Małgorzata Tafil-Klawe

Impaired blood pressure variability in chronic fatigue syndrome—a potential biomarker

INTRODUCTIONnAutonomic dysfunction is common in chronic fatigue syndrome (CFS). This study set out to derive an autonomic biomarker using a comprehensive assessment of heart rate and blood pressure variability.nnnMETHODSnHeart rate and non-invasive continuous blood pressure measurements (task force monitor) at rest and on standing were performed in CFS (Fukuda nu2009=u200968) and matched controls (nu2009=u200968) to derive high frequency (HF; parasympathetic) and low frequency (LF; sympathetic) heart rate variability (HRV), systolic (SBPV) and diastolic (DBPV) blood pressure variability. Variables of significance were combined using receiver operator curves to explore the diagnostic utility of parameters particularly at rest.nnnRESULTSnAt rest, LF-HRV (sympathetic) was significantly increased in CFS compared to controls, while parasympathetic markers were significantly reduced (Pu2009=u20090.006). Total DBP spectral power was increased (Pu2009=u20090.0003) across all domains, with a shift towards sympathetic and away from parasympathetic SBPV (Pu2009=u20090.05). On standing, overall SBPV response was significantly reduced with reductions in both sympathetic and parasympathetic components of SBPV (all Pu2009<u20090.0001). Change in LF-DBP and relative balance of LF/HF DBP on standing differed between CFS and controls (Pu2009<u20090.0001). Using the 85% sensitivity levels, we determined a threshold for three chosen resting BPV parameters of LF DBP >3.185, rest HF DBP >0.86, rest total DBP >7.05. Achieving all of these differentiated between CFS and controls with 77% sensitivity and 53% specificity.nnnCONCLUSIONnThis study has shown that there are objectively measured abnormalities of blood pressure variability in CFS and that these abnormalities have the potential to be a bedside diagnostic tool.

Sympatho-inhibitory baroreflex in conscious rabbits: simultaneous recordings of sympathetic and aortic nerve activity

The purpose of this study was to evaluate simultaneously the activity of afferent and efferent neuronal pathways of the sympatho-inhibitory baroreceptor reflex in conscious rabbits. Bipolar electrodes were implanted around the intact aortic nerve and cervical sympathetic trunk. Baroreceptor activity and sympathetic discharges were continuously recorded along with mean blood pressure. The baroreceptor reflex response was evoked by changes in mean arterial pressure induced by i.v. administration of phenylephrine 10 micrograms/kg and sodium nitroprusside 10 micrograms/kg. The baroreflex was analysed as parallel changes of afferent and efferent activities per mmHg of mean blood pressure rise or fall. This method of investigation of baroreflex responsiveness permits analysis of afferent and efferent neural activities under different behavioural conditions in conscious animals.

Thermal and hemodynamic response to whole-body cryostimulation in healthy subjects.

Whole-body cryotherapy (WBC) is an increasing applied cryotherapeutic method, that involves application of a cryotherapeutic factor to stimulate the body by the means of intense hypothermia of virtually the bodys entire area. This method is still not well recognized in Western Europe. However in recent years it is becoming increasingly popular in sports medicine and also in clinical application. Cryotherapeutic agents used in WBC are considered to be a strong stress stimulus which is associated with a variety of changes in functional parameters, particularly of the cardiovascular and autonomic nervous systems. However, such strong influence upon the entire body could be associated with the risk of unexpected reactions which might be dangerous for homeostasis. The present study evaluated the complex hemodynamic physiological reactions in response to WBC exposure in healthy subjects. Thirty healthy male volunteers participated. Each subject was exposed to WBC (-120°C) for 3-min. None of the participants had been exposed to such conditions previously. The research was conducted with modern and reliable measurements techniques, which assessed complex hemodynamic reactions and skin temperature changes non-invasively. All measurements were performed four times (before WBC, after WBC, WBC+3h and WBC+6h) with a Task Force Monitor (TFM - CNSystems, Medizintechnik, Gratz, Austria). Body superficial temperature was measured by infrared thermographic techniques - infra-red camera Flir P640 (Flir Systems Inc., Sweden). Our results show a significant decrease in heart rate, cardiac output, and increase in stroke volume, total peripheral resistance and baroreceptors reflex sensitivity. These changes were observed just after WBC exposure. At stages WBC+3h and WBC+6h there was observed a significant drop in baroreceptors reflex sensitivity due to increased thermogenesis. In conclusion, the present findings suggest that WBC strongly stimulates the baroreceptor cardiac reflex in response to body fluid changes which sequentially modulate HR and BP control in supine and resting healthy subjects. The study was performed on randomized and homogenic group of young healthy subjects. Our findings are important for WBC safety determination in research and clinical studies.

Cardiovascular and autonomic responses to whole-body cryostimulation in essential hypertension.

Over recent years, a considerable increase in the popularity of cryostimulation and whole body cryotherapy (WBC) procedures has occurred both among healthy individuals and in various groups of patients, including those with primary untreated hypertension. The aim of this study was to compare the effects of WBC on the functional parameters of cardiovascular system in normotensive and primarily hypertensive individuals. The study included 26 young male volunteers with normal blood pressure range (NormoBP) and 13 with essential arterial hypertension (HyperBP). Each subject was exposed to cryotherapeutic factor (whole-body cryotherapy/cryostimulation, WBC) at a temperature of approximately -115°C to -125°C for a period of 3 min. The cardiovascular and autonomic parameters were measured noninvasively with Task Force® Monitor. Measurements in a supine position and tilt test were performed before WBC and after WBC. Our study revealed that cryogenic temperatures exert strong modulatory effect on the cardiovascular system. Both groups showed adaptive changes of myocardial and vascular parameters in response to rapid cooling of virtually the whole body surface. While the profiles of some of these changes were similar in both the groups, also several considerable intergroup differences were documented. Consequently, the cryostimulation and cryotherapy treatment should be prescribed carefully to individuals who present with cardiovascular failure of any degree.

Whole-body cryostimulation increases parasympathetic outflow and decreases core body temperature

The cardiovascular, autonomic and thermal response to whole-body cryostimulation exposure are not completely known. Thus the aim of this study was to evaluate objectively and noninvasively autonomic and thermal reactions observed after short exposure to very low temperatures. We examined 25 healthy men with mean age 30.1 ± 3.7 years and comparable anthropomorphical characteristic. Each subject was exposed to cryotherapeutic temperatures in a cryogenic chamber for 3 min (approx. -120 °C). The cardiovascular and autonomic parameters were measured noninvasively with Task Force Monitor. The changes in core body temperature were determined with the Vital Sense telemetric measurement system. Results show that 3 min to cryotherapeutic temperatures causes significant changes in autonomic balance which are induced by peripheral and central blood volume changes. Cryostimulation also induced changes in core body temperature, maximum drop of core temperature was observed 50-60 min after the stimulation. Autonomic and thermal reactions to cryostimulation were observed up to 6 h after the exposure and were not harmful for examined subjects.

Age-related changes in cognitive function and postural control in Parkinson’s disease

Background and aimsThis study objectively analyzed postural instability and cognitive function in patients with Parkinson’s disease (PD) and a group of healthy elderly and middle-aged individuals.MethodsThe study included ten healthy middle-aged individuals (range 42–57xa0years), 14 healthy elderly individuals (range 60–90xa0years) and 15 PD patients (range 58–93xa0years). Center of pressure (COP) parameters were determined by means of computed static posturography during free standing with open and closed eyes. The level of cognitive functioning was examined with mini mental state examination (MMSE) and counting backwards test (CBT).ResultsParkinson’s disease patients showed significantly lower MMSE scores compared to healthy middle-aged (pxa0=xa00.004) and elderly individuals (pxa0=xa00.03). Mean duration of CBT in PD patients was significantly longer than in healthy subjects. COP parameters correlated with age of subjects and cognitive function (MMSE score). No significant differences in any stabilographic parameters were observed between healthy elderly subjects and PD patients.ConclusionsAge is the most significant factor impacting upon the static balance of older individuals during free standing. Compared to middle-aged and elderly individuals without central nervous system impairment, patients with PD present with significant delay in cognitive processes associated with executive function.

Daytime Acute Non-Visual Alerting Response in Brain Activity Occurs as a Result of Short- and Long-Wavelengths of Light

Very recent preliminary findings concerning the alerting capacities of light stimulus with long-wavelengths suggest the existence of neural pathways other than melatonin suppression that trigger the nonvisual response. Though the nonvisual effects of light during the daytime have not been investigated thoroughly, they are definitely worth investigating. The purpose of the present study is to enrich existing evidence by describing how quantitative electroencephalography (EEG) signal analysis can give insight into the measurement of the acute nonvisual response observed in brain states generated during daytime exposure to light (when melatonin secretion is negligible). EEG changes were assessed in 19 subjects during the daytime while being exposed to both short- (blue, 72 &mgr;W/cm2) and long-wavelength (red, 18 &mgr;W/cm2) radiation. We showed that artificial light stimulus as low as 40 lux decreases the synchronization in the upper theta, lower alpha, and upper alpha EEG activity spectrum. The direction of change was consistent with an increased level of alertness. We can conclude that EEG analysis is an indicator of the acute nonvisual response to daytime light. Surprisingly, the response was more spread over the scalp during exposure to red light than to blue light. According to our study, the response to long-wavelength stimulus that inhibits sleepiness, thereby inducing alertness, also takes place at the bright part of the 24-hr day when human beings are naturally predisposed to be exposed to a high level of sunlight: between 12 and 4 PM. The absorption spectrum of the nonvisual system seems to have different characteristics than was previously suspected: it is not dominated by the short-wavelengths, but involves long-wavelengths. Since we observed the predominance of the red-light alerting effect over the blue-light in this experiment, we conclude that more than one mechanism, beyond the melatonin pathway, must be involved.

Reflex influence of carotid baroreceptor inactivation on respiratory resistance in humans.

Our previous study demonstrated that selective carotid baroreceptors activation decreases airway resistance. The aim of the present study was to evaluate the effect of carotid baroreceptor inactivation on the reflex change of respiratory resistance. Twenty healthy men aged between 20 and 25 were included in the study. Selective inactivation of carotid baroreceptors was induced by generating a positive pressure of 40 mmHg for 5 s in two capsules placed bilaterally on the neck over the bifurcation of the carotid arteries. The oscillatory method (Siregnost FD5, Siemens) was used to measure continuously respiratory resistance. Inactivation of carotid baroreceptors produced a short increase in respiratory resistance by 0.39 ± 0.01(SE) mbar/l/s, i.e., 21.7% above the resting level. We conclude that in humans, carotid baroreceptors might have a background contribution to bronchodilator tone. This observation seems to be important for clinical situations of impairment of baroreflex function.

Hemodynamic, Autonomic, and Vascular Function Changes after Sleep Deprivation for 24, 28, and 32 Hours in Healthy Men

This study aimed to analyze the impact of sleep deprivation (SD) on cardiac, hemodynamic, and endothelial parameters and to determine whether these are sustained with increased periods of SD. The study included 60 healthy men (mean: age 31.2±6.3 years; body mass index 24.6±2.6 kg/m2). Hemodynamic parameters, parameters of myocardial contractility, spectral analysis of heart rate (HR) and blood pressure (BP) variability, and the sensitivity of arterial baroreflex function were evaluated. Biochemical tests were performed to assess L-arginine (L-Arg) and asymmetric dimethylarginine (ADMA) levels in reflection of endothelial nitric oxide synthase ability. Measurements of cardiovascular system parameters were obtained at 9 a.m. (baseline) on the first day of the study and 9 a.m. (24-h SD), 1 p.m. (28-h SD), and 5 p.m. (32-h SD) on the second day. Blood samples for evaluating biochemical parameters were obtained at baseline and after 24-h SD. ANOVA Friedmans test revealed a significant effect for time in relation to HR (χ2=26.04, df=5, p=0.000), systolic BP (χ2=35.98, df=5, p=0.000), diastolic BP (χ2=18.01, df=5, p=0.003), and mean BP (χ2=28.32, df=5, p=0.000). L-Arg and ADMA levels changed from 78.2±12.9 and 0.3±0.1 at baseline to 68.8±10.2 and 0.4±0.1 after 24-hr SD, respectively (p=0.001, p=0.004). SD in healthy men is associated with increases in BP, which appear to occur after 24 hours of SD and are maintained over increasing periods of SD. The observed hemodynamic changes may have resulted due to disordered vascular endothelial function, as reflected in alterations in L-Arg and ADMA levels.

Do Changes in Hemodynamic Parameters Depend Upon Length of Sleep Deprivation? Comparison Between Subjects With Normal Blood Pressure, Prehypertension, and Hypertension

The main objective of the study was to analyze the impact of sleep deprivation upon hemodynamic and autonomic parameters in subjects with normal blood pressure (BP) compared to prehypertension and hypertension at 24, 28, and 32 h of total sleep deprivation (TSD). Thirty volunteers, healthy men with current medical tests indicating the absence of disease took part in the study. After physical examination (basic neurological, clinical examination, echocardiography and doppler ultrasound of the renal arteries, evaluation of the autonomic nervous system) subjects were divided into three groups: I – normotensive, II – pre-hypertensive, III – hypertensive (age: 31.2 ± 2.1 vs. 33.5 ± 2.7 vs. 36.8 ± 2.7 years, p > 0.05; BMI: 25.2 ± 0.8 vs. 29.0 ± 1.5 vs. 26.4 ± 1.0 kg/m2, p > 0.05). Hemodynamic and autonomic parameters were automatically measured at rest and in a tilted position with a Task Force Monitor. The Task Force Monitor consists of electrocardiography, impedance cardiography, oscillometric, and continuous BP measurement. Mixed models with random effects was applied in order to analyze the parameters’ dependence on the time and the group of patients. One-way ANOVA or Kruskal–Wallis test were used to detect differences between normotensive, pre-hypertensive and hypertensive groups in each time point. In the pre-hypertensive group 28-h TSD resulted in increased vagal outflow [changes in high frequency heart rate (HR) variability, p = 0.0189], as evidenced by decreased HR (p = 0.0293). Moreover after 24-h TSD and 28-h TSD we observed changes in BP parameters. In hypertensive group, the most important changes in hemodynamic parameters: systolic blood pressure (sBP, p = 0.0031), diastolic blood pressure (dBP, p = 0.0136), cardiac output (CO, p = 0.0439) and changes in HR (p = 0.0063) after tilt test were observed after 32-h TSD. In conclusion, our results show that changes in hemodynamic parameters during sleep deprivation depend on the baseline BP and duration of TSD. What is important, both groups reported a decrease of sBP and dBP during the TSD (pre-hypertensive group after 24, 28-h TSD; hypertensive group after 32-h TSD. In our opinion, this is the first study which considers three homogenous groups in terms of gender: only men, during different points of acute TSD: 24, 28, and 32 h of TSD in laboratory condition.