College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom.
Am J Kidney Dis. 2012 Dec;60(6):930-9. doi: 10.1053/j.ajkd.2012.06.021. Epub 2012 Aug 9.
Fatigue is one of the most prevalent symptoms in chronic kidney disease (CKD). However, fatigue mechanisms are poorly understood due in part to nonspecific definitions. This study investigates exertional fatigue during simulated activities of daily living, focusing on oxygen delivery and utilization.
"Explanatory" matched-cohort study.
PARTICIPANTS & SETTING: 13 patients with CKD (stages 3b-4; mean age, 62 ± 13 [SD] years) and 13 healthy controls, mean matched for age, height, body mass and composition, and physical activity level. Participants completed an incremental cycle ergometer test to simulate energy expenditure of typical activities of daily living.
4 exercise intensities: 1, 1.8, 2.4, and 3.1 metabolic equivalent tasks (METs).
The primary outcome was exertional fatigue by rating of perceived exertion (RPE) on a 6-20 scale.
Other multidimensional measures of fatigue: UK Short Form Health Survey 36 (UK SF-36) Vitality and Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) subscales. Physiologic measures of the oxygen transport and utilization chain (expired gas analysis, cardiac output, and arterial oxygen content) and blood lactate.
RPE was increased in patients compared with controls at 2.4 (10.5 [ie, light] ± 2.7 vs 8.7 [very light] ± 1.7 units) and 3.1 (12.5 [somewhat hard] ± 2.6 vs 10.2 [light] ± 1.7 units) METs (interaction P = 0.03), which was consistent with higher chronic fatigue in patients by both the UK SF-36 Vitality (P = 0.01) and FACIT-Fatigue (P = 0.004) subscales. Arterial oxygen content was decreased in patients (P = 0.001), but cardiac output and oxygen extraction ratio were unchanged, decreasing oxygen delivery (P = 0.04). Respiratory exchange ratio (P = 0.004) and blood lactate production (P = 0.002) were increased.
Those inherent to a matched-cohort study.
Using a novel application of the outcome measure RPE, patients with non-dialysis-dependent CKD reported considerable exertional fatigue during simulated activities of daily living. Poor compensation for mild anemia contributed to this symptom. In addition to anemia, the entire oxygen transport chain needs to be targeted to treat fatigue in patients with CKD.
疲劳是慢性肾脏病（CKD）最常见的症状之一。然而，由于定义不明确，疲劳机制仍不清楚。本研究旨在通过模拟日常活动来研究运动性疲劳，重点关注氧的输送和利用。
“解释性”匹配队列研究。
13 名 CKD 患者（3b-4 期；平均年龄 62±13[SD]岁）和 13 名健康对照者，平均年龄、身高、体重和成分以及体力活动水平相匹配。参与者完成递增式踏车测力计测试，以模拟日常活动的能量消耗。
4 种运动强度：1、1.8、2.4 和 3.1 代谢当量任务（METs）。
主要结果是通过 6-20 级评分量表感知疲劳（RPE）来评估的运动性疲劳。
英国简短健康调查 36 项（UK SF-36）活力和慢性疾病治疗疲劳评估量表-疲劳（FACIT-Fatigue）子量表。氧转运和利用链的生理测量（呼出气体分析、心输出量和动脉血氧含量）和血乳酸。
与对照组相比，患者在 2.4（10.5[即轻度]±2.7 与 8.7[非常轻度]±1.7 单位）和 3.1（12.5[有点困难]±2.6 与 10.2[轻度]±1.7 单位）METs 时 RPE 增加（交互 P=0.03），这与患者 UK SF-36 活力（P=0.01）和 FACIT-Fatigue（P=0.004）子量表中更高的慢性疲劳一致。患者的动脉血氧含量降低（P=0.001），但心输出量和氧摄取率不变，导致氧输送减少（P=0.04）。呼吸交换率（P=0.004）和血乳酸生成（P=0.002）增加。
匹配队列研究固有的局限性。
使用 RPE 这一新型结局测量方法，非透析依赖性 CKD 患者在模拟日常活动中报告了相当大的运动性疲劳。轻度贫血的补偿不足导致了这种症状。除了贫血，整个氧输送链都需要被靶向以治疗 CKD 患者的疲劳。
