Ambulatory Monitoring Device Research Articles

Real-time estimation of aerodynamic features for ambulatory voice biofeedback.

The development of ambulatory voice monitoring devices has the potential to improve the diagnosis and treatment of voice disorders. In this proof-of-concept study, real-time biofeedback is incorporated into a smartphone-based platform that records and processes neck surface acceleration. The focus is on utilizing aerodynamic measures of vocal function as a basis for biofeedback. This is done using regressed Z-scores to compare recorded values to normative estimates based on sound pressure level and fundamental frequency. Initial results from the analysis of different voice qualities suggest that accelerometer-based estimates of aerodynamic parameters can be used for real-time ambulatory biofeedback.

PP.17.26

Objective: Average real variability (ARV), as a reliable index has been proposed to define blood pressure oscillations occurring trough 24-hour, but a normal range or cut off point has not been established. Therefore, the aim of the present study is to define low, medium and high variability range and to assess the relationship between these groups of variability and blood pressure values. Design and method: This observational study was conducted between 2012–2014 in County Clinical Hospital- Department for Internal Medicine IV, Targu-Mures, Romania and included 102 patients with treated hypertension. Circadian blood pressure was recorded with a validated 24-hour ambulatory monitoring device (Meditech 05 ABPM). Blood pressure variability was calculated according to the formula of average real variability, using a computerized soft. Based on variability, patients were divided in to low, medium or high variability group. Blood samples were collected regarding cardiovascular risk factors (total cholesterol, triglycerides, blood glucose, creatinine). Characteristics of the groups were compared by one way-ANOVA test, correlations were analysed with Pearson's test, categorical variables were compared with chi2 test, using Graph Pad Prism 5 statistical program. Results: Low variability was defined as ARV between 4.32–9.85 mmHg (34 patients), medium 9.86–12.87 mmHg (45 patients), high variability between 12.88–16.87 mmHg (23 patients). Mean age was statistically significant among the groups, 57.02 ± 13.52, versus 62.42 ± 11.01 versus 65.69 ± 13.1 years, p = 0.02. The 24-hour systolic blood pressure differed significantly between the groups, 131,38 ± 16.31 versus 136,13 ± 12.04 versus140.9 ± 12.21, p = 0.037. Although, glomerular filtration rate was lowest in the high variability group 71,12 ± 28,91 the difference was statistically not significant (p = 0.88). In the high variability group positive correlation was found between blood pressure variability and 24-hour systolic blood pressure (p = 0.02, r2 = 0.2196, CI:0.06984 to 0.7383). Conclusions: High blood pressure variability could be defined as ARV greater than 12.88 mmHg. Elderly patients show greater blood pressure values, higher blood pressure variability and impaired kidney function. To prevent end organ damage, evaluation and reduction of blood pressure variability could be at least as important as blood pressure lowering.

OP33 – 2365: Treatment with botulinum toxin of children with cerebral palsy has no added therapeutical value or cost-effectiveness for gross motor function, everyday physical activity levels or quality of life when combined with intensive functional physiotherapy

Objective Since 20 years, children with spastic CP are increasingly treated with botulinum toxin typeA (BtA) followed by intensive physiotherapy (iPT). The added value of BtA remains unclear. We therefore compared (cost-)effectiveness of BtA+iPT versus only iPT treatment in a (partly) randomized controlled trial. Methods Sixty-five children aged 4–12 years participated, 41 received BtA+iPT and 24 only iPT. Measurements were performed after a 12-week iPT period (primary endpoint) and 12 weeks thereafter (24week follow-up). Primary outcome measures were: actual everyday physical activity levels measured with ambulatory monitoring devices (Actigraph-AG, 7day monitoring), (health related) quality of life measured with several questionnaires (Health Utility Index, Child Health Questionnaire, DISABKIDS-questionnaires), and gross motor function measured with the GMFM (item set version). Economic evaluation was performed according to Dutch guidelines taking a societal perspective. Results No statistically significant evidence was found for added value of BtA injections in BtA+iPT treatment for the primary outcomes. At primary endpoint, we found trends towards an intervention effect in favor of only iPT for improving gross motor function (GMFM; p=0.095, ES=1.12, 95%CI[-0.20:2.44]) and decreasing the % sedentary behavior during everyday physical activity (AG%sed; p=0.087, ES=–2.59, 95%CI[-5.58:0.39]). At 24week follow-up, we found a trend – also in favor of iPT – towards improving quality of life (DISABKIDS-smileys-proxy-version; p=0.066, ES=5.9, 95%CI[-0.40:12.20]). We found one trend in favor of BtA for improving everyday physical activity counts per minute (AGcpm; p=0.064, ES=91, 95%CI[-6:188]). Average treatment costs (including plaster and AFO) were significantly higher in BtA+iPT than in iPT (8.963 euro versus 6.182 euro, p=0.001). Conclusion We conclude that adding BtA to iPT in combined BtA+iPT treatment does not improve effectiveness (at the group level) and that adding BtA is also not cost-effective when treatment is aimed at improving gross motor function, everyday physical activity levels or quality of life.

Validation of an innovative method, based on tilt sensing, for the assessment of activity and body position

Since there is less movement during sleep than during wake, the recording of body movements by actigraphy has been used to indirectly evaluate the sleep–wake cycle. In general, most actigraphic devices are placed on the wrist and their measures are based on acceleration detection. Here, we propose an alternative way of measuring actigraphy at the level of the arm for joint evaluation of activity and body position. This method analyzes the tilt of three axes, scoring activity as the cumulative change of degrees per minute with respect to the previous sampling, and measuring arm tilt for the body position inference. In this study, subjects (N = 13) went about their daily routine for 7 days, kept daily sleep logs, wore three ambulatory monitoring devices and collected sequential saliva samples during evenings for the measurement of dim light melatonin onset (DLMO). These devices measured motor activity (arm activity, AA) and body position (P) using the tilt sensing of the arm, with acceleration (wrist acceleration, WA) and skin temperature at wrist level (WT). Cosinor, Fourier and non-parametric rhythmic analyses were performed for the different variables, and the results were compared by the ANOVA test. Linear correlations were also performed between actimetry methods (AA and WA) and WT. The AA and WA suitability for circadian phase prediction and for evaluating the sleep–wake cycle was assessed by comparison with the DLMO and sleep logs, respectively. All correlations between rhythmic parameters obtained from AA and WA were highly significant. Only parameters related to activity levels, such as mesor, RA (relative amplitude), VL5 and VM10 (value for the 5 and 10 consecutive hours of minimum and maximum activity, respectively) showed significant differences between AA and WA records. However, when a correlation analysis was performed on the phase markers acrophase, mid-time for the 10 consecutive hours of highest (M10) and mid-time for the five consecutive hours of lowest activity (L5) with DLMO, all of them showed a significant correlation for AA (R = 0.607, p = 0.028; R = 0.582, p = 0.037; R = 0.620, p = 0.031, respectively), while for WA, only acrophase did (R = 0.621, p = 0.031). Regarding sleep detection, WA showed higher specificity than AA (0.95 ± 0.01 versus 0.86 ± 0.02), while the agreement rate and sensitivity were higher for AA (0.76 ± 0.02 versus 0.66 ± 0.02 and 0.71 ± 0.03 versus 0.53 ± 0.03, respectively). Cohen’s kappa coefficient also presented the highest values for AA (0.49 ± 0.04) and AP (0.64 ± 0.04), followed by WT (0.45 ± 0.06) and WA (0.37 ± 0.04). The findings demonstrate that this alternative actigraphy method (AA), based on tilt sensing of the arm, can be used to reliably evaluate the activity and sleep–wake rhythm, since it presents a higher agreement rate and sensitivity for detecting sleep, at the same time allows the detection of body position and improves circadian phase assessment compared to the classical actigraphic method based on wrist acceleration.

Advances in the Real-time Documentation of Psychosis and Suicidal Ideation

Clinical interviews are typically used in the assessment psychosis and related clinical symptoms. However, these measures are limited by recall bias and averaging, and thus important information is lost. Ambulatory real-time monitoring devices have the advantage of providing detailed and sensitive information about symptoms. This can provide valuable information about change and fluctuations in symptoms across time. Suicide represents a substantial problem in psychiatry, but little is known about the immediate triggers of suicidal ideation. Psychological theory suggests that the instability, in addition to the intensity, of depressed mood may be an important risk factor for the development of suicidal ideation. Mobile phone-based assessments may allow for a more accurate measure of suicidality and mood across time. In this presentation, a new smart phone software application (ClinTouch) for the assessment of psychotic and related symptoms will be described. Research investigating the feasibility, acceptability, and limitations of mobile-phone based assessment will be discussed in relation to people with psychosis. Mobile phone-based research investigating the short-term predictors of thoughts about self-injury will also be considered. The talk will finish with an outline of how mobile-based assessments could be applied in clinical settings.

Exposure to Racial Discrimination and Ambulatory Blood Pressure in Women with Type 2 Diabetes.

Diabetes is the only disorder in which women's risk for heart disease exceeds men's. Elevated blood pressure (BP) increases cardiovascular risk in people with type 2 diabetes. Racial discrimination and neuroticism are both associated with BP levels but have not been examined in concert. This study investigated self-reported racial discrimination, neuroticism and ambulatory BP in women with type 2 diabetes. Thirty-nine Black and 38 White women completed a race-neutral version of the Schedule of Racist Events; BP was evaluated using ambulatory monitoring devices. Actigraphy and diaries were used to document times of sleep and wakefulness. Racial discrimination interacted with neuroticism to predict systolic and diastolic BP both while awake and during sleep, after adjustment for covariates. For each, the influence of racist events was stronger at lower levels of neuroticism. Racial discrimination is associated with higher levels of 24-h BP in diabetic women who are low in neuroticism. Copyright © 2015 John Wiley & Sons, Ltd.

Abstract 15844: Plasma Parathyroid Hormone is Independently Related to 24-Hour Pulse Wave Velocity in Patients With Primary Hyperparathyroidism - Insights fFom The EPATH Study

Introduction: Accumulating evidence indicated that high parathyroid hormone (PTH) is associated with increased cardiovascular risk. The impact of PTH on vascular structure and function is, however, still unclear. We evaluated the relationship between pulse wave velocity (PWV) as a novel index of arterial stiffness and circulating levels of PTH in patients with PTH-excess (primary hyperparathyroidism (pHPT)). Methods and Results: We analyzed baseline data of the ongoing randomized, double-blind, placebo-controlled “Effect of Eplerenone on Parathyroid Hormone Levels in Patients with Primary Hyperparathyroidism” (EPATH) study. Inclusion criteria were age of at least 18 years and a diagnosis of pHPT according to international guidelines. Standardized blood sampling was performed after an overnight fast and 24h PWV was measured by a validated non-invasive device for ambulatory hemodynamic monitoring (Mobil O Graph, I.E.M., Stolberg, Germany). Our analysis comprised 92 pHPT patients with a mean age of 68.5 +/- 9.7 years (71 % females) and a median PTH of 102 (IQR 81 - 132) pg/ml. Mean 24h PWV was 9.8 +/- 1.8 m/s, mean daytime and mean nighttime PWV were 10.0 +/- 1.7 m/s and 9.6 +/- 1.8 m/s, respectively. In multivariate linear regression analyses adjusted for age, sex, body mass index, smoking status, mean systolic and mean diastolic 24h blood pressure, antihypertensive medication, type 2 diabetes, 25-hydroxyvitamin D, serum calcium, intake of cinacalcet and fasting serum cholesterol PTH emerged as a strong predictor of mean 24h PWV (ß=0.30, p=0.012), daytime PWV and nighttime PWV (ß=0.30, p=0.011 and ß=0.30, p=0.019, respectively). Conclusion: In a selective cohort of patients with pHPT plasma PTH was strongly related to 24h PWV. These data strengthen the notion that PTH may impact on vascular function. Interventional and mechanistic trials are needed to evaluate modulatory effects on vasculature in patients with high PTH.

Direct Comparison of Three Commercially Available Devices for Voice Ambulatory Monitoring and Biofeedback

Purpose: To provide a direct comparison of three commercially available devices for voice ambulatory monitoring and biofeedback to assist voice clinicians and researchers in choosing the device that best meets their needs. Methods: The Ambulatory Phonation Monitor (APM), VocaLog, and VoxLog were descriptively compared regarding cost, availability, physical characteristics, and operational features; and quantitatively compared regarding measures of loudness (dB sound pressure level [SPL]), pitch (fundamental frequency – F0), and phonation time. The quantitative comparison used simultaneous registrations acquired during a 90-minute lecture which also included a Smartphone-based system designed to capture the raw voice signal as a reference. Results: Differences regarding cost, physical characteristics, and operational features could influence device choice. All three devices register SPL and phonation time, and also biofeedback based on SPL. Furthermore, the APM and VoxLog provide monitoring and biofeedback for F0 with the associated capability of providing additional measures related to vocal dose. All devices produced comparable results for common measures, except for the overestimation of phonation time by the VocaLog. Conclusions: The cost, operational features, and performance characteristics of the three commercially available devices for voice ambulatory monitoring and biofeedback differ in ways that can significantly impact decisions about which one is best suited for a particular application.

Precordial electrode placement for optimal ECG monitoring: Implications for ambulatory monitor devices and event recorders

IntroductionDetection of QRS complexes, P-waves and atrial fibrillation f-waves in electrocardiographic (ECG) signals is critical for the correct diagnosis of arrhythmias. We aimed to find the best bipolar lead (BL) with the highest signal amplitude and shortest inter-electrode spacing. MethodsECG signals (120seconds) were recorded in 36 patients with 16 precordial electrodes placed in a standardized pattern. An average signal was analysed for each of 120 possible BLs obtained by calculating the difference between pairs of unipolar leads. Peak-to-peak amplitudes of QRS waves (50ms around R-peak) and P waves (270–70ms before R-peak) were calculated. For patients with atrial fibrillation, power of the fibrillatory (f) wave was used instead. Maximum values at each distance were considered and differentiation analysis was performed based on incremental changes (amplitude to distance). ResultsThere was a significant correlation between distance and QRS-amplitude (r=0.78, p<0.001), P-wave amplitude (r=0.60, p<0.01) and f-wave power (r=0.79, p<0.001). The range of values was: QRS-amplitude 0.7–2.33mV, P-wave amplitude 0.07–0.18mV, and f-wave power 0.55–2.12mV2/s. The maximum value for the shortest distance was on a heart-aligned axis over the left ventricle for the QRS complex (1.9mV at 8.7cm) and over the atria for the P-wave (0.98mV) and f-waves (1.45mV2/s at 8cm, respectively). ConclusionThere is a strong positive correlation between electrode distance and ECG signal-amplitude. Distance of 8cm on a heart-aligned axis and over the relevant heart-chamber provides the highest signal amplitude for the shortest distance. These findings are essential for the design and use of ambulatory monitoring devices.

Prof. Walter McNicholas: sleep apnea-a disease calling for attention.

Professor Walter McNicholas,MD, FRCPI, FRCPC, FCCP is Newman Clinical Research Professor at University College Dublin (UCD), Director of the Pulmonary and Sleep Disorders Unit and Consultant Respiratory Physician at St. Vincent’s University Hospital, Dublin, Ireland. He is a medical graduate of UCD [1974] and has a long established track record in high level research and leadership (Figure 1). He is a leading international authority in translational research on the mechanisms and consequences of sleeprelated breathing disorders particularly sleep apnoea, and has held competitive grants from agencies such as the Health Research Board (Ireland) on a continuous basis for close to 30 years. His research interests include the pathophysiology, treatment and outcomes of sleep apnoea syndrome, the cardiovascular and metabolic consequences of the disorder, basic cell and molecular mechanisms and consequences of intermittent hypoxia, in addition to sleep disturbances in COPD and other chronic respiratory disorders. He is also closely involved in the evaluation of novel ambulatory monitoring devices for sleep disorders. He is a past Associate Editor of the European Respiratory Journal, and has published over 170 papers in Pub-Med listed Journals (h-index in 2013 of 36), in addition to more than 30 book chapters, and has edited three textbooks on breathing disorders during sleep.

An innovative method for evaluating activity rest pattern based on position changes

Since there is less movement during sleep than during wake, actigraphy permits to indirectly evaluate the sleep-wake cycle. In general, actigraphs are placed on the wrist and based on acceleration. In this validation study, we propose an alternative way of actigraphy at the level of the arm and expressed as change of degrees per minute. Its accuracy for phase prediction and for evaluating the sleep-wake cycle is assessed by comparing with the DLMO and sleep logs, respectively. In this study, subjects (N = 13) went about their daily routine for 7 days, kept daily sleep logs and wore ambulatory monitoring devices. These devices measured skin temperature at wrist level (WT), motor activity (Arm Activity, AA) and body position (P) on the arm and acceleration at wrist level (Wrist Acceleration, WA). Cosinor, non parametric and Fourier analysis were performed using AA and WA methods, and the results were compared by ANOVA test. Linear correlations were also performed between both methods and WT. DLMO was used to compare and correlate with estimated phase markers. Only mesor, RA (relative amplitude), VL5 and VM10 (value for the five and ten consecutive hours of lower and maximum activity, respectively) showed significant differences when estimated by both methods. The remaining parameters were not significantly different between both methods and all correlations between AA and WA were high. However, when phase markers were correlated with DLMO, acrophase, M10 and L5 (timing for the ten and five consecutive hours of highest and lowest activity, respectively) for AA showed a high correlation, while for WA, only acrophase did. Regarding sleep detection, WA showed higher specificity than AA, while the agreement rate and sensitivity were higher for AA. An alternative actigraphy method (AA) can be used to evaluate more accurately sleep-wake and motor activity-rest rhythm than conventional actigraphy, since this alternative is more sensitive and presents higher agreement rate for detecting sleep. Besides, it estimates better the phase according to its correlation with the “gold standard” for phase detection: DLMO. Study supported by Instituto de Salud Carlos III, RETICEF (RD12/0043/0011), MINECO (BFU 2010-21945-C02-01 and IPT-2011-0833-900000) with FEDER cofunding to JAM, and a research fellowship to MABC (FPU2009-1051). We thank Stockgrand Ltd. for melatonin assay reagents. DJ Skene is a Royal Society Wolfson Research Merit Award holder.

Circadian Time Organization of Professional Firemen: Desynchronization—Tau Differing from 24.0 Hours—Documented by Longitudinal Self-assessment of 16 Variables

*This work is dedicated to the memories of Drs. Israel Ashkenazi and Erhard Haus, outstanding pioneers of medical chronobiology, dear colleagues, and distinguished gentlemen of exceptional human qualities.We investigated the circadian synchronization/desynchronization (by field-study assessment of differences in period, τ, of 16 coexisting and well-documented rhythms) of 30 healthy firemen (FM) exposed to irregular, difficult, and stressful nocturnal work hours who demonstrated excellent clinical tolerance (allochronism). Three groups of FM were studied (A = 12 FM on 24-h duty at the fire station; B = 9 FM on 24-h duty at the emergency call center; C = 9 day-shift administrative FM) of mostly comparable average age, body mass index, career duration, chronotype—morningness/eveningness, and trait of field dependence/independence. The self-assessed 16 circadian rhythms were (i) physiological ones of sleep-wake (sleep log), activity-rest (actography), body temperature (internal transmitter pill probe), right- and left-hand grip strength (hand dynamometer), systolic and diastolic blood pressure (BP) plus heart rate (ambulatory BP monitoring device); (ii) psychological ones (visual analog self-rating scales) of sleepiness, fatigue, fitness for work, and capacity to cope with aggressive social behavior; and (iii) cognitive ones of eye-hand skill and letter cancellation, entailing performance speed (tasks completed/unit time) and accuracy (errors). Data (4–6 time points/24 h; 2 591 480 values in total) were gathered continuously throughout two 8-d spans, one in winter 2010–2011 and one in summer 2011. Each of the resulting 938 unequal-interval time series was analyzed by a special power spectrum analysis to objectively determine the prominent τ. The desynchronization ratio (DR: number of study variables with τ = 24.0 h/number of study variables × 100) served to ascertain the strength/weakness of each rhythm per individual, group, and season. The field study confirmed, independent of group and season, coexistence of rather strong and weak circadian oscillators. Interindividual differences in DR were detected between groups and seasons (χ2, correlation tests, analysis of variance [ANOVA]). Moreover, in each group, both in winter and summer, a normal distribution was observed in the number of FM with rhythms with τ = 24.0 h, e.g., ranging from 5/16 (large desynchronization) to 16/16 (no desynchronization). Such a normal distribution with intraindividual stability over time (i.e., seasons) is consistent with the hypothesis of an inherited origin of a differential propensity to circadian desynchronization and which is supported by the distribution of τs in winter and summer following the Dian-Circadian Genetic Model, i.e., with τ = 24.0 h, τ = 24.0 h + n(0.8 h), and τ = 24.0 h − n(0.8 h).

Abstract 315: Feasibility of outpatient ambulatory ECG monitoring to screen for silent atrial fibrillation: Pilot Findings from Screening Trial for Undiagnosed Atrial Fibrillation (STUDY-AF)

INTRODUCTION: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, accounting for up to one in five strokes. Identification of silent AF could reduce the total burden of stroke, particularly with newer, low-cost noninvasive methods of screening. We therefore performed a pilot study of ambulatory ECG monitoring to screen for AF. METHODS: We performed a prospective screening study by enrolling patients from May 2012 to January 2013 in outpatient clinics for cardiology, echocardiography, and stress testing at the VA Palo Alto Health Care System. Patient inclusion criteria were age ≥ 55 years and at least two of the following risk factors: coronary disease, congestive heart failure (CHF), hypertension, diabetes, and sleep apnea. We excluded patients with 1) a history of AF, supraventricular tachycardia, stroke, transient ischemic attack, systemic embolism, implantable pacemaker or defibrillator; 2) palpitations or syncope in the prior year. All patients received a small, wearable patch-based ambulatory ECG monitoring device (Zio® Patch, iRhythm Inc., San Francisco, CA) for up to two weeks of uninterrupted monitoring. The primary outcome was proportion of patients with AF. Secondary outcomes were prevalence of sustained and non-sustained ventricular tachycardia (NSVT) and supraventricular tachycardia (SVT). RESULTS: Among 57 patients (age 68 ± 7.4 years, 0% women), 53 (93%) completed ambulatory monitoring. The highest sites of enrollment were in cardiology clinic (47%) and echocardiography (46%). Atrial fibrillation was detected in three subjects (5.7%), who had a mean AF Burden of 4.2%. Common asymptomatic arrhythmias detected were SVT of ≥ 4 beats (N=37; 70%), ≥ 8 beats (N=24; 45%), and ≥ 60 seconds (N=4, 7.5%). Asymptomatic NSVT of ≥ 4 beats (N=16; 30%) and ≥ 8 beats (N=5, 9.4%) were also detected. CONCLUSION: Ambulatory screening of asymptomatic arrhythmias using the Zio® Patch is feasible; however the diagnostic yield for silent AF may be low, even among patients with established AF risk factors. Our study found a high prevalence of incidental asymptomatic SVT and NSVT. A larger trial with more targeted enrollment may be required to demonstrate the value of screening for AF. The impact of detecting incidental NSVT or SVT, which themselves could prompt evaluation and may be relevant to development of AF, requires further investigation.

Feasibility of Clinical Hypnosis For The Treatment of Parkinson's Disease: A Case Study

Parkinson's disease is a severe neurodegenerative disorder with a prevalence rate of approximately 1.6% in elderly Americans. This case study reports on a 51-year-old male Parkinson's patient who received 3 weekly sessions of a hypnosis intervention, as well as instruction in self-hypnosis. Actigraphy was used to assess rest-tremor severity. Results revealed a 94% reduction in rest tremors following treatment. Self-reported levels of anxiety, depression, sleep quality, pain, stiffness, libido, and quality of life also showed improvements. The patient reported a high level of satisfaction with treatment. These findings suggest clinical hypnosis is potentially feasible and beneficial treatment for some Parkinson's symptoms. Further investigation with diverse samples and an ambulatory monitoring device is warranted.

Security mechanism for a wireless-sensor-network-based healthcare monitoring system

Recently, with the help of remote continuous healthcare monitoring technique, elderly people with chronic medical conditions can receive therapeutic service at home or at local community without going to hospitals. Wireless sensor networks promise to revolutionise the healthcare model by allowing inexpensive, non-invasive, continuous and ambulatory healthcare monitoring devices with almost real-time updates of medical records via the Intranet/Internet. The medical data of an individual is very personal, sensitive and should be kept in a reliable and authorised entity. However, the vital personal signals transmitting in the networks cannot be prohibited to be eavesdropped during the wireless communications. Worse still, the adversary could even actively modify, inject or spoof the private vital medical data. To address the issues of system security, a hybrid key management based on elliptic curve cryptography is proposed to protect sensitive data in these stringent resource-constrained devices. In order to protect data, two modified Feistel algorithms are introduced and compared with data encryption standard (DES). At the same time, a healthcare monitoring prototype has been implemented for testing the security mechanisms by using blood oxygen level (SpO2) physiological sensor module and MICAz nodes.

087 Links Between Sleep Disordered Breathing and the Type of Acute Aortic Dissection in the Acute Phase: Differences in Patent Versus Thrombosed False Lumen

Sleep disordered breathing (SDB) has been closely linked to hypertension, which is a major risk factor for aortic dissection (AD). The impact of SDB to AD has not been revealed. We enrolled 60 consecutive AD patients who admitted to the division of Cardiology. We analyzed 23 subjects who were evaluated by an ambulatory polygraphic monitoring device within one month from the onset, in the aspect of SDB parameters' correlation with type and size of AD, and hemodynamics on arrival. The patent false lumen group (n = 10) showed significantly higher apnea-hypopnea index (AHI; p < 0.05), lower average percutaneous oxygen saturation (SpO2; p < 0.05) and significantly higher systolic blood pressure (BP) on arrival (p < 0.05) compared with those in thrombosed group. Howeveer, there found no significant correlations between AHI and AAD diameter. Systolic BP on arrival showed statistically significant correlations with AHI (r = 0.457, p < 0.05), central apnea index (r = 0.451, p < 0.05) and the minimum SpO2 (r = −0.537, p = 0.01), which suggested severe SDB would relate to elevated high systolic BP on arrival. The present study revealed that more severe SDB and hypoxia state existed in the patent false lumen group, and further higher AHI were associated with elevated systolic BP on arrival. The presence of activated sympathetic activity in catastrophic state of AD with high systolic SB might relate to appearance of central sleep apnea in acute phase of AD.

An Improved Method for Estimating Human Circadian Phase Derived From Multichannel Ambulatory Monitoring and Artificial Neural Networks

Recently, we developed a novel method for estimating human circadian phase with noninvasive ambulatory measurements combined with subject-independent multiple regression models and a curve-fitting approach. With this, we were able to estimate circadian phase under real-life conditions with low subject burden, i.e., without need of constant routine (CR) laboratory conditions, and without measuring standard circadian markers, such as core body temperature (CBT) or pineal hormone melatonin rhythms. The precision of ambulatory-derived estimated circadian phase was within an error of 12 ± 41 min (mean ± SD) in comparison to melatonin phase during a CR protocol. The physiological measures could be reduced to a triple combination: skin temperatures, irradiance in the blue spectral band of ambient light, and motion acceleration. Here, we present a nonlinear regression model approach based on artificial neural networks for a larger data set (25 healthy young males), including both the original data and additional data collected in the same protocol and using the same equipment. Throughout our validation study, subjects wore multichannel ambulatory monitoring devices and went about their daily routine for 1 wk. The devices collected a large number of physiological, behavioral, and environmental variables, including CBT, skin temperatures, cardiovascular and respiratory functions, movement/posture, ambient temperature, spectral composition and intensity of light perceived at eye level, and sleep logs. After the ambulatory phase, study volunteers underwent a 32-h CR protocol in the laboratory for measuring unmasked circadian phase (i.e., “midpoint” of the nighttime melatonin rhythm). To overcome the complex masking effects of many different confounding variables during ambulatory measurements, neural network–based nonlinear regression techniques were applied in combination with the cross-validation approach to subject-independent prediction of circadian phase. The most accurate estimate of circadian phase with a prediction error of −3 ± 23 min (mean ± SD) was achieved using only two types of the measured variables: skin temperatures and irradiance for ambient light in the blue spectral band. Compared to our previous linear multiple regression modeling approach, motion acceleration data can be excluded and prediction accuracy, nevertheless, improved. Neural network regression showed statistically significant improvement of variance of prediction error over traditional approaches in determining circadian phase based on single predictors (CBT, motion acceleration, or sleep logs), even though none of these variables was included as predictor. We, therefore, have identified two sets of noninvasive measures that, combined with the prediction model, can provide researchers and clinicians with a precise measure of internal time, in spite of the masking effects of daily behavior. This method, here validated in healthy young men, requires testing in a clinical or shiftwork population suffering from circadian sleep-wake disorders. (Author correspondence: vitaliy.kolodyazhniy@sbg.ac.at)

Links between sleep disordered breathing, coronary atherosclerotic burden, and cardiac biomarkers in patients with stable coronary artery disease

Sleep disordered breathing (SDB) is highly prevalent in patients with cardiovascular disease, although it is not clear whether SDB has any link to coronary atherosclerotic burden in patients with stable coronary artery disease (CAD). This study sought to analyze the links between SDB, coronary atherosclerotic burden, and cardiac biomarkers in stable CAD patients. We studied 83 consecutive patients who underwent coronary angiography or scheduled percutaneous coronary intervention. SDB was evaluated by an ambulatory polysomnographic monitoring device. Coronary atherosclerotic burden was evaluated by the Gensini score, and myocardial stress/injury were assessed by measuring plasma levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high sensitivity troponin T (hs-TnT). Patients with an apnea hypopnea index (AHI)≧15 events/h (n=32) showed significantly higher Gensini score (35.7±38.0 vs 20.1±19.7, p=0.033) than those with AHI<15. The higher AHI group showed significantly higher NT-proBNP (275.8±402.6 pg/ml vs 131.9±146.3 pg/ml, p=0.047) and hs-TnT levels (0.011±0.005 ng/ml vs 0.008±0.003 ng/ml, p=0.015). Furthermore it was revealed that AHI significantly correlated with the Gensini score (r=0.253, p=0.036), NT-proBNP (r=0.266, p=0.027), and hs-TnT (r=0.274, p=0.023), and multiple stepwise linear regression analysis revealed that AHI (β=0.257, p=0.029) and history of smoking (β=0.244, p=0.038) were independently correlated with Gensini score among clinical and SDB-related parameters. Severity of SDB has a significant link to the severity of coronary atherosclerotic burden, which also reflected elevated NT-proBNP and hs-TnT as silent myocardial ischemia and minute myocardial injury even in stable CAD patients.

The magnitude and duration of post-exercise hypotension after land and water exercises

The objective of the study was to determine and compare the magnitude and duration of post-exercise hypotension (PEH) during free-living conditions after an acute session of concurrent water and land exercise in individuals with prehypertension and hypertension. Twenty-one men and women (aged 52±10years) volunteered for the study. Participants completed a no exercise control session, a water exercise session and a land exercise session in random order. After all three sessions, participants underwent 24-h monitoring using an Ergoscan ambulatory BP monitoring device. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were monitored to determine changes from resting values after each session and to compare the PEH responses between land and water exercises. During daytime, both land and water exercises resulted in significantly lower SBP (12.7 and 11.3mmHg) compared to the control session (2.3mmHg). The PEH response lasted for 24h after land exercise and 9h after water exercise. There was no difference in the daytime DBP for the three treatments (P>0.05). Although all three groups showed significant reductions during nighttime, both exercise treatments showed greater nocturnal falls in BP than the control treatment. This is the first study to show that the magnitude of the PEH response is similar for land and water exercises, although the duration of PEH may be longer for land exercise. These results suggest that water exercise is a safe alternative exercise modality for individuals with suspected and known hypertension.

Validation of A&amp;D TM-2430 upper-arm blood pressure monitor for ambulatory blood pressure monitoring in children and adolescents, according to the British Hypertension Society protocol

The A&D TM-2430 ambulatory blood pressure (BP) monitor has been validated in adults but not in a young population. We sought to validate the device monitoring in children and adolescents, according to the British Hypertension Society (BHS) protocol. The A&D TM-2430 is an automated oscillometric upper-arm device for ambulatory BP monitoring. Nine consecutive measurements were taken in 61 children (mean age, 9.8 years; range, 5-15 years) according to the BHS criteria. Overseen by an independent supervisor, measurements were recorded by two observers blinded from each other's readings and from the device readings. The mean difference ± SD between the observers and device measurements was 0.73 ± 1.64 mmHg for systolic blood pressure (SBP) and -1.23 ± 1.65 mmHg for diastolic blood pressure (DBP), respectively, with an interobserver difference of 4 mmHg. The cumulative percentages of differences within 5, 10, and 15 mmHg were 89, 95, and 98% for SBP and 67, 88, and 98% for DBP. The device achieved a grade A rating for SBP and a B grade for DBP. The A&D TM-2430 upper-arm BP monitor has fulfilled the required BHS standards and can be recommended for measuring ambulatory BP in children and adolescent populations.