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BACKGROUND: Finger plethysmography derived stroke volumes are frequently measured during tilt table testing. There are two algorithms to determine stroke volumes: Modelflow and Nexfin CO Trek. Most tilt studies used Modelflow, while there are differences between the two algorithms. OBJECTIVE: To compare stroke volume indices by Nexfin CO Trek (SVINexfinCOTrek) with suprasternal Doppler derived SVI (SVIDoppler) in healthy controls (HC) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients during tilt testing. These patients may have a large SVI decrease during the tilt enabling a large range of SVI to be studied. METHODS: One hundred and fifty-four patients and 39 HC with a normal tilt test were included. Supine and end-tilt SVIDoppler and SVINexfinCOTrek were compared using the Bland-Altman analysis. Also, the effect of calibrating supine SVINexfinCOTrek to SVIDoppler was studied. RESULTS: Supine and end-tilt SVINexfinCOTrek were significantly higher than SVIDoppler: both P< 0.005. Bias, limits of agreement, and percent error (PE) were high with PE’s between 37 and 43%. The calibration procedure resulted in an acceptable variance with a PE of 29%. CONCLUSIONS: SVINexfinCOTrek overestimates stroke volumes compared to SVIDoppler, leading to high PE’s. Calibration reduced variance to an acceptable level, allowing SVINexfinCOTrek to be used for assessment of SVI changes during tilt testing.

Finger plethysmography is a well-known technique for the acquisition of arterial pulse waveforms in the field of cardiology. The technique involves the acquisition of the volumetric variation of the finger due to pulsatile flow of blood in ulnar artery, to obtain the arterial pulse waveform of the subject. Conventionally, finger plethysmography is carried out by pulse-oximetry method which evaluates the blood flow using the oxygen saturation levels in blood. Though this method is widely used, the data acquired from this method is not the actual pulse pressure experienced by the arterial walls. Therefore, in the present work, a novel, non-invasive Fiber Bragg Grating based arterial pulse acquisition device employing finger Plethysmographic technique is designed and developed. The developed Fiber Bragg Grating Plethysmographic Pulse Recorder (FBGPPR) can acquire the volumetric variations of the finger on a beat-to-beat basis, which represents the arterial pulse waveform. Further, Pulse Transit Time (PTT) evaluation is also illustrated employing FBGPPR and an electronic stethoscope wherein both the devices are triggered simultaneously. Furthermore, the acquired pulse waveforms are analyzed to obtain the accelerated pulse plethysmograph (APG) which is noteworthy to observe the minute inflections and vital features of the pulse waveform.

Pain is often mismanaged due to incorrect assessment of pain level. Currently, pain is evaluated with subjective methods only, such as pain questionnaires. It may lead to erroneous evaluation of pain level. For this reason, there is a need for objective pain evaluation. The aim of this study is to test different neural network architectures and different types of inputs derived from finger plethysmography to evaluate which type of network and input type is most suitable for objective pain detection. Photoplethysmogram signals were filtered, segmented into heartbeat pulses, and normalized in amplitude and duration. The fifty-three signal intensity and fifteen time-domain features were extracted from the pre-processed photoplethysmogram signal. Three different neural network architectures were employed with ten different types of input. Results showed that feature-based models performed better than signal-based models. All three neural networks architectures achieved a mean accuracy of 0.85 for feature-based models and 0.76 for signal-based models. Multi-layer perception neural network with 12-heartbeats averaged showed the best performance with an accuracy of 0.92. Feature-based approach and multi-layer perception neural network showed the highest accuracy, specificity, and sensitivity for pain recognition. Additional post-processing could increase model accuracy and may be used in future research.

Aging is associated with reductions in endothelial function, observations primarily reported using brachial artery ultrasound. There is growing interest in the use of peripheral artery tonometry (PAT) of microvessels in the fingertip to assess endothelial function because it is less technically demanding and has a high sensitivity and specificity for assessing coronary endothelial function. Moreover, similar to brachial artery flow-mediated dilation (FMD), PAT predicts cardiovascular disease outcomes. However, the relationship between PAT and FMD have yet to be examined in the context of aging. To address this question, reactive hyperemic index (RHI) using EndoPAT and FMD using brachial artery ultrasound were assessed after 5 min of forearm ischemia in 20 younger (18–40 yr old; 29 ± 4 yr) and 20 older (60–75 yr old; 65 ± 4 yr) healthy adult men. Higher values of both FMD and RHI indicate better endothelial function. Endothelial function assessed via brachial artery FMD was lower in older (4.8 ± 2.1%), compared with younger (7.5 ± 1.6%) men (P < 0.001). In contrast, the RHI assessed via PAT was greater in older (2.2 ± 0.6), compared with younger (1.8 ± 0.5) men (P = 0.014). FMD and RHI were not correlated (r = –0.15; P = 0.35). We conclude that PAT may not be an appropriate measure to evaluate age-associated changes in endothelial function. NEW & NOTEWORTHY Microvessel endothelial function assessed via finger plethysmography may not reflect age-associated reductions in large artery endothelial function assessed via brachial artery flow-mediated dilation.

SummaryPurpose Blood pressure (BP) is commonly assessed by brachial oscillometry in clinical practice, whereas in physiological studies, finger plethysmography is often employed. This study assessed the limits of agreement between BP metrics obtained from each device. Methods In 96 participants, we simultaneously recorded BP by brachial oscillometry (BP+; Uscom, Sydney, NSW, Australia) and finger plethysmography (Finometer MIDI, MLE1054-V; Finapres Medical Systems B.V., Amsterdam, the Netherlands). Agreement between the two devices was assessed by correlation and Bland–Altman analysis. We assessed average BP differences between the two devices using the criteria of the Association for the Advancement of Medical Instruments (AAMI), which require systolic and diastolic BP differences to be within ≤5 ± 8 (mean ± SD). Results Bland–Altman analysis showed wide limits of agreement (±~17 mmHg or greater) between finger-derived brachial and oscillometric BP. Both systolic and mean BP exhibited positive proportional biases (both P

In recent years, video plethysmography (VPG) which is pulse wave derived from the skin video image has attracted attention as a non-contact heart rate measurement technique. In this study, we propose an extraction method of VPG which can be used for arterial pulse waveform analysis. The extraction algorithm is based on periodic component analysis. The value of the second derivative analysis of palm VPG derived by proposed method had correlation with that of finger plethysmography (PPG). This results indicate the possibility of the non-contact evaluation of peripheral vascular function by VPG.

Endothelial function has diagnostic, prognostic and therapeutic significance. A number of non-invasive techniques were introduced for its assessment, including flow-mediated dilation (FMD), finger plethysmography (RH-PAT) and digital thermal monitoring (DTM). All these methods can be performed simultaneously. In addition, various methods for measuring arterial wall stiffness are available such as: pulse wave analysis (PWA), pulse wave velocity (PWV), pulse contour analysis (PCA) and carotid wall distensibility coefficient (DC). Finally, carotid intima-media thickness (cIMT) and ankle brachial index (ABI) are used as surrogate read-outs of atherosclerosis. Here, we briefly describe the advantages, limitations and interrelationships of various methods used for the assessment of endothelial function, arterial stiffness, and present the concept of an integrated evaluation of vascular health based on multiple methods. This strategy may be useful to stratify cardiovascular risk and represents a step towards multiparametric assessment of endothelium for effective endothelium-guided therapy in patients with cardiovascular diseases.

A major symptom of hand-arm vibration syndrome is a secondary Raynaud’s phenomenon—vibration white finger (VWF)—which results from a vasospasm of the digital arteries caused by work with vibration devices leading to occupational disease. Pharmacotherapy of VWF is often ineffective or has adverse effects. The aim of this work was to verify the influence of inhalation of partially ionized oxygen (O2•−) on peripheral blood vessels in the hands of patients with VWF. Ninety one (91)patients with VWF underwent four-finger adsorption plethysmography, and the pulse wave amplitude was recorded expressed in numeric parameters—called the native record. Next, a cold water test was conducted following with second plethysmography. The patients were divided in to the three groups. First and second inhaled 20-min of ionized oxygen O2•− or oxygen O2 respectively. Thirth group was control without treatment. All three groups a follow-up third plethysmography—the post-therapy record. Changes in the pulse wave amplitudes were evaluated. Inpatients group inhaling O2•− a modest increase of pulse wave amplitude was observed compared to the native record, patients inhaling medical oxygen O2 and the control showed a undesirable decline of pulse wave amplitude in VWF fingers. Strong vasodilatation were more frequent in the group inhaling O2•− compare to O2 (p &lt, 0.05). Peripheral vasodilatation achieved by inhalation of O2•− could be used for VWF treatment without undesirable side effect in hospital as well as at home environment.

Several continuous cardiac output (CO) monitoring systems have been developed. None are ideal for use in anaesthesia or critical care. They all lack precision as shown by Bland–Altman studies. However, some provide reliable CO trending, which is useful for guiding fluid optimization protocols. The key issue is which systems are reliable, and this has not been helped by a lack of understanding of validation statistics in the literature. Recent studies suggest that none of the current intra-arterial pulse contour systems trend CO reliably. Stroke volume variability may provide a reliable alternative. Strangely, Nexfin finger plethysmography did reliably trend CO during routine surgery, but not during critical care. BioReactance also appears to trend CO acceptably, but its performance is affected by certain types of surgery that alter the pathways of electrical flux. Oesophageal Doppler is now well established for guiding goal-directed fluid regimens, and its trending of CO changes seems reliable.

Objective:Flow-mediated vasodilation (FMD) has become one of the most widely assessed parameter to analyze endothelial function. However, some techniques used to measure FMD have limitations. Recently, finger plethysmography (EndoPAT) failed to show any kind of reproducibility. A semi-automatic devi

Aims: We sought to determine the accuracy of finger plethysmography using pulse waveform analysis with brachial calibration for measurement of cardiac output during submaximal exercise by comparing it against an acetylene (C2H2) uptake technique. Methods: The study included 24 healthy volunteers (12 males, age 35 ± 8 years). Testing was performed on an upright cycle ergometer using an incremental protocol. Cardiac output measurements were performed at rest and during sub-maximal exercise using a single breath C2H2uptake technique and continuously using finger plethysmography with brachial calibration. Results: Valid results at rest and during sub-maximal exercise were achieved in 20 of 24 participants. Cardiac output at rest was 5·3 ± 1·1 and 5·2 ± 1·2 l min-1for finger plethysmography and C2H2,respectively, P = 0·712. Mean difference between techniques was -0·1 ± 0·5 l min-1. Cardiac output during submaximal exercise was 10·2 ± 2·3 and 10·3 ± 2·1 l min-1for finger plethysmography and C2H2,respectively, P = 0·898. Mean difference between techniques was 0·1 ± 1·5 l min-1. The overall correlation between finger plethysmography and C2H2data obtained during rest and exercise was r2= 0·872, P

In healthy subjects, variation in cardiovascular responses to sympathetic stimulation evoked by submaximal lower body negative pressure (LBNP) is considerable. This study addressed the question whether inter-subject variation in cardiovascular responses coincides with consistent and reproducible responses in an individual subject. In 10 healthy subjects (5 female, median age 22 years), continuous hemodynamic parameters (finger plethysmography; Nexfin, Edwards Lifesciences), and time-domain baroreflex sensitivity (BRS) were quantified during three consecutive 5-min runs of LBNP at −50 mmHg. The protocol was repeated after 1 week to establish intra-subject reproducibility. In response to LBNP, 5 subjects (3 females) showed a prominent increase in heart rate (HR; 54 ± 14%, p = 0.001) with no change in total peripheral resistance (TPR; p = 0.25) whereas the other 5 subjects (2 females) demonstrated a significant rise in TPR (7 ± 3%, p = 0.017) with a moderate increase in HR (21 ± 9%, p = 0.004). These different reflex responses coincided with differences in resting BRS (22 ± 8 vs. 11 ± 3 ms/mmHg, p = 0.049) and resting HR (57 ± 8 vs. 71 ± 12 bpm, p = 0.047) and were highly reproducible over time. In conclusion, we found distinct cardiovascular response patterns to sympathetic stimulation by LBNP in young healthy individuals. These patterns of preferential autonomic blood pressure control appeared related to resting cardiac BRS and HR and were consistent over time.

A B S T R A C T In the fight against cardiovascular diseases, preventive strategies are becoming the focus of attention. One of these strategies proposes to identify individuals who are at a high risk of developing cardiovascular disease. Endothelial dysfunction could improve patient risk stratification and the implementation of preventive strategies. In this review we focus on noninvasive techniques that have recently become available to assess endothelial function: flow-mediated vasodilation as measured by ultrasound of the brachial artery, pulse wave analysis, and finger plethysmography during postischemic hyperemia. We describe the basic principles, the main protocols to perform these techniques, and their clinical value based on the scientific evidence.

Summary Background: The aims of this study were to establish the optimum duration of blood flow occlusion to obtain maximal response and to compare the response after lower-arm and upper-arm occlusion. Methods: Pulse wave amplitude was analysed using a novel finger plethysmograph (EndoPat; Itamar). For measuring reactive hyperaemic index (RHI) induced by forearm cuff occlusion, 30 healthy subjects were examined at different days in a random order of four cuff occlusion times (1·5, 3, 5 and 8 min). RHI induced by 5 min upper-arm cuff occlusion was also measured in 20 subjects. Results: Average RHI was lower with 1·5 and 3 min forearm occlusion compared with 8 min forearm occlusion (P = 0·002 and P = 0·024). There was no significant difference between values of 5 min and 8 min forearm occlusion and between 5 min forearm and 5 min upper-arm occlusion (P = 0·1). All subjects reported less discomfort after forearm occlusion compared with upper-arm occlusion. Conclusion: Maximum response was reached after 5 min of blood flow occlusion and therefore this occlusion time is recommended. The response after forearm and upper-arm occlusion did not differ significantly. Forearm occlusion might be preferred as this caused less discomfort.

Background Finger plethysmography and thermometry are objective measures used to assess the vascular aspect of hand-arm vibration syndrome (HAVS). Research to date shows poor correlation between these tests and Stockholm Workshop Scale (SWS) vascular stage. Clinicians, researchers and compensation boards require objective means to diagnose and quantify HAVS. Aims To define the specificity and sensitivity of thermometry and plethysmography using the SWS as the reference criterion. A secondary goal was to consider cut points for the tests optimizing sensitivity and specificity. Methods A cross-sectional analysis was conducted on HAVS patients seen at an occupational medicine specialty clinic. Plethysmography and thermometry were analyzed using SWS vascular stage as the outcome variable. Logistic regression controlled for age, smoking and time since last vibration exposure and use of vasoactive medications. The sensitivity and specificity of the combined tests were calculated using varying cut points. Results A total of 139 patients consented to participate in the study. Plethysmography stage 1 or greater showed the highest sensitivity (sensitivity 94% and specificity 15%). Specificity was optimized combining plethysmography stage 3 and thermometry stage 3 (specificity 98% and sensitivity 23%). Maximal diagnostic accuracy was achieved by plethysmography alone setting the criteria for a positive test as being stage 1 or greater (70%). Conclusions Neither plethysmography nor thermometry either alone or in combination demonstrated sufficient sensitivity and specificity to serve as an objective correlate for SWS vascular stage. All combinations of plethysmography and thermometry showed a lower specificity than sensitivity indicating that the SWS may be less sensitive in detecting vascular pathology than the objective tests.

Successful treatment of cough syncope depends on the correction of various pathogenetic mechanisms among different patients. The valsalva maneuver (VM), which elicits hemodynamic responses mimicking coughs, has potential for investigating the individual pathogenesis of cough syncope. Eighteen consecutive patients suffering from cough-induced syncope were examined. All patients were asked to cough and to perform VM several times under continuous cerebral blood-flow velocity and blood pressure (BP) monitoring by transcranial Doppler and finger plethysmography. Eight patients demonstrated abnormal VM characterized by the absent BP overshoot following the relief of straining. Patients demonstrating abnormal VM had delayed BP recovery after cough (median, 16.4; range, 8.7–25.6 seconds) compared to those demonstrating normal VM (2.6, 1.3–3.8 seconds, p < 0.001). Seven of the 10 patients exhibiting normal BP overshoot during VM had stenotic arterial lesions in the cerebral or coronary circulation, whereas only one of the eight patients demonstrating absent BP overshoot had coronary artery disease (70% vs. 12.5%, p = 0.025). Other clinical profiles, body mass index, frequency of obstructive pulmonary disease and valsalva ratio did not differ between patients featuring normal and absent BP overshoot. In conclusion, the pathogenesis of cough syncope could be different between patients with normal and abnormal VM responses. Patients who had no BP overshoot during VM sustained prolonged hypotension after cough. The VM helps in discriminating among pathogenic mechanisms and guiding investigation and treatment for cough syncope patients.

We tested a simple noninvasive method for cardiac resynchronization therapy (CRT) optimization using standard finger photoplethysmography (FPPG).CRT can increase left ventricular cardiac output in patients with heart failure and ventricular conduction delay. Optimal therapy delivery depends on an appropriate AV delay. Multiple invasive and noninvasive methods have been attempted to identify patients and the best AV delay for CRT, but all suffer from a combination of high patient risk, cost, complexity, and low reproducibility.FPPG and invasive aortic pressure data were simultaneously collected from 57 heart failure patients during intrinsic rhythm alternating with very brief periods of pacing at 4 to 5 AV delays. After correcting data for artifacts, the median percentage responses for each AV delay were classified as positive, negative, or neutral compared to baseline (Wilcoxon rank test).FPPG correctly identified positive aortic pulse pressure responses with 71% sensitivity (95% CI: 60-80%) and 90% specificity (95% CI: 84-94%) and negative aortic pulse pressure responses with 57% sensitivity (95% CI: 44-69%) and 96% specificity (95% CI: 91-98%). The magnitude of FPPG changes were strongly correlated with positive aortic pulse pressure changes (R(2) = 0.73, P.0001) but less well correlated with negative aortic pulse pressure changes (R(2) = 0.43, P.0001). FPPG selected 78% of the patients having positive aortic pulse pressure changes to CRT and identified the AV delay giving maximum aortic pulse pressure change in all selected patients.FPPG can provide a simple noninvasive method for identifying significant changes in aortic pulse pressure with high specificity, including identifying patients in whom aortic pulse pressure increases with CRT and the AV delay giving the maximum aortic pulse pressure.

The aim of this work is different methods and realizations of telemetric data transfer from pulse oximeter Criticare 504 USP to computer. This device takes the plethysmographycal curve, ECG curve, saturation and beat. Plethysmography is diagnostic method, which serves for rating ofwell perfused tissue and gives information about working and reactivity of vessels. Finger plethysmography focus on acquiring records ofpulse waves during hearth action by sensor, which is located on the end of finger. In present time, the plethysmography is classic non-invasive method for examinee ofvessels, which is used in angiology and also in industrial medicine

Das obstruktive Schlafapnoesyndrom ist eine in der westlichen Welt häufige Erkrankung, die mit einem erhöhten Risiko für kardiovaskuläre Erkrankungen einhergeht. Es wird davon ausgegangen, dass durch Hypoxie, Sympathikuserhöhung und thorakalem Scherstress eine endotheliale Dysfunktion verursacht wird. Dennoch ist nicht abschließend geklärt, ob die obstruktive Schlafapnoe alleine für diese Tatsache verantwortlich sein kann oder ob ein Zusammenhang aufgrund der häufigen Komorbiditäten (arterielle Hypertonie, Diabetes mellitus oder Adipositas) lediglich so erscheinen mag. In dieser Arbeit wurde versucht, mit einer nicht-invasiven Methode die Auswirkungen des obstruktiven Schlafapnoesyndroms auf das vaskuläre Endothel zu beurteilen. Dabei wurde darauf geachtet, dass die Studienteilnehmer neben einer obstruktiven Schlafapnoe keine weiteren Erkrankungen hatten, um mögliche Fehlerquellen ausschließen. Es wurden zwei Gruppen untersucht, wobei die ausschließlich männlichen Teilnehmer zwischen 18 und 65 Jahren sein sollten und keine kardiovaskulären Nebenerkrankungen haben durften. Die OSA-Gruppe mit 38 Teilnehmern sollte einen AHI von >5/h haben (AHI: 24,00/h ± 22,4/h), die Kontrollgruppe mit 34 Teilnehmern sollte einen AHI von ≤5/h (AHI: 2,1/h ± 1,4/h). Bei jeweils gleichen Untersuchungsbedingungen erfolgte eine abendliche Messung der Endothelfunktion und der Gefäßsteifigkeit mittels Fingerplethysmographie (EndoPAT™ 2000, Itamar). Im Anschluss wurde eine mindestens 6-stündige kardiorespiratorische Polysomnographie durchgeführt, um unmittelbar nach Wecken des Probanden eine zweite EndoPAT™-Messung durchzuführen. Es herrschten stets gleiche Bedingungen für beide Gruppen, die Messmethode wurde standardisiert für jeden Probanden genau gleich durchgeführt. Mittels der EndoPAT™-Messung wurde der RHI als Parameter für die endotheliale Funktion gemessen, der Augmentationsindex wurde als Parameter für die Gefäßsteifigkeit gemessen. Die Berechnung der jeweiligen Werte erfolgte durch die geräteeigene Software (Itamar). Die Ergebnisse der Polysomnographie wurden durch medizinisch technische Assistenten nach den Richtlinien der DGSM ausgewertet und dokumentiert. Ziel der Studie war es erstens aufzuzeigen, dass Patienten mit Schlafapnoe eine schlechtere endotheliale Funktion und eine höhere Gefäßsteifigkeit haben und zweitens, dass sich diese Eigenschaften während der Nacht durch die nächtlichen Hypoxiephasen beim Patienten mit Schlafapnoe negativ auswirkt. In beiden Punkten konnten in der vorliegenden Studie keine signifikanten Unterschiede aufgezeigt werden, wenngleich Tendenzen erkennbar sind, welche die Primär- und Sekundärhypothesen stützen. Wie bereits in verschiedenen anderen Arbeiten beobachtet, zeigt sich auch in unserem Kollektiv eine Korrelation zwischen Alter und Gefäßsteifigkeit. In unserer Studie konnte ein veränderter Gefäßstatus bei Patienten mit moderater obstruktiver Schlafapnoe nicht endgültig dargestellt werden. Abschließend ist für künftige Studien zu diesem Thema ein erweitertes Kollektiv zu empfehlen. Zudem sollten die Einschlusskriterien vor allem beim Lebensalter enger gefasst werden, um eine mögliche Fehlerquelle zu eliminieren., Obstructive sleep apnea (OSA) is a very common sleep disorder in the western civilization, which carries an increased risk of developing cardiovascular diseases. It is assumed, that hypoxia, sympathetic stress levels and thoracic shear stress may contribute to the development of endothelial dysfunction. Since patients suffering from obstructive sleep apnea, commonly also suffer from other comorbidities, particularly arterial hypertension, diabetes mellitus and obesity, there is not absolute certainty, that a sleep disorder alone is responsible for a loss of endothelial function. The aim of this study was to measure the consequences of obstructive sleep apnea on the vascular endothelium with a non-invasive method. We examined two groups of male patients between the ages of 18 and 65 who did not suffer from any cardiovascular diseases. To reduce any bias, we tried to exclude patients with any comorbidities. We included 38 patients with a median apnea hypopnea index (AHI) of 22,0 ± 22,4/h in the OSA-group (AHI≥5/h), and in the control-group (AHI≤5/h) 34 patients with a median AHI of 2,1 ± 1,4/h. In similar surroundings and under similar conditions we then performed the first EndoPAT™2000 measurement, followed by a polysomnography for at least 6 hours and another EndoPAT™2000 measurement. By measuring the reactive hyperaemic index (RHI) we received a parameter for evaluating the endothelial function. The arterial stiffness was assessed by measuring the augmentation index (AI). The RHI and AI were calculated through the use of the EndoPAT™2000-software, while the polysomnography was analyzed by experienced medical staff according to the DGSM-guidelines. The primary objective of the study was to show, that patients with obstructive sleep apnea have an impaired arterial stiffness and endothelial function. Another aim was to show, that the both functions decline during the night. Despite not finding significant differences, we did however see encouraging tendencies to prove our theories. Similar to the results of other studies we could show a correlation between age and arterial stiffness. For further studies we suggest a bigger collective of a more similar background regarding age and medical history. Moreover, the OSA-group should consist of patients suffering from severe OSA.

Background: The purpose of the present paper was to clarify the etiologic and pathophysiologic bases of periventricular lucency (PVL). Methods: The relationship between PVL severity and hemodynamic variables derived by second-derivative finger plethysmography (SD-PTG) was studied. A total of 307 consecutively examined outpatients 60 years or older (mean age: 77.7 years; 149 men, 158 women) was enrolled. On the basis of brain computed tomography, PVL was classified into four grades (0–3) according to a modification of the classification of van Swieten. The grade of PVL was assessed at two points in each patient: anterior and posterior. The heights of the a, b, and d waves on the SD-PTG waveform were measured from baseline. The b/a ratio, indicating distensibility of the aorta, and the d/a ratio, indicating peripheral resistance, were calculated. Results: An anterior PVL of grade 3 had a significantly higher b/a ratio and a significantly lower d/a ratio than that of grade 0 or grade 1 (both P < 0.05). For posterior PVL, the b/a ratio and the d/a ratio were similar for all four grades. The anterior PVL grade was compared with the posterior PVL grade in individual subjects. This comparison yielded six groups: four in which PVL grade was similar (0, 1, 2 or 3) in both regions, one in which the grade for anterior PVL was higher than that for posterior PVL (predominantly anterior group), and one in which the grade for posterior PVL was higher than that for anterior PVL (predominantly posterior group). In patients with predominantly anterior PVL, the b/a ratio and incidence of lacunae were significantly higher than that in patients with predominantly posterior PVL. Conclusion: These findings indicate that the frontal white matter is susceptible to hemodynamic stress. It is suggested that decreased aortic distensibility may promote fibrohyaline thickening of the medullary arteries, increasing the risk of PVL.

We have studied an estimation of subjective stress using the finger plethysmography so far. However the measurement of the finger plethysmography makes the subjects feel suffering or physical load. This paper proposes a method via NeuroSky MindSet headset to reduce the suffering or the physical load, instead of the method using the finger plethysmography.We conducted the experiment to compare the estimations of the subjective stress via both the MindSet and the sensor of finger plethysmography. The experimental results indicated that the biosignals via MindSet could have higher potential than the finger plethysmography to estimate the subjective stress.

A B S T R A C T In the fight against cardiovascular diseases, preventive strategies are becoming the focus of attention. One of these strategies proposes to identify individuals who are at a high risk of developing cardiovascular disease. Endothelial dysfunction could improve patient risk stratification and the implementation of preventive strategies. In this review we focus on noninvasive techniques that have recently become available to assess endothelial function: flow-mediated vasodilation as measured by ultrasound of the brachial artery, pulse wave analysis, and finger plethysmography during postischemic hyperemia. We describe the basic principles, the main protocols to perform these techniques, and their clinical value based on the scientific evidence.

Sporadic data present in literature report how preterm birth and low birth weight constitute the risk factors for the development of cardiovascular diseases in later life.To assess the presence of potential alterations to endothelial function in young adults born preterm at extremely low birth weight (1000 g; ex ELBW).Thirty-two ex-ELBW subjects (10 males [M] and 22 females [F], aged 17-28 years, mean [+/- DS] 20.1 +/- 2.5 years) were compared with 32 healthy, age-matched subjects born at term (C, 9 M and 23 F).1) pathological conditions known to affect endothelial function; 2) administration of drugs known to affect endothelial function. Endothelial function was assessed by non-invasive finger plethysmography, previously validated by the US Food and Drug Administration (Endopath; Itamar Medical Ltd., Cesarea, Israel).Endothelial function was significantly reduced in ex-ELBW subjects compared to C (1.94 +/- 0.37 vs. 2.68 +/- 0.41, p0.0001). Moreover, this function correlated significantly with gestational age (r = 0.56, p0.0009) and birth weight (r = 0.63, p0.0001).The results obtained reveal a significant decrease in endothelial function of ex-ELBW subjects compared to controls, underlining a probable correlation with preterm birth and low birth weight. Taken together, these results suggest that an ELBW may underlie the onset of early circulatory dysfunction predictive of increased cardiovascular risk.

The paper aims at presenting problems and prospects of possibilities for automatic evaluation of finger plethysmography by use Fourier and wavelet transform. To these days no special proceeding exists, which could be used for the exact analysis of plethysmographycal recordings. It is why we elaborated the method which could lead to creation of the systematic method for the automatic evaluation of a plethysmographycal record. This method is also suitably completed by the use of wavelet transform which enables compression and filtration for saving disk space for data storage.

We propose the validation method and the result for spectrum analysis of finger plethysmography signal. We evaluate a period which is needed for steady-state oscillation of blood flow by adapting fourier spectrum analysis of finger plethysmography and investigate the analytic period by changing of confidence level. 7 subjects participate for experiment and 35 data are used for simulation. As a result of simulation, we estimate the minimum period for spectrum analysis and confidence levels for finger plethysmography. Moreover, comparing the existing result, we bring up the possibility of non-invasive analysis of blood pressure.

The symptomatic effects of felodipine (Plendil(R)) have been assessed in 10 patients with primary Raynaud's phenomenon in a single blind study. After 2 weeks on placebo, the patients were treated for 6 weeks with felodipine, the dose being titrated stepwise every 2 weeks, starting with 5 mg, and increasing to 10 mg and 20 mg once daily if symptoms persisted. After the drug period the patients received placebo for 2 weeks.Objective measurement by cold exposure finger plethysmography did not show any benefit of felodipine in the higher temperature range, taking 33-degrees-C as reference point. However, when using 24-degrees-C as the reference point, the area under the plethysmography versus temperature curve (AUC) for 5 mg felodipine were significantly larger than the initial placebo area. The AUC during recovery from cold exposure for the maximal accepted dose of felodipine was significantly larger than for the initial placebo period.Subjective judgement by the patients showed a significant reduction in the number of Raynaud attacks and a trend to a shorter duration of attacks with the maximal dose of felodipine. Two patients became free from attacks of Raynaud's phenomenon. Felodipine 10 mg once daily was well tolerated. It was regarded as the optimal dose to treat patients with Raynaud's symptoms.

The synchronous changes of subjective and autonomic responses to neutral and "stress' stimulation in patients with involutional depression and normal subjects were investigated. The stimuli employed were individually determined during a pretest interview and consisted of neutral, emotionally loaded and "mental task' testing periods of equal duration presented at random. GSR, heart rate and finger plethysmography measures were taken during administration of these stimuli, while the subjective anxiety experienced during the same periods of stimulation was rated by the subjects on a five-point scale. The results suggest that measures of synchrony between subjective and autonomic response systems may differentiate (1) patients from controls and (2) certain types of emotional stimuli from others in patients. Implications for further research regarding the qualitative differentiation of the arousal associated with emotional stimuli are discussed.

Eight patients with Raynaud's phenomenon were entered into a double-blind crossover study of nifedipine versus placebo, with 7 patients undergoing finger plethysmography before and after sublingual nifedipine administration. While receiving nifedipine, all patients reported decreased frequency and severity of attacks, and 4 of 5 had digital ulcer healing. Total finger blood flow increased 5 of 6 patients after treatment with sublingual nifedipine. This preliminary study indicates that nifedipine may be a useful agent for treatment of digital vasospasm.

The heated thermocouple method for continuous recording of skin blood-flow is compared qualitatively, quantitatively and technically with finger calorimetry and finger plethysmography. It is concluded that: (1) The heated thermocouple method records qualitative changes in skin blood-flow satisfactorily; it can be used as a qualitative index in experiments involving strenuous physical exertion; response to sudden change in flow is slower than venous occlusion plethysmography but faster than calorimetry. (2) The method is not reliable quantitatively; a marked, variable and unpredictable drift in baseline occurs. (3) The method is semi-automatic, but the siting of the skin applicator is time-consuming.

In an investigation of blood-pressure changes during interview, it was found that random emotional stresses were uncovered which had potent pressor effects in normal controls, in hypertensives and in neurotics. It was notable that the diastolic increases were proportionately greater than the systolic, and that those random emotional stresses on average possessed more pressor effect than a deliberately imposed physiological stress such as breath-holding. Certain individuals also showed marked pressor responses to varied stimuli such as being asked to do mental arithmetic, or the desire on micturate. All subjects showed an increase in systolic and diastolic pressures at the start of interview; in the control group this tended to level off symmetrically as the interview closed, but the hypertensive and neurotic groups showed a sustained rise of pressure and the resting levels after interview did not fall as low as the pre-interview resting values. No consistent topics were found to be pressor in effect, but it appeared that pressor responses occurred (1) with novel or “alerting” stimuli; (2) when the subject talked about herself, about illness or about her husband; (3) when the subject's verbal output increased. The heart rate tended to increase along with the blood-pressure, but subjects having higher blood-pressure levels tended to have slower heart rates. Finger plethysmography showed that peripheral vasoconstriction accompanied pressor responses, and vasodilatation occurred as blood-pressure fell. A neurotic patient with labile blood-pressure was interviewed on 24 occasions, and several unusual features are described. No constant or reliable association was discovered to exist between the temporal electro-encephalogram and the blood-pressure changes. It is concluded that two types of emotionally-caused pressor responses may exist; one which may be keyed to the life-situation and is sustained in effect over a period of hours or days or longer, and another which is more transient and may represent a non specifIc alerting reaction.

In patients with heart failure, left ventricular systolic dysfunction and prolonged QRS complex, cardiac resynchronization therapy (CRT) is a treatment method aimed at restoration of myocardial depolarization synchronicity. However, the extent of clinical and echocardiographic improvement depends on anatomical relations in individual patients, on structural changes in the heart, on intrinsic electrical activation, and on the position of pacing leads. Many parameters of CRT devices may be changed in order to tailor the function of CRT to the needs of a particular patient; the most important among them is AV and VV interval. The largest trials studying CRT used various methods for optimization of these intervals but unequivocal proof of the benefit brought by optimization is still lacking. Many methods were evaluated, most frequently based on echocardiography and intracardiac electrogram interval measurement. However, drawbacks in statistics make the studies of limited value for establishing a reference method or guidance for daily practice. Echocardiography has inherent variability of results and is highly operator dependent. Optimization based on intracardiac electrogram intervals has not proved yet to be of clear benefit above arbitrary AV interval. The most promising method is hemodynamic assessment by finger plethysmography. Measured data are highly reproducible and operator-independentA randomized multicenter double-blind study using finger plethysmography is needed to prove the value of this method and of CRT optimization in general. The measurement of information content in any data suitable for CRT optimization, analysis of reproducibility and general usage of confidence intervals may show other methods appropriate for it, too. The cooperation with a statistician is oftentimes a necessity.

A non-invasive method of measuring blood pressure in the finger continuously was developed by Penaz in 1976 [2], Since then the method has been further developed by Wesseling et al. [3] to produce an instrument which is easy to use in the clinical setting.1

An attempt was made to analyze differences in the results obtained by various kinds of finger plethysmography, such as penetration photo-electric plethysmograph (penet.-PTG), reflexion photo-electric PTG (refl.-PTG), mechanoelectric PTG (pneumo-PTG and hydro-PTG) and impedance PTG, by taking simultaneous recordings principally from the same finger tip. Comparisons of the time course (onset time and crest time) and the wave form (harmonic analysis and base line deviation) of each pulse wave were made with the standard records of the penet.-PTG depicted simultaneously. Experiments were repeated on 15 healthy adults. No significant differences were observed in the time course and wave form among the records obtained by various kinds of plethysmographs, so far as the records obtained from the finger tip were concerned, whereas appreciable differences were recognized in the time course as well as in the wave form, when the proximal phalange of the finger was involved in the plethysmograph, the whole finger cup being employed for mechanoelectric PTG, or one of the electrodes being placed at the proximal phalange for impedance PTG.