Mancini D M, Henson D, LaManca J, Levine S
Cardiovascular Section, Veterans Administration Medical Center, Philadelphia, Pennsylvania.
J Am Coll Cardiol. 1994 Oct;24(4):972-81. doi: 10.1016/0735-1097(94)90858-3.
We sought to investigate whether reduced respiratory muscle endurance contributes to increased dyspnea and decreased exercise capacity in patients with chronic heart failure.
In patients with heart failure, the sensation of dyspnea may be related to abnormalities of respiratory muscle function, such as diminished strength or endurance, or both.
Respiratory muscle endurance was assessed by measuring maximal sustainable ventilatory capacity in 15 patients with congestive heart failure and 8 normal subjects using progressive isocapnic hyperpnea. Near-infrared spectroscopy of an accessory respiratory muscle, Borg scale recordings of perceived dyspnea, time in inspiration, time per breath and minute ventilation were measured. Exercise testing with measurement of oxygen consumption was also performed.
Maximal voluntary ventilation (normal subjects 167 +/- 40, heart failure group 89 +/- 31 liters/min) and maximal sustainable ventilatory capacity (normal subjects 90 +/- 23, heart failure group 53 +/- 22 liters/min) were significantly reduced in patients with heart failure (both p < 0.05). No significant accessory respiratory muscle deoxygenation was observed in either group. Borg scale recordings at maximal sustainable ventilatory capacity were comparable in both groups. At rest, the inspiratory duty cycle (i.e., time in inspiration divided by the time per breath) was comparable in the two groups (normal subjects 0.34 +/- 0.09, heart failure group 0.37 +/- 0.12, p = NS). However at maximal sustainable ventilatory capacity, only normal subjects had a significant increase in the inspiratory duty cycle (normal subjects 0.49 +/- 0.04, heart failure group 0.36 +/- 0.10, p < 0.05). This finding suggests obstruction to airflow in patients with congestive heart failure. Values for peak exercise minute ventilation did not differ significantly from values in maximal sustainable ventilatory capacity in either group and were significantly correlated (r = 0.84, p < 0.0001).
Respiratory muscle endurance as assessed by maximal sustainable ventilatory capacity is reduced in patients with heart failure.
我们试图研究呼吸肌耐力下降是否会导致慢性心力衰竭患者呼吸困难加重和运动能力降低。
在心力衰竭患者中，呼吸困难的感觉可能与呼吸肌功能异常有关，如力量减弱或耐力下降，或两者皆有。
通过使用渐进性等碳酸过度通气法测量15例充血性心力衰竭患者和8例正常受试者的最大可持续通气能力来评估呼吸肌耐力。测量辅助呼吸肌的近红外光谱、主观呼吸困难的Borg量表记录、吸气时间、每次呼吸时间和分钟通气量。还进行了测量耗氧量的运动测试。
心力衰竭患者的最大自主通气量（正常受试者167±40，心力衰竭组89±31升/分钟）和最大可持续通气能力（正常受试者90±23，心力衰竭组53±22升/分钟）均显著降低（均p<0.05）。两组均未观察到明显的辅助呼吸肌脱氧现象。两组在最大可持续通气能力时的Borg量表记录相当。静息时，两组的吸气占比（即吸气时间除以每次呼吸时间）相当（正常受试者0.34±0.09，心力衰竭组0.37±0.12，p=无统计学意义）。然而，在最大可持续通气能力时，只有正常受试者的吸气占比显著增加（正常受试者0.49±0.04，心力衰竭组0.36±0.10，p<0.05）。这一发现提示充血性心力衰竭患者存在气流阻塞。两组的运动峰值分钟通气量与最大可持续通气能力的值无显著差异，且显著相关（r=0.84，p<0.0001）。
通过最大可持续通气能力评估的心力衰竭患者呼吸肌耐力降低。
