RESUMO
Peak oxygen pulse has been considered a surrogate of cardiovascular function and an independent predictor of all cause mortality. However, O2P(peak) depends on maximal volitional effort which may limit its utility in older subjects. The aim of this study was to develop a model to estimate O2P(peak) without exercise in an elderly sample. This cross-sectional study enrolled 67 community-dwelling older adults (69.4±7.1 years; 41 men) for the non-exercise model development and 30 community-dwelling older adults (67.7±6.4 years; n=30; 17 men) for cross-validation. The non-exercise model was derived through hierarchical regression model and cross-validated by means of PRESS statistics and comparison against an independent sample. Classification accuracy of the model for tertiles of estimated and actual O2P(peak) was tested by gamma (γ) nonparametric correlation. The following prediction equation was generated: -3.416+0.137 × weight (kg)+1.226 × Veterans Specific Activity Questionnaire (VSAQ) (metabolic equivalents, METs)+1.987 × gender (0=women, 1=men)-2.045 × ß-Blockers use (0=no, 1=yes)-0.044 × resting heart rate (HR) (R(2)=0.83; standard error of estimate (SEE)=1.68 mL beat(-1)). Correlation in cross-validation group was 0.80 (P<0.001). A high probability was observed for the model to rank the values in the same tertile in validation and cross-validation groups (γ=0.98; γ=0.92, respectively, P<0.05). In conclusion, O2P(peak) can be estimated with reasonable precision without exercise testing, providing an alternative for elder subjects not capable to perform maximal effort.
Assuntos
Frequência Cardíaca/fisiologia , Modelos Estatísticos , Consumo de Oxigênio/fisiologia , Pulso Arterial , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Análise de Regressão , Reprodutibilidade dos Testes , Inquéritos e QuestionáriosRESUMO
OBJECTIVE: To examine the association between cardiac performance during recovery and the severity of heart failure, as determined by clinical and cardiopulmonary exercise test responses. METHODS: As part of a retrospective cohort study, 46 heart failure patients and 13 normal subjects underwent cardiopulmonary exercise testing while cardiac output was measured using a noninvasive device. Cardiac output in recovery was expressed as the slope of a single exponential relationship between cardiac output and time; the recovery-time constant was assessed in relation to indices of cardiac function, along with clinical, functional, and cardiopulmonary exercise responses. RESULTS: The recovery time constant was delayed in patients with heart failure compared with normal subjects (296.7 ± 238 vs. 110.1 ±27 seconds, p <0.01), and the slope of the decline of cardiac output in recovery was steeper in normal subjects compared with heart failure patients (p<0.001). The slope of the decline in cardiac output recovery was inversely related to peak VO(2) (r = -0.72, p<0.001) and directly related to the VE/VCO(2) slope (r = 0.57, p,0.001). Heart failure patients with abnormal recovery time constants had lower peak VO(2), lower VO(2) at the ventilatory threshold, lower peak cardiac output, and a heightened VE/VCO(2) slope during exercise. CONCLUSIONS: Impaired cardiac output recovery kinetics can identify heart failure patients with more severe disease, lower exercise capacity, and inefficient ventilation. Estimating cardiac output in recovery from exercise may provide added insight into the cardiovascular status of patients with heart failure.
Assuntos
Adaptação Fisiológica/fisiologia , Débito Cardíaco/fisiologia , Exercício Físico/fisiologia , Insuficiência Cardíaca/fisiopatologia , Métodos Epidemiológicos , Teste de Esforço/métodos , Humanos , Cinética , Pessoa de Meia-Idade , Monitorização Fisiológica/métodos , Consumo de Oxigênio/fisiologia , Termodiluição/métodos , Fatores de TempoRESUMO
OBJECTIVE: To examine the association between cardiac performance during recovery and the severity of heart failure, as determined by clinical and cardiopulmonary exercise test responses. METHODS: As part of a retrospective cohort study, 46 heart failure patients and 13 normal subjects underwent cardiopulmonary exercise testing while cardiac output was measured using a noninvasive device. Cardiac output in recovery was expressed as the slope of a single exponential relationship between cardiac output and time; the recovery-time constant was assessed in relation to indices of cardiac function, along with clinical, functional, and cardiopulmonary exercise responses. RESULTS: The recovery time constant was delayed in patients with heart failure compared with normal subjects (296.7 + 238 vs. 110.1 +27 seconds, p <0.01), and the slope of the decline of cardiac output in recovery was steeper in normal subjects compared with heart failure patients (p,0.001). The slope of the decline in cardiac output recovery was inversely related to peak VO2 (r = -0.72, p<0.001) and directly related to the VE/VCO2 slope (r = 0.57, p,0.001). Heart failure patients with abnormal recovery time constants had lower peak VO2, lower VO2 at the ventilatory threshold, lower peak cardiac output, and a heightened VE/VCO2 slope during exercise. CONCLUSIONS: Impaired cardiac output recovery kinetics can identify heart failure patients with more severe disease, lower exercise capacity, and inefficient ventilation. Estimating cardiac output in recovery from exercise may provide added insight into the cardiovascular status of patients with heart failure.