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Abstract Background Falls are a significant public health problem. Thirty to fifty percent of the elderly of 65 years and older fall each year. Falls are the most common type of accident in this age group and can result in fractures and subsequent disabilities, increased fear of falling, social isolation, decreased mobility, and even an increased mortality. Several forms of exercise have been associated with a reduced risk of falling and with a wide range of physiological as well as psychosocial health benefits. Tai Chi Chuan seems to be the most promising form of exercise in the elderly, but the evidence is still controversial. In this article the design of a randomized clinical trial is presented. The trial evaluates the effect of Tai Chi Chuan on fall prevention and physical and psychological function in older adults. Methods/Design 270 people of seventy years and older living at home will be identified in the files of the participating general practitioners. People will be asked to participate when meeting the following inclusion criteria: have experienced a fall in the preceding year or suffer from two of the following risk factors: disturbed balance, mobility problems, dizziness, or the use of benzodiazepines or diuretics. People will be randomly allocated to either the Tai Chi Chuan group (13 weeks, twice a week) or the no treatment control group. The primary outcome measure is the number of new falls, measured with a diary. The secondary outcome measures are balance, fear of falling, blood pressure, heart rate, lung function parameters, physical activity, functional status, quality of life, mental health, use of walking devices, medication, use of health care services, adjustments to the house, severity of fall incidents and subsequent injuries. Process parameters will be measured to evaluate the Tai Chi Chuan intervention. A cost-effectiveness analysis will be carried out alongside the evaluation of the clinical results. Follow-up measurements will be collected at 3, 6 and 12 months after randomization. Discussion As far as we know this is the first trial in Europe considering Tai Chi Chuan and fall prevention. This project will answer a pragmatic research question regarding the efficacy of Tai Chi Chuan regarding fall reduction.

The results of a randomized clinical trial (RCT) on the effects of a Tai Chi fall prevention in community-living older people with a high risk of falling in the Netherlands showed no beneficial effects on falls and secondary outcomes (e.g., balance, fear of falling). The aim of this study is to provide insight in process-related factors that may have influenced the effectiveness of the intervention. The intervention consisted of Tai Chi Chuan (TCC) training for 1 h twice a week for 13 weeks. We used self-administered questionnaires and registration forms to collect data from participants and instructors. We analyzed quantitative data by means of descriptive statistics and categorized qualitative data based on the content of the answers given. Of the participants, that started the program 89 (79%) completed the intervention, but a minority of 47% attended 80% of more of the lessons. All participants and instructors were positive about the program and most participants reported benefits from the intervention. Suggestions for improvements mainly relate to adjustments of training aspects. The main process-related factors that may be have influenced the lack of beneficial effects on falls and secondary outcomes are the relatively high withdrawal and the low adherence rates., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

Objectives: To evaluate the effectiveness of Tai Chi Chuan in fall prevention in elderly people living at home with a high risk of falling., Design: Randomized controlled trial., Setting: Two industrial towns in the western part of the Netherlands., Participants: Two hundred sixty-nine elderly people (average age 77) living at home with a high risk of falling., Interventions: The intervention group received Tai Chi Chuan training for 1 hour twice a week for 13 weeks; the control group received usual care. Both groups received a brochure containing general information on how to prevent fall incidents., Measurements: Primary outcome was the number of falls over 12 months. Secondary outcomes were balance, fear of falling, blood pressure, heart rate at rest, forced expiratory volume during the first second, peak expiratory flow, physical activity, and functional status., Results: After 12 months, no lower fall risk in the Tai Chi Chuan group was observed than in the control group (adjusted hazard ratio=1.16; 95% confidence interval=0.84-1.60), and there were no significant intervention effects on the secondary outcome measures., Conclusion: These results suggest that Tai Chi Chuan may not be effective in elderly people at a high risk of falling who live at home.

Objective: To study the effect of cardiac contraction on left coronary artery pressure-flow relations at different vascular volumes and to compare these relations in the beating heart with those in the heart arrested in systole and diastole., Methods: Maximally vasodilated, Tyrode perfused, rabbit hearts (n = 6) with an intra-ventricular balloon were used. The left coronary artery was separately perfused via a cannula in the left main coronary artery. The slopes and the intercepts of left coronary pressure-flow relations were determined in the beating and arrested heart at different chamber volumes. A 3-factor design with repeated measures was used to compare the effect of three factors: phase of contraction (systole and diastole), chamber volume (V0 and V1, left ventricular end-diastolic pressure 1.4 and 20 mm Hg, respectively) and the type of contraction (beating and arrested; a measure of capacitive effects)., Results: The phase of contraction has a significant effect on the intercepts (> 40 mmHg, p = 0.00032) but not on the slopes of the pressure-flow relations. Chamber volume had a small effect on the intercepts (< 5 mm Hg, p = 0.037), but not on the slopes of the pressure-flow relations. The type of contraction has a significant effect on the slopes (approximately 10%, p = 0.00021) but not on the intercepts of the pressure-flow relations., Conclusions: In the isolated Tyrode perfused rabbit heart left coronary pressure-flow relations are mainly determined by contraction, while left ventricular chamber volume and capacitive effects contribute little.

Delay in development after open-heart surgery in infants has frequently been reported. Inadequate brain perfusion and oxygenation during deep hypothermic cardiopulmonary bypass (CPB) may play an important role. We investigated the effect of CPB on cerebral perfusion and oxygenation in 12 neonates and infants (age 0-11 months) undergoing open-heart surgery. Changes in cerebral blood volume (delta CBV; in ml/100 g brain tissue) and oxidation level of the intracerebral mitochondrial enzyme cytochrome aa3 (delta Cytaa3; in mumol/l) were measured with near infrared spectroscopy. Nasopharyngeal temperature (Tnas) for assessment of changes in brain temperature, and mean arterial blood pressure (MAP) were monitored continuously. CBV lowered during cooling and increased during rewarming. These changes were only related with changes in Tnas (p < 0.001; 0.07 ml.100 g-1/ degrees C). No relation was found with changes in MAP or pump flow rate of the heart-lung machine. During steady-state hypothermic CPB, changes in CBV were only related to changes in MAP (p < 0.001). The individual regression lines between delta CBV and MAP became steeper at lower absolute Tnas. Cytaa3 showed an increase shortly after the initiation of CPB in 9 patients, with a sustained decrease to baseline values in 8 patients towards the end of the CPB period. Two patients who had a circulatory arrest during CPB had a sharp decrease in delta cytaa3 after cessation of the heart-lung pump and showed no complete recovery of delta Cytaa3 to baseline at the end of the CPB period. We conclude that changes in CBV during CPB are related to changes in Tnas. During deep hypothermic steady-state CPB, changes in CBV and MAP were related to each other, suggesting lack of cerebral autoregulation. The large decrease in Cytaa3 in 2 patients with circulatory arrest suggests that this procedure compromises energy metabolism of the brain cell.

Objective: To investigate whether or not postasphyctic cerebral hypoperfusion and decreased cerebral metabolism occur in the perinatally asphyxiated neonate, as has been reported in adults and newborn animals., Methods: Using near-infrared spectroscopy, we monitored changes in oxyhemoglobin (HbO2), deoxyhemoglobin (HbR), total hemoglobin (HbO2 + HbR, which represents changes in cerebral blood volume [CBV]), and cytochrome oxidase (Cytaa3, which indicates changes in oxidation level of this intracerebral mitochondrial enzyme). Thirty-one neonates (gestational age > 34 weeks), divided into three groups, were monitored between 2 and 12 hours or between 12 and 24 hours of life. Group I consisted of healthy newborns: N = 8 (2 to 12 hours) and N = 5 (12 to 24 hours). Patients in group II were moderately asphyxiated newborns but neurologically normal in the first 24 hours of life: N = 6 (2 to 12 hours) and N = 3 (12 to 24 hours). Group III consisted of severely asphyxiated newborns with an abnormal neurologic behavior within 24 hours after birth: N = 5 (2 to 12 hours) and N = 4 (12 to 24 hours)., Results: From 2 to 12 h, CBV levels in groups I and II were stable. In group III CBV decreased in all infants. This decrease in CBV was associated with a drop in both HbO2 and HbR. Cytaa3 was stable in groups I and II, but showed a marked decrease in two of the five infants of group III. There was a positive relationship between CBV and mean arterial blood pressure in groups II and III. Between 12 and 24 hours, all groups showed stable CBV and Cytaa3 patterns. A positive relation existed now between transcutaneous PCO2 and CBV in groups II and III., Conclusions: CBV, HbO2, HbR, and Cytaa3 decreased in the first 12 hours of life in severely asphyxiated neonates who subsequently developed neurologic abnormalities. We therefore suggest that posthypoxic-ischemic reperfusion injury of the brain during early neonatal life occurs in neonates with severe birth asphyxia.