Reliability and Physiological Interpretation of Pulmonary Gas Exchange by "Circulatory Equivalents" in Chronic Heart Failure.
J Am Heart Assoc
; 7(7)2018 03 27.
Article
em En
| MEDLINE
| ID: mdl-29588313
ABSTRACT
BACKGROUND:
Peak ratios of pulmonary gas-exchange to ventilation during exercise (VËO2/VËE and VËCO2/VËE, termed "circulatory equivalents") are sensitive to heart failure (HF) severity, likely reflecting low and/or poorly distributed pulmonary perfusion. We tested whether peak VËO2/VËE and VËCO2/VËE would (1) distinguish HF patients from controls; (2) be independent of incremental exercise protocol; and (3) correlate with lactate threshold (LT) and ventilatory compensation point (VCP), respectively. METHODS ANDRESULTS:
Twenty-four HF patients (61±11 years) with reduced ejection fraction (31±8%) and 11 controls (63±7 years) performed ramp-incremental cycle ergometry. Eighteen HF patients also performed slow (5±1 W/min), medium (9±4 W/min), and fast (19±6 W/min) ramps. Peak VËO2/VËE and VËCO2/VËE from X-Y plot, and LT and VCP from 9-panel plot, were determined by 2 independent, blinded, assessors. Peak VËO2/VËE (31.2±4.4 versus 41.8±4.8 mL/L; P<0.0001) and VËCO2/VËE (29.3±3.0 versus 36.9±4.0 mL/L; P<0.0001) were lower in HF than controls. Within individuals, there was no difference across 3 ramp rates in peak VËO2/VËE (P=0.62) or VËCO2/VËE (P=0.97). Coefficient of variation (CV) in peak VËO2/VËE was lower than for LT (5.1±2.1% versus 8.2±3.7%; P=0.014), and coefficient of variation in peak VËCO2/VËE was lower than for VCP (3.3±1.8% versus 8.7±4.2%; P<0.001). In all participants, peak VËO2/VËE was correlated with, but occurred earlier than, LT (r2=0.94; mean bias, -0.11 L/min), and peak VËCO2/VËE was correlated with, but occurred earlier than, VCP (r2=0.98; mean bias -0.08 L/min).CONCLUSIONS:
Peak circulatory equivalents during exercise are strongly associated with (but not identical to) LT and VCP. Peak circulatory equivalents are reliable, objective, effort-independent indices of gas-exchange abnormality in HF.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Troca Gasosa Pulmonar
/
Circulação Pulmonar
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Tolerância ao Exercício
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Ventilação Pulmonar
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Insuficiência Cardíaca
/
Pulmão
Tipo de estudo:
Diagnostic_studies
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Observational_studies
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Risk_factors_studies
Limite:
Aged
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Female
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Humans
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Male
/
Middle aged
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article