Milani R V, Mehra M R, Reddy T K, Lavie C J, Ventura H O
Department of Internal Medicine, Ochsner Heart and Vascular Institute, Ochsner Medical Institutions, New Orleans, Louisians 70121, USA.
Heart. 1996 Nov;76(5):393-6. doi: 10.1136/hrt.76.5.393.
To evaluate whether changes in the ventilation/carbon dioxide production ratio during early exercise could reliably serve as a surrogate marker for maximal oxygen consumption in heart failure patients. Maximal oxygen consumption is an important determinant of the severity of congestive heart failure with values > 14 ml/kg/min conferring a good 2-year survival. However, many patients undergoing cardiopulmonary exercise testing cannot exercise maximally because of other functional limitations.
Ventilation/carbon dioxide production ratio was assessed at rest, anaerobic threshold, and peak exercise in 75 patients with chronic heart failure and in 12 healthy controls. Patients were divided into two groups on the basis of heart failure severity as judged by maximal oxygen consumption.
Patients with mild-moderate heart failure had a 20% reduction in the ventilation/carbon dioxide production ratio at anaerobic threshold similar to that in healthy controls. Patients with severe heart failure failed to reduce this ratio at anaerobic threshold. Furthermore, a reduction in the ventilation/carbon dioxide production ratio in early exercise of less than 10% predicted a maximal oxygen consumption of < 14 ml/kg/min with a positive predictive value of 96% and a negative predictive value of 88%.
A reduction of the ventilation/carbon dioxide production ratio of less then 10% with early exercise reliably predicts poor functional capacity in congestive heart failure. Changes in this ratio during early exercise may be used as a surrogate for maximal oxygen consumption in patients who cannot exercise maximally.
评估早期运动期间通气/二氧化碳产生比值的变化是否能可靠地作为心力衰竭患者最大摄氧量的替代指标。最大摄氧量是充血性心力衰竭严重程度的重要决定因素，数值>14 ml/kg/min提示2年生存率良好。然而，许多接受心肺运动试验的患者由于其他功能限制无法进行最大程度的运动。
对75例慢性心力衰竭患者和12名健康对照者在静息、无氧阈和运动峰值时评估通气/二氧化碳产生比值。根据最大摄氧量判断的心力衰竭严重程度将患者分为两组。
轻中度心力衰竭患者在无氧阈时通气/二氧化碳产生比值降低20%，与健康对照者相似。重度心力衰竭患者在无氧阈时未能降低该比值。此外，早期运动时通气/二氧化碳产生比值降低小于10%预测最大摄氧量<14 ml/kg/min，阳性预测值为96%，阴性预测值为88%。
早期运动时通气/二氧化碳产生比值降低小于10%可可靠地预测充血性心力衰竭患者功能能力较差。在无法进行最大程度运动患者中，该比值在早期运动期间的变化可作为最大摄氧量的替代指标。
