McParland C, Krishnan B, Wang Y, Gallagher C G
Department of Medicine, University of Saskatchewan, Saskatoon, Canada.
Am Rev Respir Dis. 1992 Aug;146(2):467-72. doi: 10.1164/ajrccm/146.2.467.
Dyspnea is a common, disabling symptom in chronic heart failure, yet the underlying mechanisms remain unknown. The respiratory muscle pump is composed of skeletal muscles whose strength directly influences the pump's performance. Respiratory muscle weakness is important in the dyspnea experienced by some patients with pulmonary disease; however, the role of the respiratory muscle pump in the dyspnea of chronic heart failure has not previously been examined. To assess respiratory muscle strength and its relation to dyspnea during daily activity, we measured maximum inspiratory and expiratory mouth pressures as indices of respiratory muscle strength and the baseline dyspnea index in nine stable, chronic cardiac pump failure patients who had no evidence of primary lung disease, and in nine age- and sex-matched healthy control subjects. The chronic heart failure patients, when compared with their matched control subjects, had reduced inspiratory and expiratory muscle strength, and both inspiratory and expiratory muscle strength were significantly correlated with dyspnea during daily activity (r2 = 0.80, p = 0.001 and r2 = 0.45, p = 0.05, respectively). Inspiratory muscle strength accounted for all of the variance in dyspnea that was correlated with respiratory muscle strength when the relative contributions of inspiratory and expiratory muscle strength were examined. There was no correlation between lung volumes or spirometry and dyspnea in the heart failure patients. These findings indicate that patients with stable chronic heart failure have inspiratory and expiratory muscle weakness and further suggest that the respiratory muscle pump significantly contributes to the dyspnea during the activities of daily living.
呼吸困难是慢性心力衰竭中常见的、导致功能障碍的症状，但其潜在机制仍不清楚。呼吸肌泵由骨骼肌组成，其力量直接影响泵的性能。呼吸肌无力在一些肺部疾病患者所经历的呼吸困难中起重要作用；然而，呼吸肌泵在慢性心力衰竭所致呼吸困难中的作用此前尚未得到研究。为了评估日常活动期间呼吸肌力量及其与呼吸困难的关系，我们测量了9名稳定的慢性心脏泵衰竭患者（无原发性肺部疾病证据）和9名年龄及性别匹配的健康对照者的最大吸气和呼气口腔压力，以此作为呼吸肌力量的指标以及基线呼吸困难指数。与匹配的对照者相比，慢性心力衰竭患者的吸气和呼气肌力量降低，并且吸气和呼气肌力量均与日常活动期间的呼吸困难显著相关（分别为r2 = 0.80，p = 0.001和r2 = 0.45，p = 0.05）。当检查吸气和呼气肌力量的相对贡献时，吸气肌力量解释了与呼吸肌力量相关的呼吸困难的所有方差。心力衰竭患者的肺容积或肺量测定与呼吸困难之间无相关性。这些发现表明，稳定的慢性心力衰竭患者存在吸气和呼气肌无力，并进一步提示呼吸肌泵在日常生活活动期间的呼吸困难中起显著作用。
