A meta-analysis of vascular access outcomes in hemodialysis patients aged 75 years or older.

BACKGROUND: Several existing guidelines advocate the access creation without any specific recommendations for those patients over 75 years of age. The aim of this meta-analysis is to compare the outcomes of different vascular access procedures in the sub-group of elderly ESRD patients ⩾75 years of age. METHODS: A literature search was performed using the MEDLINE and SCOPUS electronic databases. The analysis focused on studies with subgroups of elderly patients ⩾75 years of age with different vascular access procedures, and compared the failure rates of autologous versus prosthetic vascular access. Articles comparing patency rates of distal (forearm) versus proximal upper arm AVFs were also investigated. RESULTS: Twelve relevant studies were identified and included in the meta-analysis. The pooled results revealed a statistically significant unassisted (primary) failure rate at 24 months in favor of autologous AVFs [odds ratio (OR): 0.56, 95% CI: 0.38-0.83, p = 0.003]. A secondary analysis revealed significantly higher 12 months unassisted (primary) and secondary failure rates of forearm AVFs compared with proximal upper arm AVFs (OR: 2.14, 95% CI: 1.53-2.97, p < 0.00001 and OR: 1.76, 95% CI: 1.12-2.78, p < 0.01 respectively). CONCLUSION: An increased risk of failure of prosthetic vascular access procedures was found compared with autologous AVFs in patients ⩾75 years of age. Elderly patients ⩾75 years should not be excluded from creation of an autologous access, with proximal upper arm AVFs having better patency rates.

Electroencephalogram reactivity to verbal command after dexmedetomidine, propofol and sevoflurane-induced unresponsiveness.

Although electroencephalogram reactivity (i.e. transient changes in electrical brain activity following external stimulus) might be useful in depth-of-anaesthesia monitoring, it has not been systematically examined with different anaesthetics at doses titrated to unresponsiveness. Three 10-subject groups of healthy volunteers received dexmedetomidine, propofol or sevoflurane in escalating pseudo-steady-state concentrations at 10-min intervals until they did not open their eyes to command. The electroencephalogram was continuously recorded and spectral variables were calculated with short-time Fourier transform and time-varying autoregressive modelling. Electroencephalogram reactivity was most prominent in the midfrontal derivations (termed F3 and F4). During drug-induced unresponsiveness, electroencephalogram reactivity was still present in all drug groups. Dexmedetomidine, propofol and sevoflurane induced distinct suppression patterns on the electroencephalogram reactivity at the same clinical endpoint (unresponsiveness). Reactivity was best maintained with propofol, while only minimally preserved with dexmedetomidine and sevoflurane. Thus, it may be difficult to harness reactivity for depth-of-anaesthesia monitoring.

Umbilical cord length in singleton gestations: a Finnish population-based retrospective register study.

INTRODUCTION: Many complications of pregnancy and delivery are associated with umbilical cord length. It is important to examine the variation in length, in order to identify normal and abnormal conditions. Moreover, the factors influencing cord growth and development are not precisely known. OBJECTIVE: The main objectives were to provide updated reference charts for umbilical cord length in singleton pregnancies and to evaluate potential factors affecting cord length. METHODS: Birth register data of 47,284 singleton pregnant women delivering in Kuopio University Hospital, Finland was collected prospectively. Gender-specific centile charts for cord length from 22 to 44 gestational weeks were obtained using generalized additive models for location, scale, and shape (GAMLSS). Gestational, fetal, and maternal factors were studied for their potential influence on cord length with single variable analysis and stepwise multiple linear regression analysis. RESULTS: Cord length increased according to gestational age, while the growth decelerated post-term. Birth weight, placental weight, pregravid maternal body mass index, parity, and maternal age correlated to cord length. Gestational diabetes and previous miscarriages were associated with longer cords, while female gender and placental abruption were associated with shorter cords. DISCUSSION AND CONCLUSIONS: Girls had shorter cords throughout gestation although there was substantial variation in length in both genders. Cord length associated significantly with birth weight, placental weight, and gestational age. Significantly shorter cords were found in women with placental abruption. This important finding requires further investigation.

Linear and nonlinear tremor acceleration characteristics in patients with Parkinson's disease.

The purpose of the study was to evaluate linear and nonlinear tremor characteristics of the hand in patients with Parkinson's disease (PD) and to compare the results with those of healthy old and young control subjects. Furthermore, the aim was to study correlation between tremor characteristics and clinical signs. A variety of nonlinear (sample entropy, cross-sample entropy, recurrence rate, determinism and correlation dimension) and linear (amplitude, spectral peak frequency and total power, and coherence) hand tremor parameters were computed from acceleration measurements for PD patients (n = 30, 68.3 ± 7.8 years), and old (n = 20, 64.2 ± 7.0 years) and young (n = 20, 18.4 ± 1.1 years) control subjects. Nonlinear tremor parameters such as determinism, sample entropy and cross-sample entropy were significantly different between the PD patients and healthy controls. These parameters correlated with the Unified Parkinson's disease rating scale (UPDRS), tremor and finger tapping scores, but not with the rigidity scores. Linear tremor parameters such as the amplitude and the maximum power (power corresponding to peak frequency) also correlated with the clinical findings. No major difference was detected in the tremor characteristics between old and young control subjects. The study revealed that tremor in PD patients is more deterministic and regular when compared to old or young healthy controls. The nonlinear tremor parameters can differentiate patients with PD from healthy control subjects and these parameters may have potential in the assessment of the severity of PD (UPDRS).

Analysis of heart rate variability dynamics during propofol and dexmedetomidine anesthesia.

It has been observed that heart rate variability (HRV) diminishes during anesthesia, but the exact mechanisms causing it are not completely understood. The aim of this paper was to study the dynamics of HRV during low dose propofol (N=9) and dexmedetomidine (N=8) anesthesia by using state-of-the-art time-varying methods, and thereby ultimately try to improve the safety of anesthesia. The time-varying spectrum is estimated by using a Kalman smoother approach. The results show that there is an overall increase in HRV and decrease in heart rate prior to loss of consciousness. For dexmedetomidine these changes are more considerable than for propofol. For dexmedetomidine the variability also seems to start decreasing right after loss of consciousness, whereas for propofol HRV continues increasing.

Decommissioning a phosphoric acid production plant: a radiological protection case study.

During a preliminary survey at the area of an abandoned fertilizer plant, increased levels of radioactivity were measured at places, buildings, constructions and materials. The extent of the contamination was determined and the affected areas were characterized as controlled areas. After the quantitative and qualitative determination of the contaminated materials, the decontamination was planned and performed step by step: the contaminated materials were categorized according to their physical characteristics (scrap metals, plastic pipes, scales and residues, building materials, etc) and according to their level of radioactivity. Depending on the material type, different decontamination and disposal options were proposed; the most appropriate technique was chosen taking into account apart from technical issues, the legal framework, radiation protection issues, the opinion of the local authorities involved as well as the owner's wish. After taking away the biggest amount of the contaminated materials, an iterative process consisting of surveys and decontamination actions was performed in order to remove the residual traces of contamination from the area. During the final survey, no residual surface contamination was detected; some sparsely distributed low level contaminated materials deeply immersed into the soil were found and removed.

New views on treatment of aromatase inhibitors induced arthralgia.

BACKGROUND: Aromatase Inhibitor (AI) induced arthralgia is one of the most frequent side effects in breast cancer hormonal therapy, which may become severe in some cases affecting patients' quality of life. The purpose of this study is to investigate alternative treatment of arthralgia, as current treatment options may often prove to be inadequate. MATERIAL-METHODS: According to Morales et al, AI-associated arthralgia syndrome is characterized by tenosynovial changes in MRI, including fluid in tendon sheaths and joints. Initially, furosemide (20 mg per two days) was prescribed by our team, in order to minimize peripheral edema in women receiving aromatase inhibitors. The data collected demonstrated that 16 out of 18 patients had benefited from the addition of a diuretic agent in their adjuvant AI treatment as far as AI induced arthralgia is concerned as well. In this retrospective study, data from 288 women receiving an AI for non-metastatic breast cancer are analyzed in order to define whether chronic diuretic therapy could affect the impact of arthralgia on those patients. RESULTS: 42/288 Patients were receiving chronic diuretic therapy for heart disease or hypertension (Group A), while 246/288 patients had never received any diuretic medication (Group B). At 43.03 months of mean follow up, in Group A arthralgia was developed in 3/42 patients (6.97%) as opposed to 39/246 patients in Group B (15.85%) -p value: 0.01. Other parameters that could affect the impact of arthralgia in both Groups are also analyzed and taken under consideration. CONCLUSION: Despite the low number of patients and the retrospective nature of the study, there was a clear trend to a lower incidence of arthralgia in patients receiving chronic diuretic therapy. We believe that based on this hypothesis generating study further research should be done to assess the value of diuretic agents in the treatment of AI-associated arthralgia.

Kalman smoother based time-varying spectrum estimation of EEG during single agent propofol anesthesia.

A time-varying parametric spectrum estimation method for analyzing EEG dynamics is presented. EEG signals are first modeled as a time-varying auto-regressive stochastic process and the model parameters are estimated recursively with a Kalman smoother algorithm. Time-varying spectrum estimates are then obtained from the estimated parameters. The proposed method was applied to measurements collected during low dose propofol anesthesia. The method was able to detect changes of event related (de)synchronization type elicited by verbal command.

Time-varying spectrum estimation of heart rate variability signals with Kalman smoother algorithm.

A time-varying parametric spectrum estimation method for analyzing dynamics of heart rate variability (HRV) signals is presented. In the method, HRV signal is first modeled with a time-varying autoregressive model and the model parameters are solved recursively with a Kalman smoother algorithm. Time-varying spectrum estimates are then obtained from the estimated model parameters. The obtained spectrum can be further decomposed into separate components, which is especially advantageous in HRV applications where low frequency (LF) and high frequency (HF) components are generally aimed to be distinguished. As case studies, the dynamics of HRV signals recorded during 1) orthostatic test, 2) exercise test and 3) simulated driving task are analyzed.

On correlation between single-trial ERP and GSR responses: a principal component regression approach.

In this study we investigate the correlation between single-trial evoked brain responses and galvanic skin responses (GSR). The correlation between the two signals is examined by using a modified principal component regression based approach. A potential application of the study is to utilize the GSR measurements in a form of a prior information in the estimation of the brain potentials when only small number of trials is available.

Time-varying analysis of heart rate variability with kalman smoother algorithm.

A time-varying parametric spectrum estimation method for analyzing nonstationary heart rate variability signals is presented. In the method, the nonstationary signal is first modeled with time-varying autoregressive model and the model parameters are estimated recursively with a Kalman smoother algorithm. The spectrum estimates for each time are then obtained from the estimated model parameters. Statistics of the obtained spectrum estimates are derived using the error propagation principle. The obtained spectrum estimates can further be decomposed into separate components and, thus, the time-variation of low and high frequency components of heart rate variability can be examined separately.