Forte S, Carlone S, Vaccaro F, Onorati P, Manfredi F, Serra P, Palange P
Dipartimento di Medicina Clinica, University of Rome La Sapienza, Italy.
J Rheumatol. 1999 Dec;26(12):2591-4.
Exercise tolerance is often reduced in patients with systemic lupus erythematosus (SLE). Mechanisms have been proposed but the underlying causes have not yet been elucidated. The study of pulmonary gas exchange during exercise may be helpful in revealing circulatory, ventilatory, and metabolic abnormalities. We hypothesized that in SLE, exercise aerobic capacity would be reduced due to chronic inactivity and poor muscle energetics.
Thirteen women with SLE and low disease activity were studied; 5 age matched subjects served as controls. Clinical examination, chest radiography, electrocardiogram, and pulmonary function test were all normal. Subjects underwent 1 min incremental cycle ergometer exercise to exhaustion. Oxygen uptake (VO2), CO2 output (VCO2), minute ventilation (VE), heart rate (HR), and arterial O2 saturation were monitored. Anaerobic threshold (AT), VO2/HR, deltaVO2/deltaWatt, respiratory rate (RR), Ti/Ttot, VE/VCO2, and breathing reserve (BR) were computed.
At rest, patients exhibited high VE, respiratory alkalosis, and a wide alveolar-arterial O2 gradient [(A - a)O2] during 50% O2 breathing. Other indexes of respiratory function were within the normal range. In the 6 patients with SLE where pulmonary artery systolic pressure at Doppler echocardiography was measurable, mean level was in the upper limits of normal. During exercise, maximal aerobic capacity was reduced in all patients (VO2 peak, 1098+/-74 vs. 2150+/-160 ml/min, p<0.01; AT, 36 +/-3 vs. 48+/-3% predicted VO2 max, p<0.05). Ventilation adjusted for the metabolic demand (VE/VCO2 at AT) was increased (31+/-1 vs. 24+/-1; p<0.05). A normal breathing pattern was observed during all tests. No patient stopped exercising because of ventilatory limitation (i.e., they had normal breathing reserve).
Reduced muscle aerobic capacity is common in SLE and is most likely because of peripheral muscle deconditioning. Increased ventilatory demand, secondary to diffuse interstitial lung disease, is not a significant contributor to the reduction in exercise tolerance.
系统性红斑狼疮（SLE）患者的运动耐力常降低。虽已提出多种机制，但潜在病因尚未阐明。研究运动期间的肺气体交换可能有助于揭示循环、通气和代谢异常。我们推测，在SLE患者中，运动有氧能力降低是由于长期不活动和肌肉能量代谢不佳所致。
对13名疾病活动度低的SLE女性患者进行了研究；5名年龄匹配的受试者作为对照。临床检查、胸部X线摄影、心电图和肺功能测试均正常。受试者进行1分钟递增式蹬车运动直至力竭。监测摄氧量（VO2）、二氧化碳排出量（VCO2）、分钟通气量（VE）、心率（HR）和动脉血氧饱和度。计算无氧阈（AT）、VO2/HR、deltaVO2/deltaWatt、呼吸频率（RR）、吸气时间/总呼吸时间（Ti/Ttot）、VE/VCO2和呼吸储备（BR）。
静息时，患者在吸入50%氧气时表现出高VE、呼吸性碱中毒和较宽的肺泡 - 动脉氧梯度[（A - a）O2]。呼吸功能的其他指标在正常范围内。在6名可通过多普勒超声心动图测量肺动脉收缩压的SLE患者中，平均水平在正常上限。运动期间，所有患者的最大有氧能力均降低（VO2峰值，1098±74 vs. 2150±160 ml/分钟，p<0.01；AT，36±3 vs. 48±3%预计VO2最大值，p<0.05）。根据代谢需求调整的通气（AT时的VE/VCO2）增加（31±1 vs. 24±1；p<0.05）。所有测试期间均观察到正常呼吸模式。没有患者因通气受限而停止运动（即他们的呼吸储备正常）。
肌肉有氧能力降低在SLE中很常见，最可能是由于外周肌肉失健。继发于弥漫性间质性肺病的通气需求增加并非运动耐力降低的重要原因。
