fisiologia , Adulto Jovem
13.
J Card Fail ; 13(5): 389-94, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17602986

RESUMO

BACKGROUND: Peak exercise capacity (VO2peak) is a measure of the severity of chronic heart failure (CHF); however, few indices of resting cardiopulmonary function have been shown to predict VO2peak. A prolonged circulation time has been suggested as an index of increased severity of CHF. The aim of this study was to investigate the relationship between resting lung-to-lung circulation time (LLCT) and VO2peak in CHF. METHODS AND RESULTS: Thirty CHF patients (59 +/- 13 years, New York Heart Association: 1.9 +/- 1.0) undertook the study. Each subject completed resting pulmonary and echocardiography measures and an incremental exercise test. LLCT was measured using the reappearance of end-tidal acetylene (P(ET),C2H2) after a single inhalation. Univariate and multivariate stepwise linear regression was used to determine the predictors of VO2peak. Univariate correlates of VO2peak (group mean 1.53 +/- 0.44 L/min(-1)) included LLCT (r = -0.75), inspiratory capacity (r = 0.41), ejection fraction (r = 0.33), peak early flow velocity (r = -0.39), and the ratio of early to late flow velocity (r = -0.31). LLCT was the only independent predictor where VO(2peak) = 3.923-0.045 (LLCT); r2 = 54%. CONCLUSIONS: These results suggest that resting LLCT determined using the soluble inert gas technique represents a simple, noninvasive method that provides additional information regarding exercise capacity in CHF.


Assuntos
Insuficiência Cardíaca/fisiopatologia , Consumo de Oxigênio/fisiologia , Circulação Pulmonar/fisiologia , Acetileno/farmacocinética , Idoso , Débito Cardíaco/fisiologia , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Índice de Gravidade de Doença
14.
J Card Fail ; 13(2): 100-7, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17395049

RESUMO

BACKGROUND: This study examined the influence of increased cardiac size on maximal lung volumes, forced expiratory airflows, and the diffusing capacity of the lungs in heart failure (HF) patients compared with controls. METHODS AND RESULTS: Forty-one HF patients of New York Heart Association (NYHA) class: Group A = class I/II (n = 26) and Group B = class III/IV (n = 15) and an equal number matched controls (CTL) were recruited. Participants underwent echocardiography, spirometry, and posteroanterior and lateral chest radiographic evaluation (RAD) for volumetric estimation of the total thoracic cavity (TTC), diaphragm, heart, and lungs. Analysis of variance demonstrated no difference between groups for TTC volume (P = .63). RAD cardiac volumes (% TTC volume) were significantly different among all groups (P < .001). Echocardiograms determined left ventricular mass was elevated in the HF groups compared with the CTL group (P < .001) with no difference between HF groups. Lung volume (% TTC volume) was reduced as a function of disease severity (P < .001). RAD measures of cardiac volume demonstrated the strongest relationship with restrictive lung alterations (t-statistic = -5.627, P < .001 and t-statistic = -4.378, P < .001 for forced vital capacity and forced expiratory volume in 1 second, respectively). CONCLUSIONS: These results suggest cardiac size may pose significant constraints on the lungs and likely plays a major role in the restrictive breathing patterns often reported in HF patients.


Assuntos
Fluxo Expiratório Forçado/fisiologia , Insuficiência Cardíaca/fisiopatologia , Pulmão/fisiopatologia , Capacidade de Difusão Pulmonar/fisiologia , Progressão da Doença , Ecocardiografia Doppler , Feminino , Insuficiência Cardíaca/diagnóstico por imagem , Humanos , Pulmão/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Prognóstico , Radiografia Torácica , Estudos Retrospectivos , Índice de Gravidade de Doença , Volume Sistólico/fisiologia
15.
J Appl Physiol (1985) ; 102(6): 2172-8, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17347382

RESUMO

The beta2-adrenergic receptors (beta2AR) play an important role in lung fluid regulation. Previous research has suggested that subjects homozygous for arginine at amino acid 16 of the beta2AR (Arg16) may have attenuated receptor function relative to subjects homozygous for glycine at the same amino acid (Gly16). We sought to determine if the Arg16Gly polymorphism of the beta2AR influenced lung fluid balance in response to rapid saline infusion. We hypothesized that subjects homozygous for Arg at amino acid 16 (n=14) would have greater lung fluid accumulation compared with those homozygous for Gly (n=15) following a rapid intravenous infusion of isotonic saline (30 ml/kg over 17 min). Changes in lung fluid were determined using measures of lung density and tissue volume (computerized tomography imaging) and measures of pulmonary capillary blood volume (Vc) and alveolar-capillary conductance (DM, determined from the simultaneous assessment of the diffusing capacities of the lungs for carbon monoxide and nitric oxide). The saline infusion resulted in elevated catecholamines in both genotype groups (Arg16 283+/-117% vs. Gly16 252+/-118%, P>0.05). The Arg16 group had a larger decrease in DM and increase in lung tissue volume and lung water after saline infusion relative to the Gly16 group (DM -13+/-14 vs. 0+/-26%, P<0.05; lung tissue volume 13+/-11 vs. 3+/-11% and lung water +90+/-66 vs. +48+/-144 ml, P=0.10, P<0.05, for Arg vs. Gly16, respectively, means+/-SD). These data suggest that subjects homozygous for Arg at amino acid 16 of the beta2AR have a greater susceptibility for lung fluid accumulation relative to subjects homozygous for Gly at this position.


Assuntos
Líquidos Corporais/metabolismo , Pulmão/fisiologia , Receptores Adrenérgicos beta 2/genética , Equilíbrio Hidroeletrolítico/genética , Adulto , Feminino , Variação Genética/genética , Humanos , Masculino , Estatística como Assunto
17.
J Appl Physiol (1985) ; 102(4): 1535-44, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17122371

RESUMO

Xenon computed tomography (Xe-CT) is used to estimate regional ventilation by measuring regional attenuation changes over multiple breaths while rebreathing a constant Xe concentration ([Xe]). Xe-CT has potential human applications, although anesthetic properties limit [Xe] to

Assuntos
Criptônio , Pulmão/diagnóstico por imagem , Pulmão/fisiopatologia , Troca Gasosa Pulmonar/fisiologia , Ventilação Pulmonar/fisiologia , Intensificação de Imagem Radiográfica/métodos , Tomografia Computadorizada por Raios X/métodos , Xenônio , Administração por Inalação , Animais , Criptônio/administração & dosagem , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Ovinos , Xenônio/administração & dosagem
18.
Am Heart J ; 153(1): 104.e1-7, 2007 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17174646

RESUMO

BACKGROUND: Patients with heart failure (HF) display a number of breathing abnormalities including periodic breathing (PB) at rest. Although the mechanism(s) contributing to PB remain unclear, we examined whether changes in pulmonary wedge pressure (PWP) and pulmonary vascular resistance (PVR) alter PB in patients with established HF. METHODS: We studied 12 male patients with HF (age, 50 +/- 11 years; ejection fraction, 18.3 +/- 3.8 %; New York Heart Association class, 3.2 +/- 0.4), with PB at rest, who are undergoing right heart catheterization with infusion of nitroprusside. RESULTS: At baseline, patients with HF displayed minute ventilation (V(E)) oscillations with amplitude of 5.5 +/- 2.7 L/min (57 +/- 34% of the average V(E)) and cycle length of 61 +/- 18 seconds. Cardiac index (CI), PVR, and mean PWP averaged 2.0 +/- 0.4 L min(-1) m(-2), 281.9 +/- 214.9 dyne/s per cm(-5), and 28.3 +/- 5.4 mm Hg, respectively. During nitroprusside infusion, CI increased to 3.1 +/- 0.6 L min(-1) m(-2), PVR decreased to 163.9 +/- 85.2 dyne/s per cm(-5), and PWP fell to 10.0 +/- 4.2 mm Hg. Nitroprusside reduced the amplitude (2.6 +/- 2.4 L/min, 23 +/- 21% of average V(E); P < .01) and cycle length (41.4 +/- 28.8 seconds; P < .01) of V(E) oscillations while abolishing oscillations in 3 patients. Although average V(E) and PaCO2 remained unchanged, there was a significant increase in the ratio of tidal volume to inspiratory time (V(T)/T(I); P < .01), suggesting an increase in ventilatory drive. The change in the amplitude of V(E) oscillations was positively correlated with the change in PWP (r = 0.75; P < .01), negatively correlated with the change in PVR (r = 0.63; P < .05), and not correlated with the change in CI. CONCLUSIONS: These data suggest that PWP (left atrial pressure) may play a direct role in the PB observed in HF at rest.


Assuntos
Insuficiência Cardíaca/fisiopatologia , Nitroprussiato/farmacologia , Pressão Propulsora Pulmonar/efeitos dos fármacos , Respiração/efeitos dos fármacos , Vasodilatadores/farmacologia , Adulto , Pressão Sanguínea/efeitos dos fármacos , Cateterismo Cardíaco , Débito Cardíaco , Frequência Cardíaca/efeitos dos fármacos , Humanos , Masculino , Pessoa de Meia-Idade , Oxigênio/sangue , Consumo de Oxigênio , Troca Gasosa Pulmonar , Resistência Vascular/efeitos dos fármacos
19.
Pediatr Pulmonol ; 41(11): 1095-102, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16986167

RESUMO

INTRODUCTION: The standard technique for assessing pulmonary diffusing capacity of the lungs (DL) for carbon monoxide (CO) is the single breath (SB) technique. SB_DLco in children can be problematic because it requires a vital capacity >1.5 L. We have developed an open-circuit technique (OC), which uses the wash-in of CO over a series of 8-10 normal breaths that does not require rebreathing. In this study, we compared the SB_DLco against the OC_DLco. METHODS: Nineteen healthy children between 7 and 18 years performed SB_DLco and OC_DLco tests. The mean SB_DLco was significantly larger than the mean OC_DLco. The mean difference OC_DLco minus SB_ DLco was: -2.92 +/- 4.21 ml/min/mm Hg, though the difference was negatively correlated with the mean of the two (r = 0.73). The lower mean OC_DLco was in part due to lower lung volume (as measured by alveolar volume (VA)) during the maneuver. In both groups there was a positive correlation between VA and DLco, and the mean VA was -2.17 +/- 1.07 L lower using OC compared to SB. The difference was again negatively correlated with the mean (r = 0.82). The mean OC minus SB difference in DLco/VA was: 6.06 +/- 1.98 ml/min/mm Hg/L, though this difference was positively correlated with the mean, r = 0.76. CONCLUSIONS: We found a good correlation between both techniques for DLco, VA, and DLco/VA. The OC offers the advantage of minimal subject cooperation, and may be preferable to use in children.


Assuntos
Monóxido de Carbono/metabolismo , Capacidade de Difusão Pulmonar/fisiologia , Testes de Função Respiratória/métodos , Adolescente , Criança , Feminino , Humanos , Masculino , Alvéolos Pulmonares/fisiologia
20.
J Appl Physiol (1985) ; 101(6): 1623-32, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16902060

RESUMO

Hypoxia and hypoxic exercise increase pulmonary arterial pressure, cause pulmonary capillary recruitment, and may influence the ability of the lungs to regulate fluid. To examine the influence of hypoxia, alone and combined with exercise, on lung fluid balance, we studied 25 healthy subjects after 17-h exposure to 12.5% inspired oxygen (barometric pressure = 732 mmHg) and sequentially after exercise to exhaustion on a cycle ergometer with 12.5% inspired oxygen. We also studied subjects after a rapid saline infusion (30 ml/kg over 15 min) to demonstrate the sensitivity of our techniques to detect changes in lung water. Pulmonary capillary blood volume (Vc) and alveolar-capillary conductance (D(M)) were determined by measuring the diffusing capacity of the lungs for carbon monoxide and nitric oxide. Lung tissue volume and density were assessed using computed tomography. Lung water was estimated by subtracting measures of Vc from computed tomography lung tissue volume. Pulmonary function [forced vital capacity (FVC), forced expiratory volume after 1 s (FEV(1)), and forced expiratory flow at 50% of vital capacity (FEF(50))] was also assessed. Saline infusion caused an increase in Vc (42%), tissue volume (9%), and lung water (11%), and a decrease in D(M) (11%) and pulmonary function (FVC = -12 +/- 9%, FEV(1) = -17 +/- 10%, FEF(50) = -20 +/- 13%). Hypoxia and hypoxic exercise resulted in increases in Vc (43 +/- 19 and 51 +/- 16%), D(M) (7 +/- 4 and 19 +/- 6%), and pulmonary function (FVC = 9 +/- 6 and 4 +/- 3%, FEV(1) = 5 +/- 2 and 4 +/- 3%, FEF(50) = 4 +/- 2 and 12 +/- 5%) and decreases in lung density and lung water (-84 +/- 24 and -103 +/- 20 ml vs. baseline). These data suggest that 17 h of hypoxic exposure at rest or with exercise resulted in a decrease in lung water in healthy humans.


Assuntos
Água Extravascular Pulmonar/metabolismo , Hipóxia/fisiopatologia , Resistência Física , Esforço Físico , Descanso , Adulto , Feminino , Humanos , Masculino , Valores de Referência
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