Posturographic Standards for Optimal Control of Human Standing Posture.

Static posturography is a simple non-invasive technique commonly used in contemporary labs and clinics to quantify the central nervous system adaptive mechanisms involved in the control of posture and balance. Its diagnostic value, however, is quite limited due to the lack of posturographic standards for the stable posture. To solve this problem, in this research, we aimed to establish reference values for the stable human posture using our novel parameters of static posturography including the sway anteroposterior directional index (DIAP), the mediolateral directional index (DIML), the stability vector amplitude (SVamp), and the stability vector azimuth (SVaz). Towards this end, in a population of young (mean age 22 yrs), healthy able-bodied volunteers (50 males and 50 females), trajectories of postural sway, based upon the center-of-pressure (COP), were assessed. The experiment consisted of ten 60 s trials that were carried out 5 times while subjects were standing quietly on the force plate with eyes open (EO test) and 5 times with eyes closed (EC test). Results showed that in young healthy subjects, regardless of gender, the basic variables of COP remained at the following levels: SVamp = 9.2 ± 1.6 mm/s, SVaz = 0.9 ± 0.1 rad, and directional indices DIAP = 0.7 ± 0.05, DIML = 0.56 ± 0.06. Some of the measures were sensitive to visual input (EC trials), and showed a weak to moderate correlation with anthropometric features. These measures can be recommended as reference values that characterize the most stable erect posture.

Directional measures of postural sway as predictors of balance instability and accidental falls.

Despite the obvious advantages and popularity of static posturography, universal standards for posturographic tests have not been developed thus far. Most of the center-of-foot pressure (COP) indices are strongly dependent on an individual experimental design, and are susceptible to distortions, which makes results of their analysis incomparable. In this research, we present a novel approach to the analysis of the COP trajectory based on the directional features of postural sway. Our novel output measures: the sway directional indices (DI) and sway vector (SV) were applied to assess the postural stability in the group of young able-bodied subjects. Towards this aim, the COP trajectories were recorded in 100 students standing still for 60 s, with eyes open (EO) and then, with eyes closed (EC). Each record was subdivided then into 20, 30 and 60 s samples. Interclass correlation coefficients were calculated from the samples. The controlled variables (visual conditions) uniquely affected the output measures, but only in case of proper signal pretreatment (low-pass filtering). In filtering below 6 Hz, the DI and SV provided a unique set of descriptors for postural control. Both sway measures were highly independent of the trial length and the sampling frequency, and were unaffected by the sampling noise. Directional indices of COP filtered at 6 Hz showed high to very high reliability, with ICC range of 0.7-0.9. Results of a single 60 s trial are sufficient to reach acceptable reliability for both DI and SV. In conclusion, the directional sway measures may be recommended as the primary standard in static posturography.

Assessment of postural stability in young healthy subjects based on directional features of posturographic data: vision and gender effects.

Directional characteristics of postural sway and their impact on postural stability control (PSC) still need to be clarified. To assess the directional characteristics of PSC, center-of-pressure (COP) while standing quiet was recorded and analyzed in 46 young healthy subjects. The participants completed five 60-s trials with 'eyes open' and five with 'eyes closed'. The control asymmetry was characterized using three standardized COP measures: mean sway velocity (V), sway ratio (SR), and sway directional index (DI). The COP data were low-pass filtered at 10 Hz. In such conditions the V, SR and DI revealed consistent and unique differences in both the anteroposterior (AP) and the mediolateral (ML) controls. Each of the COP measures showed the involvement of different neuromuscular and biomechanical mechanisms in the stabilization of standing posture. The DI documented a very stable proportion between frontal and saggital controls, with roughly 60% of the swaying movements being performed in the AP direction. The AP DI was significantly higher in comparison with the ML value (0.71±0.04 vs. 0.55±0.06). This proportion remained at the same level in both experimental groups and it was only slightly affected by the visual conditions. Analysis of the SR confirmed that to maintain stable stance the neuromuscular system must allocate 50% more effort to control AP stability. The results also documented gender-related differences in postural stability. Generally the female subjects appeared to have lower postural stability as evidenced by higher COM and COP velocities. Consequently the higher SR values observed in the female group indicate a need for higher neuromuscular efforts to maintain stable posture. The introduced here set of COP measures proved to be a valuable standard for static posturography, creating the opportunity for improved and reliable assessment of postural stability.

High dose erythropoietin increases brain tissue oxygen tension in severe vasospasm after subarachnoid hemorrhage.

BACKGROUND: Vasospasm-related delayed cerebral ischemia (DCI) significantly impacts on outcome after aneurysmal subarachnoid hemorrhage (SAH). Erythropoietin (EPO) may reduce the severity of cerebral vasospasm and improve outcome, however, underlying mechanisms are incompletely understood. In this study, the authors aimed to investigate the effect of EPO on cerebral metabolism and brain tissue oxygen tension (PbtO2). METHODS: Seven consecutive poor grade SAH patients with multimodal neuromonitoring (MM) received systemic EPO therapy (30.000 IU per day for 3 consecutive days) for severe cerebral vasospasm. Cerebral perfusion pressure (CPP), mean arterial blood pressure (MAP), intracranial pressure (ICP), PbtO2 and brain metabolic changes were analyzed during the next 24 hours after each dose given. Statistical analysis was performed with a mixed effects model. RESULTS: A total of 22 interventions were analyzed. Median age was 47 years (32-68) and 86 % were female. Three patients (38 %) developed DCI. MAP decreased 2 hours after intervention (P < 0.04) without significantly affecting CPP and ICP. PbtO2 significantly increased over time (P < 0.05) to a maximum of 7 ± 4 mmHg increase 16 hours after infusion. Brain metabolic parameters did not change over time. CONCLUSIONS: EPO increases PbtO2 in poor grade SAH patients with severe cerebral vasospasm. The effect on outcome needs further investigation.

[After care for puerperal women. A literature review]. / Nachbetreuung von Wöchnerinnen. Ein Literaturreview.

BACKGROUND: The length of stay in hospital after child delivery has decreased in almost all western countries over the last decades. It is unclear what the consequences of an early discharge regarding the feelings of women in childbed are and which types of caring after discharge are provided. AIM: To investigate the literature on how early discharge is defined and which are the consequences on young mothers. Particular focus is set on services including relief in household. RESULTS: The term "early discharge" is defined very broadly depending on each country and its health policy. The well-being of women in childbed, mostly influenced by fatigue and postnatal depression, has a frightening prevalence rate. It has been demonstrated that post delivery fatigue is not a short time disturbance of energy level but exhaustion lasting several months. Postnatal depression is rarely measured in women and accordingly, is not treated. All investigated longitudinal studies show that the assumption that physical and mental normality is restored within eight weeks is not true. The decision to discharge was rarely based on scientific knowledge but on economical factors. In the investigated after delivery service models practical services in household are hardly described. Housekeeping seems to be no part of interdisciplinary tasks. CONCLUSION: Satisfaction and self-experience in women after delivery seem to depend on their control of decision making about endurance, frequency and timing of support. Early discharge is increasing and must be accompanied by competent support and advice by well prepared home carers.