Comparing oscillometric and tonometric methods to assess pulse wave velocity: a population-based study.

BACKGROUND: Oscillometric pulse wave velocity (o-PWV) represents an attractive, non invasive and non operator-dependent method to estimate arterial stiffness. Tonometric carotid-femoral measurements (cf-PWV),are considered the gold-standard for non-invasive aortic stiffness assessment. To date, no studies in the general population comparing the two methods have been performed. METHODS AND RESULTS: 1162 subjects were analysed. O-PWV and cf-PWV showed a mean difference of -0.31 m/sec(p ≤ 0.001). No significant differences between cf-PWV and o-PWVs were observed in patients without cardiovascular risk factors. The Bland and Altman analysis showed a moderate agreement between 24 h-o-PWV and cf-PWV (mean difference -0.99, LoA 4.23 to -6.22m/s). O-PWVs underestimate and overestimate arterial stiffness under and over 50 years respectively(p ≤ 0.001). Systolic blood pressure (SBP) and age differently impact cf-PWV and in office o-PWV variability (r2 0.35 and 0.88 respectively). In younger subjects a strong relationship between o-PWV and SBP reducing as age increases was found. Analysing the impact of age, an opposite trend was noticed. CONCLUSIONS: Oscillometric PWV estimates provide reliable values in the general population. An o-PWV tendency to underestimate arterial stiffness in younger subjects and in subjects with diseases known to increase arterial stiffness and to overestimate it with increasing age was found, even if scarcely relevant in clinical perspective. Overall the present findings underline an acceptable and satisfactory agreement between oscillometric and tonometric methods for the PWV assessment. KEY MESSAGES Oscillometric and tonometric PWV estimates showed a good and satisfactory agreement in the general population, above all in subjects without cardiovascular risk factors or a documented vascular damage. In comparison with tonometric values, oscillometric PWV estimates showed, however, the tendency to underestimate arterial stiffness in younger subjects and to overestimate it with increasing age, while diverging when diseases known to increase arterial stiffness are present. The magnitude of differences in PWV estimates between tonometric and oscillometric methods found in the general population appears most likely not to be significant in everyday clinical practice.

Intraoperative Blood Pressure Monitoring in Obese Patients.

BACKGROUND: The optimal method for blood pressure monitoring in obese surgical patients remains unknown. Arterial catheters can cause potential complications, and noninvasive oscillometry provides only intermittent values. Finger cuff methods allow continuous noninvasive monitoring. The authors tested the hypothesis that the agreement between finger cuff and intraarterial measurements is better than the agreement between oscillometric and intraarterial measurements. METHODS: This prospective study compared intraarterial (reference method), finger cuff, and oscillometric (upper arm, forearm, and lower leg) blood pressure measurements in 90 obese patients having bariatric surgery using Bland-Altman analysis, four-quadrant plot and concordance analysis (to assess the ability of monitoring methods to follow blood pressure changes), and error grid analysis (to describe the clinical relevance of measurement differences). RESULTS: The difference (mean ± SD) between finger cuff and intraarterial measurements was -1 mmHg (± 11 mmHg) for mean arterial pressure, -7 mmHg (± 14 mmHg) for systolic blood pressure, and 0 mmHg (± 11 mmHg) for diastolic blood pressure. Concordance between changes in finger cuff and intraarterial measurements was 88% (mean arterial pressure), 85% (systolic blood pressure), and 81% (diastolic blood pressure). In error grid analysis comparing finger cuff and intraarterial measurements, the proportions of measurements in risk zones A to E were 77.1%, 21.6%, 0.9%, 0.4%, and 0.0% for mean arterial pressure, respectively, and 89.5%, 9.8%, 0.2%, 0.4%, and 0.2%, respectively, for systolic blood pressure. For mean arterial pressure and diastolic blood pressure, absolute agreement and trending agreement between finger cuff and intraarterial measurements were better than between oscillometric (at each of the three measurement sites) and intraarterial measurements. Forearm performed better than upper arm and lower leg monitoring with regard to absolute agreement and trending agreement with intraarterial monitoring. CONCLUSIONS: The agreement between finger cuff and intraarterial measurements was better than the agreement between oscillometric and intraarterial measurements for mean arterial pressure and diastolic blood pressure in obese patients during surgery. Forearm oscillometry exhibits better measurement performance than upper arm or lower leg oscillometry.

Validity and reliability of lower-limb pulse-wave velocity assessments using an oscillometric technique.

NEW FINDINGS: What is the central question of this study? There is growing interest in the effects of sedentarism on central and peripheral cardiovascular health. To permit further investigation, including larger epidemiological studies, there is a need to identify arterial health assessment tools that are valid (accurate) and reliable (precise), yet practical. What is the main finding and its importance? Lower-limb vascular health (femoral-ankle pulse-wave velocity) can be determined in a supine position with accuracy and precision using an oscillometrically based device. This technology might help to improve our understanding of the pathological mechanisms linking cardiovascular disease to sedentarism, including the interaction between peripheral and central vasculature. ABSTRACT: There is a growing interest in the deleterious effects of sedentary behaviour on lower-limb arterial health. To permit further investigation, including larger epidemiological studies, there is a need to identify lower-limb arterial health assessment tools that are valid and reliable, yet simple to administer. In this study, we sought to determine the validity and between-day reliability of femoral-ankle pulse-wave velocity (faPWV) measures obtained using an oscillometrically based device (SphygmocCor XCEL) in supine and seated positions. Doppler ultrasound was used as the criterion. A total of 47 healthy adults were recruited for validity (n = 32) and reliability (n = 15) analyses. Validity was determined by measuring faPWV in seated and supine positions using the XCEL and Doppler ultrasound devices, in a randomized order. Between-day reliability was determined by measuring seated and supine faPWV using the XCEL on three different mornings, separated by a maximum of 7 days. The validity criterion [absolute standard error of estimate (aSEE) < 1.0 m s-1 ] was met in the supine [aSEE = 0.8 m s-1 , 95% confidence interval (CI) 0.4-1.0], but not in the seated (aSEE = 1.2 m s-1 , 95% CI 1.1-1.2) position. Intraclass correlation coefficient (ICC) estimates revealed that the XCEL demonstrated good reliability in the supine position (ICC = 0.83, 95% CI 0.65-0.93), but poor reliability in the seated position (ICC = 0.29, 95% CI 0.23-0.63). The oscillometric XCEL device can be used to determine lower-limb pulse-wave velocity with acceptable validity and reliability in the conventionally recommended supine position, but not in the seated position.

Effects of passive smoking on lung function tests in preschool children born late-preterm: a preventable health priority.

OBJECTIVE: Late-preterm delivery is known to be associated with potential adverse effects on lung development. Passive smoking may result in alterations of pulmonary function in infants born late-preterm. Impulse oscillometry (IOS) is a noninvasive, rapid, and practicable technique that can assess lung function. This study aimed to evaluate the effect of passive smoking on lung function tests in preschool children born late-preterm using IOS. METHODS: The study population consisted of a total of 139 children between 3 and 7 years of age born late-preterm who were being followed-up at our outpatient unit at the time of study period. Late-preterms were subcategorized according to presence or absence of exposure to passive smoking (PS). Those with and without exposure to passive smoking were referred to as PS group (56.1%, n = 78) and non-PS group (43.9%, n = 61), respectively. Resistance (R5-R20), reactance (X5-X20), and resonant frequency were measured by impulse oscillometry (IOS) at 5-20 Hz. RESULTS: Median R5-R20 and Z5 were significantly higher and median X10 was significantly lower in PS group compared to non-PS group (p < .05). CONCLUSIONS: This study demonstrated that passive smoking significantly increases peripheral airway resistance and seems to adversely affect lung function in children born late-preterm.

Novel methods of testing and calibration of oscillometric blood pressure monitors.

We present a robust method for testing and calibrating the performance of oscillometric non-invasive blood pressure (NIBP) monitors, using an industry standard NIBP simulator to determine the characteristic ratios used, and to explore differences between different devices. Assuming that classical auscultatory sphygmomanometry provides the best approximation to intra-arterial pressure, the results obtained from oscillometric measurements for a range of characteristic ratios are compared against a modified auscultatory method to determine an optimum characteristic ratio, Rs for systolic blood pressure (SBP), which was found to be 0.565. We demonstrate that whilst three Chinese manufactured NIBP monitors we tested used the conventional maximum amplitude algorithm (MAA) with characteristic ratios Rs = 0.4624±0.0303 (Mean±SD) and Rd = 0.6275±0.0222, another three devices manufactured in Germany and Japan either do not implement this standard protocol or used different characteristic ratios. Using a reference database of 304 records from 102 patients, containing both the Korotkoff sounds and the oscillometric waveforms, we showed that none of the devices tested used the optimal value of 0.565 for the characteristic ratio Rs, and as a result, three of the devices tested would underestimate systolic pressure by an average of 4.8mmHg, and three would overestimate the systolic pressure by an average of 6.2 mmHg.

Validating Reference Equations for Impulse Oscillometry in Healthy Mexican Children.

BACKGROUND: The impulse oscillometry system (IOS) measures the impedance (Z) of the respiratory system, but proper interpretation of its results requires adequate reference values. The objectives of this work were: (1) to validate the reference equations for the IOS published previously by our group and (2) to compare the adjustment of new available reference equations for the IOS from different countries in a sample of healthy children. METHODS: Subjects were healthy 4-15-y-old children from the metropolitan area of Mexico City, who performed an IOS test. The functional IOS parameters obtained were compared with the predicted values from 12 reference equations determined in studies of different ethnic groups. The validation methods applied were: analysis of the differences between measured and predicted values for each reference equation; correlation and concordance coefficients; adjustment by Z-score values; percentage of predicted value; and the percentage of patients below the lower limit of normality or above the upper limit of normality. RESULTS: Of the 224 participants, 117 (52.3%) were girls, and the mean age was 8.6 ± 2.3 y. The equations that showed the best adjustment for the different parameters were those from the studies by Nowowiejska et al (2008) and Gochicoa et al (2015). The equations proposed by Frei et al (2005), Hellinckx et al (1998), Kalhoff et al (2011), Klug and Bisgaard (1998), de Assumpção et al (2016), and Dencker et al (2006) overestimated the airway resistance of the children in our sample, whereas the equation of Amra et al (2008) underestimated it. In the analysis of the lower and upper limits of normality, Gochicoa et al equation was the closest, since 5% of subjects were below or above percentiles 5 and 95, respectively. The study found that, in general, all of the equations showed greater error at the extremes of the age distribution. CONCLUSIONS: Because of the robust adjustment of the present study reference equations for the IOS, it can be recommended for both clinical and research purposes in our population. The differential adjustment of other equations underlines the need to obtain local reference values.

Reference Equations for Impulse Oscillometry System Parameters in Healthy Brazilian Children and Adolescents.

BACKGROUND: The impulse oscillometry system is a noninvasive method of evaluating respiratory mechanics that is being increasingly used in the pediatric population. To date, no reference equations have been developed for healthy Brazilian children and adolescents. The purpose of the study was to determine the reference equations for impulse oscillometry system parameters in healthy children and adolescents. METHODS: We undertook an observational cross-sectional analytical study with healthy students age 6-14 y from educational institutions in the Greater Florianópolis area. Biometric data were evaluated (weight, height, body mass index, and body surface area) as predictors and for sample characterization. All participants were submitted to evaluation of respiratory mechanics using an oscillometry system following American Thoracic Society standards. Three tests were recorded, with data acquisition for ≥20 s. For data normality verification, the Kolmogorov-Smirnov test was applied, and Pearson's correlation test identified the relationship between the predicted values of height, age, and weight and the oscillometric variables of resistance at 5 and 20 Hz reactance; respiratory impedance at 5 Hz resonant frequency; and reactance area. Models were developed using simple linear regression and multiple analyses. RESULTS: After the recruitment of 864 children, 123 subjects with an average age of 10.0 ± 2.4 y for boys and 9.9 ± 2.4 y for girls (P = .94) were considered for final analysis. Correlations were identified between the dependent and predictor oscillometric variables, with height identified as having the greatest predictive power in the equations developed for boys in all oscillometric parameters, with a mean adjusted R(2) of 46.51%. Age had greater influence on resonant frequency (adjusted R(2) = 40.1%) and reactance area (adjusted R(2) = 48.8%) for girls. CONCLUSIONS: Reference equations were developed for males and females, and height was the most influential predictor variable for most impulse oscillometry system parameters in the population studied.

An algorithm for on-line detection of high frequency oscillations related to epilepsy.

Recent studies suggest that the appearance of signals with high frequency oscillations components in specific regions of the brain is related to the incidence of epilepsy. These oscillations are in general small in amplitude and short in duration, making them difficult to identify. The analysis of these oscillations are particularly important in epilepsy and their study could lead to the development of better medical treatments. Therefore, the development of algorithms for detection of these high frequency oscillations is of great importance. In this work, a new algorithm for automatic detection of high frequency oscillations is presented. This algorithm uses approximate entropy and artificial neural networks to extract features in order to detect and classify high frequency components in electrophysiological signals. In contrast to the existing algorithms, the one proposed here is fast and accurate, and can be implemented on-line, thus reducing the time employed to analyze the experimental electrophysiological signals.

Error mechanisms of the oscillometric fixed-ratio blood pressure measurement method.

The oscillometric fixed-ratio method is widely employed for non-invasive measurement of systolic and diastolic pressures (SP and DP) but is heuristic and prone to error. We investigated the accuracy of this method using an established mathematical model of oscillometry. First, to determine which factors materially affect the errors of the method, we applied a thorough parametric sensitivity analysis to the model. Then, to assess the impact of the significant parameters, we examined the errors over a physiologically relevant range of those parameters. The main findings of this model-based error analysis of the fixed-ratio method are that: (1) SP and DP errors drastically increase as the brachial artery stiffens over the zero trans-mural pressure regime; (2) SP and DP become overestimated and underestimated, respectively, as pulse pressure (PP) declines; (3) the impact of PP on SP and DP errors is more obvious as the brachial artery stiffens over the zero trans-mural pressure regime; and (4) SP and DP errors can be as large as 58 mmHg. Our final and main contribution is a comprehensive explanation of the mechanisms for these errors. This study may have important implications when using the fixed-ratio method, particularly in subjects with arterial disease.

Pediatric reference values of carotid-femoral pulse wave velocity determined with an oscillometric device.

BACKGROUND: A semi-automated devise for oscillometric measurement (Vicorder) of carotid-femoral pulse wave velocity (cfPWV) has been considered to be especially suited for multicenter studies in children and adolescents. METHODS: Within a healthy pediatric population (156 boys/158 girls; mean age 10.8 years, range 5.0-19.6 years), the transit time of the pulse wave was measured oscillometrically (Vicorder) between a carotid and femoral cuff. For calculation of cfPWV, the traveled path length was set to 80% of the direct distance between both sites of measurement. Reference tables were generated using the maximum-likelihood curve-fitting technique and SD scores were calculated. Normalizing the same set of data with reference values specific for applanation tonometry yielded Z(at)values. Effects of sex, age, height, weight, BMI, blood pressure (BP), and heart rate on cfPWV as well as the correlation between sex-specific age-related and height-related Z(osci) and Z(at)were investigated. RESULTS: Sex-specific reference values and curves for cfPWV as a function of age and height are presented. cfPWV correlated positively with age, height, weight, SBP, mean arterial BP, and sex (each P  <  0.005). Multiple regression analysis identified age, sex, and mean arterial pressure as significant independent predictors of cfPWV explaining 42% of the overall variability. Strong linear relationships between Z(osci) and Z(at) were noted and per sex a set of age and height-related equation for conversion was derived: Z(at),age  = -0.22 + 0.68 × Z(osci),age; r  =  0.98 and Z(at),height  = -0.33 + 0.66 × Z(osci),height; r  =  0.99 in boys and Z(at),age  = -0.61 + 0.81 × Z(osci),age; r  =  0.98 and Z(at),height  = -0.73 + 0.72 × Z(osci),height; r  =  0.97 in girls (each P  <  0.001). CONCLUSION: A strong linear association between height-related oscillometric and tonometric Z-scores was observed. Age-related Z-scores are of limited value when comparing results across different populations and methods.

A study of the use of impulse oscillometry in the evaluation of children with asthma: analysis of lung parameters, order effect, and utility compared with spirometry.

BACKGROUND: The ability to objectively measure lung function in children is critical in the assessment and treatment of asthma in this age group. We thus determined the effectiveness of impulse oscillometry (IOS) as a non-invasive technique to assess lung function in children and in comparison to spirometry for sensitivity and specificity, testing variability, and the order effect of sequential testing of IOS and spirometry. METHODS: One hundred seventeen children sequentially evaluated in a pediatric clinic and under medical care for disease, were asked to perform IOS and spirometry. The utility of IOS and spirometry in differentiating children that had asthma versus those children who did not was then analyzed. RESULTS: In the primary analysis (n = 117), bronchodilator response using IOS distinguished asthmatics from non-asthmatics, P = 0.0008 for R10. Receiver-operator characteristic curve (ROC) analysis of R10 bronchodilator response at the best cut-off (-8.6% change) correctly identified 77% of patients with asthma and excluded 76% of non-asthmatics. Amongst those children able to perform spirometry (asthmatics, n = 66; non-asthmatics, n = 16), FEV(1) did not reveal a difference between these two groups, while area of reactance (AX) did distinguish these groups (P = 0.0092). Sequential testing of IOS and then spirometry (n = 47) showed a significant decrement in lung function as determined by IOS following performance of spirometry (P = 0.0309). CONCLUSION: In the diagnosis and management of children with lung disease, IOS is a non-invasive approach that easily and objectively measures lung impedance and should be considered as both an adjunct, and in some situations, an alternative to standard spirometry.

Model-based error analysis of the oscillometric fixed-ratio blood pressure measurement method.

We investigated factors affecting the accuracy of the oscillometric fixed-ratio blood pressure measurement method. We specifically applied a parametric sensitivity analysis to a mathematical model of oscillometry. We found that changes in arterial stiffness at zero transmural pressure and pulse pressure represent major factors that can potentially cause large error in the method. In particular, our theoretical analysis demonstrates that the fixed-ratio method predicts (1) higher systolic and lower diastolic blood pressures as the artery stiffen over the zero transmural pressure regime and (2) higher systolic and lower diastolic blood pressures as the pulse pressure increases. Further, the impact of pulse pressure on these errors is more obvious as the artery stiffens.

Tolerability of the Oscar 2 ambulatory blood pressure monitor among research participants: a cross-sectional repeated measures study.

BACKGROUND: Ambulatory blood pressure monitoring (ABPM) is increasingly used to measure blood pressure (BP) in research studies. We examined ease of use, comfort, degree of disturbance, reported adverse effects, factors associated with poor tolerability, and association of poor tolerability with data acquisition of 24-hour ABPM using the Oscar 2 monitor in the research setting. METHODS: Sixty adults participating in a research study of people with a history of borderline clinic BP reported on their experience with ABPM on two occasions one week apart. Poor tolerability was operationalized as an overall score at or above the 75th percentile using responses to questions adapted from a previously developed questionnaire. In addition to descriptive statistics (means for responses to Likert-scaled "0 to 10" questions and proportions for Yes/No questions), we examined reproducibility of poor tolerability as well as associations with poor tolerability and whether poor tolerability was associated with removal of the monitor or inadequate number of BP measurements. RESULTS: The mean ambulatory BP of participants by an initial ABPM session was 148/87 mm Hg. After wearing the monitor the first time, the degree to which the monitor was felt to be cumbersome ranged from a mean of 3.0 to 3.8, depending on whether at work, home, driving, or other times. The most bother was interference with normal sleeping pattern (mean 4.2). Wearers found the monitor straightforward to use (mean 7.5). Nearly 67% reported that the monitor woke them after falling asleep, and 8.6% removed it at some point during the night. Reported adverse effects included pain (32%), skin irritation (37%), and bruising (7%). Those categorized as having poor tolerability (kappa = 0.5 between sessions, p = 0.0003) were more likely to report being in fair/poor health (75% vs 22%, p = 0.01) and have elevated 24-hour BP average (systolic: 28% vs 17%, p = 0.56; diastolic: 30% vs 17%, p = 0.37). They were also more likely to remove the monitor and have inadequate numbers of measurements. CONCLUSIONS: The Oscar 2 ABPM device is straightforward to use but can interfere with sleep. Commonly reported adverse effects include pain, skin irritation, and bruising. Those who tolerate the monitor poorly are more likely to report being in fair or poor health and to remove it, particularly at night.

Scalp-recorded high-frequency oscillations in childhood sleep-induced electrical status epilepticus.

Because high-frequency oscillations (HFOs) may affect normal brain functions, we examined them using electroencephalography (EEG) in epilepsy with continuous spike-waves during slow-wave sleep (CSWS), a condition that can cause neuropsychological regression. In 10 children between 6 and 9 years of age with epilepsy with CSWS or related disorders, we investigated HFOs in scalp EEG spikes during slow-wave sleep through temporal expansion of the EEG traces with a low-cut frequency filter at 70 Hz as well as through time-frequency power spectral analysis. HFOs (ripples) concurrent with spikes were detected in the temporally expanded traces, and the frequency of the high-frequency peak with the greatest power in each patient's spectra ranged from 97.7 to 140.6 Hz. This is the first report on the detection of HFOs from scalp EEG recordings in epileptic patients. We speculate that epileptic HFOs may interfere with higher brain functions in epilepsy with CSWS.

Delay stabilization of periodic orbits in coupled oscillator systems.

We study diffusively coupled oscillators in Hopf normal form. By introducing a non-invasive delay coupling, we are able to stabilize the inherently unstable anti-phase orbits. For the super- and subcritical cases, we state a condition on the oscillator's nonlinearity that is necessary and sufficient to find coupling parameters for successful stabilization. We prove these conditions and review previous results on the stabilization of odd-number orbits by time-delayed feedback. Finally, we illustrate the results with numerical simulations.

Complex dynamics and synchronization of delayed-feedback nonlinear oscillators.

We describe a flexible and modular delayed-feedback nonlinear oscillator that is capable of generating a wide range of dynamical behaviours, from periodic oscillations to high-dimensional chaos. The oscillator uses electro-optic modulation and fibre-optic transmission, with feedback and filtering implemented through real-time digital signal processing. We consider two such oscillators that are coupled to one another, and we identify the conditions under which they will synchronize. By examining the rates of divergence or convergence between two coupled oscillators, we quantify the maximum Lyapunov exponents or transverse Lyapunov exponents of the system, and we present an experimental method to determine these rates that does not require a mathematical model of the system. Finally, we demonstrate a new adaptive control method that keeps two oscillators synchronized, even when the coupling between them is changing unpredictably.

Quantifying stochasticity in the dynamics of delay-coupled semiconductor lasers via forbidden patterns.

We quantify the level of stochasticity in the dynamics of two mutually coupled semiconductor lasers. Specifically, we concentrate on a regime in which the lasers synchronize their dynamics with a non-zero lag time, and the leader and laggard roles alternate irregularly between the lasers. We analyse this switching dynamics in terms of the number of forbidden patterns of the alternate time series. The results reveal that the system operates in a stochastic regime, with the level of stochasticity decreasing as the lasers are pumped further away from their lasing threshold. This behaviour is similar to that exhibited by a single semiconductor laser subject to external optical feedback, as its dynamics shifts from the regime of low-frequency fluctuations to coherence collapse.

Interplay of time-delayed feedback control and temporally correlated noise in excitable systems.

The interplay of time-delayed feedback and temporally correlated coloured noise in a single and two coupled excitable systems is studied in the framework of the FitzHugh-Nagumo (FHN) model. By using coloured noise instead of white noise, the noise correlation time is introduced as an additional time scale. We show that in a single FHN system the major time scale of oscillations is strongly influenced by the noise correlation time, which in turn affects the maxima of coherence with respect to the delay time. In two coupled FHN systems, coloured noise input to one subsystem influences coherence resonance and stochastic synchronization of both subsystems. Application of delayed feedback control to the coloured noise-driven subsystem is shown to change coherence and time scales of noise-induced oscillations in both systems, and to enhance or suppress stochastic synchronization under certain conditions.

Neocortical hyperexcitability in a genetic model of absence seizures and its reduction by levetiracetam.

PURPOSE: To study the effect of the antiepileptic drug levetiracetam (LEV) on the patterns of intrinsic optical signals (IOSs) generated by slices of the somatosensory cortex obtained from 3- and 6-month-old WAG/Rij and age-matched, nonepileptic control (NEC) rats. METHODS: WAG/Rij and NEC animals were anesthetized with enfluorane and decapitated. Brains were quickly removed, and neocortical slices were cut coronally with a vibratome, transferred to a submerged tissue chamber, and superfused with oxygenated artificial cerebrospinal fluid (aCSF). Slices were illuminated with a dark-field condensor and examined with a x2.5 objective; images were processed with a real time digital video image-enhancement system. Images were acquired before (background) and during electrical stimulation with a temporal resolution of 10 images/s and were displayed in pseudocolors. Extracellular stimuli (200 micros; <4 V) were delivered through bipolar stainless steel electrodes placed in the white matter. RESULTS: IOSs recorded in NEC slices bathed in control aCSF became less intense and of reduced size with age (p < 0.05); this trend was not seen in WAG/Rij slices. Age-dependent decreases in IOS intensity and area size were also seen in NEC slices superfused with aCSF containing the convulsant 4-aminopyridine (4-AP, 5 microM); in contrast, significant increases in both parameters occurred with age in 4-AP-treated WAG/Rij slices (p < 0.05). Under any of these conditions, the IOS intensity and area size slices were larger in WAG/Rij than in NEC slices. LEV (50-500 microM) application to WAG/Rij slices caused dose-dependent IOS reductions that were evident both in control and in 4-AP-containing aCSF and were more pronounced in 6-month-old tissue. CONCLUSIONS: These data demonstrate age-dependent IOS modifications in NEC and WAG/Rij rat slices and identify a clear pattern of hyperexcitability that occurs in 6-month-old WAG/Rij neocortical tissue, an age when absence seizures occur in all animals. The ability of LEV to reduce these patterns of network hyperexcitability supports the potential use of this new antiepileptic drug in primary generalized epileptic disorders.

[Value of blood pressure of adults depending on method of measurement]. / Wartosci cisnienia tetniczego krwi u doroslych osób w zaleinosci od metody pomiaru.

UNLABELLED: Hypertension is currently one of the most common diseases of circulation system within Polish population. This fact implies an urgent need of introducing efficient prevention concerning proper blood pressure measurement not only in medical centers but at home of patients as well. Blood pressure measurement of brachial taking by mercurial sphygmomanometer is an advisable method recommended by World Health Organization and International Society of Hypertension. In practice, however, other methods are used by patients and blood pressure is often of measure wrist. THE AIM of the research was the comparison of results of different method of measurement blood pressure of adults. The measurement was taken with three types of instruments at different parts of upper limb: arm and wrist. MATERIAL AND METHODS: 105 persons, 75 men and 30 women at age 46,3+/-12,1 years, were examined by taking the measurement of vascular blood pressure at rest. The measurement was taken at left upper limb after fifteen minutes of rest. The first measurement was taken with mercurial sphygmomanometer. Subsequently, the automatic wrist vascular blood pressure instrument made by OMRON R-1 was used; third measurement: automatic brachial vascular blood pressure instrument made by OMRON M5-1. RESULTS: Average values of systolic vascular blood pressure measured with mercurial sphygmomanometer were 122,1+/-18,9 mmHg, diastolic pressure were 81,7+/-9,9 mmHg. Average values of systolic vascular blood pressure measured with automatic wrist vascular blood pressure instrument were higher 131,3+/-21,0 mmHg, diastolic pressure were 85,3 + 12,1 mmHg (p<0,05). Average values of systolic vascular blood pressure measured with automatic brachial vascular blood pressure instrument were higher too: 129,6+/-19,9 mmHg, diastolic pressure were 80,5+/-11,4 mmHg (p<0,05). Measurements taken with automatic instrument were considerably statistically higher than with mercurial sphygmomanometer. CONCLUSION: 1. Measurements of vascular blood pressure at rest taken with automatic instruments (wrist and brachial one) were considerably higher than with mercurial sphygmomanometer. The differences were mainly concerning the values of systolic vascular blood pressure. The place of measurement (arm and wrist) had no influence on the result. 2. In comparison to mercurial sphygmomanometer, the error statistically essential must be taken into account during the interpretation of results obtained by measurement taken with brachial and wrist instruments. The instruments may be used for comparison of the successive results of the same person only. 3. The measurements taken with mercurial sphygmomanometer should remain a basic tool in hypertension diagnosis and control.