Mak V H, Bugler J R, Spiro S G
Department of Thoracic Medicine, University College Hospital, London.
Thorax. 1993 Oct;48(10):979-84. doi: 10.1136/thx.48.10.979.
Long term oral corticosteroid treatment is a cause of myopathy of the skeletal muscles. The effect of long term treatment with oral corticosteroids on the respiratory muscles is uncertain. Respiratory muscle function and fatigue in sternomastoid muscle were investigated in a group of patients with chronic severe asthma who were taking oral corticosteroids. The results were compared with those from a group of patients with chronic airflow limitation who were not taking oral steroids.
Twelve patients with chronic severe asthma, taking a mean daily dosage of 8 mg of prednisolone for a mean (SD) of 16.8 (9.1) years, were compared with patients with chronic airflow limitation and individually matched for sex, age, and severity of airflow limitation. Lung function tests, maximal mouth pressures, and quadriceps and sternomastoid muscle strength were measured. The sternomastoid muscle was fatigued by maximal headlift exercise to 70% of initial headlift force and the endurance time noted. Sternomastoid fatigue was assessed by twitch maximum relaxation rate (TMRR) measured in the fresh state and for 30 minutes after exercise.
There was no significant difference between the control group and the corticosteroid group for maximal mouth pressures, fresh state TMRR, and quadriceps and sternomastoid strength. The control group had a significantly longer mean (SD) endurance time than the corticosteroid group (121 (47) s v 86 (24) s), and also had significantly less slowing and faster recovery of the TMRR after exercise. The slowing and recovery of the TMRR in the corticosteroid group, however, was similar to that previously reported for normal subjects.
Respiratory muscle weakness does not occur more often in patients taking oral corticosteroids. The corticosteroid group was more prone to fatigue than the control group, but was similar to normal subjects. This suggests that chronic airflow limitation may produce a training effect on the respiratory muscles that might be attenuated by long term oral corticosteroid treatment.
长期口服皮质类固醇治疗是骨骼肌肌病的一个病因。长期口服皮质类固醇对呼吸肌的影响尚不确定。我们对一组正在服用口服皮质类固醇的慢性重度哮喘患者的呼吸肌功能及胸锁乳突肌疲劳情况进行了研究，并将结果与一组未服用口服类固醇的慢性气流受限患者进行比较。
选取12例慢性重度哮喘患者，他们平均每日服用8毫克泼尼松龙，平均（标准差）服药16.8（9.1）年，将其与慢性气流受限患者进行比较，这些患者在性别、年龄及气流受限严重程度方面进行了个体匹配。测量了肺功能、最大口腔压力、股四头肌及胸锁乳突肌力量。通过最大抬头运动使胸锁乳突肌疲劳至初始抬头力的70%，并记录耐力时间。通过在新鲜状态及运动后30分钟测量的抽搐最大松弛率（TMRR）评估胸锁乳突肌疲劳情况。
对照组与皮质类固醇组在最大口腔压力、新鲜状态TMRR、股四头肌及胸锁乳突肌力量方面无显著差异。对照组的平均（标准差）耐力时间显著长于皮质类固醇组（121（47）秒对86（24）秒），且运动后TMRR的减慢及恢复也显著较少。然而，皮质类固醇组TMRR的减慢及恢复与先前报道的正常受试者相似。
服用口服皮质类固醇的患者呼吸肌无力并不更常见。皮质类固醇组比对照组更容易疲劳，但与正常受试者相似。这表明慢性气流受限可能对呼吸肌产生一种训练效应，而长期口服皮质类固醇治疗可能会减弱这种效应。
