Is the impact of fatigue related to walking capacity and perceived ability in persons with multiple sclerosis? A multicenter study.

BACKGROUND: The relationship between fatigue impact and walking capacity and perceived ability in patients with multiple sclerosis (MS) is inconclusive in the existing literature. A better understanding might guide new treatment avenues for fatigue and/or walking capacity in patients with MS. OBJECTIVE: To investigate the relationship between the subjective impact of fatigue and objective walking capacity as well as subjective walking ability in MS patients. METHODS: A cross-sectional multicenter study design was applied. Ambulatory MS patients (n = 189, age: 47.6 ±â€¯10.5 years; gender: 115/74 women/men; Expanded Disability Status Scale (EDSS): 4.1 ±â€¯1.8 [range: 0-6.5]) were tested at 11 sites. Objective tests of walking capacity included short walking tests (Timed 25-Foot Walk (T25FW), 10-Metre Walk Test (10mWT) at usual and fastest speed and the timed up and go (TUG)), and long walking tests (2- and 6-Minute Walk Tests (MWT). Subjective walking ability was tested applying the Multiple Sclerosis Walking Scale-12 (MSWS-12). Fatigue impact was measured by the self-reported modified fatigue impact scale (MFIS) consisting of a total score (MFIStotal) and three subscales (MFISphysical, MFIScognitive and MFISpsychosocial). Uni- and multivariate regression analysis were performed to evaluate the relation between walking and fatigue impact. RESULTS: MFIStotal was negatively related with long (6MWT, r = -0.14, p = 0.05) and short composite (TUG, r = -0.22, p = 0.003) walking measures. MFISphysical showed a significant albeit weak relationship to walking speed in all walking capacity tests (r = -0.22 to -0.33, p < .0001), which persisted in the multivariate linear regression analysis. Subjective walking ability (MSWS-12) was related to MFIStotal (r = 0.49, p < 0.0001), as well as to all other subscales of MFIS (r = 0.24-0.63, p < 0.001), showing stronger relationships than objective measures of walking. CONCLUSIONS: The physical impact of fatigue is weakly related to objective walking capacity, while general, physical, cognitive and psychosocial fatigue impact are weakly to moderately related to subjective walking ability, when analysed in a large heterogeneous sample of MS patients.

Effect of time of day on walking capacity and self-reported fatigue in persons with multiple sclerosis: a multi-center trial.

BACKGROUND: Many persons with multiple sclerosis (PwMS) report increased fatigue in the afternoon and evening compared with the morning. It is commonly accepted that physical capacity also decreases as time of day progresses, potentially influencing the outcomes of testing. OBJECTIVE: The objective of this article was to determine whether self-reported fatigue level and walking capacity are influenced by time of day in PwMS. METHODS: A total of 102 PwMS from 8 centers in 5 countries, with a diverse level of ambulatory dysfunction (Expanded Disability Status Scale [EDSS] <6.5), participated. Patients performed walking capacity tests and reported fatigue level at three different time points (morning, noon, afternoon) during 1 day. Walking capacity was measured with the 6-Minute Walk Test (6MWT) and the 10-m walk test performed at usual and fastest speed. Self-reported fatigue was measured by the Rochester Fatigue Diary (RFD). Subgroups with mild (EDSS 1.5-4.0, n = 53) and moderate (EDSS 4.5-6.5, n = 49) ambulatory dysfunction were formed, as changes during the day were hypothesized to depend on disability status. RESULTS: Subgroups had different degree of ambulatory dysfunction (p < 0.001) but reported similar fatigue levels. Although RFD scores were affected by time of day with significant differences between morning and noon/afternoon (p < 0.0001), no changes in walking capacity were found in any subgroup. Additional analyses on subgroups distinguished by diurnal change in self-reported fatigue failed to reveal analogous changes in walking capacity. CONCLUSIONS: Testing of walking capacity is unaffected by time of day, despite changes in subjective fatigue.

Oxygen consumption, energy expenditure, and substrate utilization after cardiac surgery in children.

OBJECTIVE: To determine the oxygen consumption (VO2), resting energy expenditure, and substrate utilization after cardiac surgery in children. DESIGN: Prospective, observational, cross-sectional study with factorial design. SETTING: Pediatric ICU at a university hospital. PATIENTS: Twenty-six consecutive children during the first 3 days after open-heart surgery. INTERVENTIONS: Patients were mechanically ventilated and received routine therapeutic interventions. MEASUREMENTS AND MAIN RESULTS: VO2, resting energy expenditure, and substrate utilization were determined by indirect calorimetry. Cardiac index was calculated using the Fick equation from the measured VO2 and the arterial-mixed venous oxygen content difference, and this cardiac index value was compared with a simultaneous cardiac index value that was measured by thermodilution whenever possible. There were excellent correlation and agreement between cardiac index measurements by Fick equation and thermodilution, indicating accurate VO2 measurements. VO2 was consistent with predicted values in healthy resting children. Resting energy expenditure was consistent with the predicted basal metabolic rate. The mean caloric intake was 19% of the mean energy expenditure. The respiratory quotient was 0.74 +/- 0.05. The substrate utilization showed a shift toward fat oxidation and either gluconeogenesis or impaired carbohydrate utilization. CONCLUSIONS: Cardiovascular surgery in children does not significantly alter resting energy expenditure but influences the substrate utilization. Perioperative hormonal stress responses and therapeutically administered catecholamines may explain the shift toward fat oxidation.