Plethysmogram Research Articles

Optimal Design to Ensure Maximum Coupling Between Magnetic Flux and Arterial Blood in a Magneto Plethysmo Gram Sensor Head

Magneto plethysmo gram (MPG), like the Photo plethysmo gram (PPG) is a signal that carries information on blood volume flow and is obtained noninvasively. Unlike PPG, MPG is obtained from a peripheral artery, such as radial, carotid or brachial. The magnetic flux required for obtaining an MPG is generated by a permanent magnet placed on the wrist surface such that the generated flux couples with the blood flow in the artery. In this work it is shown that maximum coupling of flux with the blood flow in radial artery occurs when the distance between the open end of the U shaped probe is 12 mm. In order to attain this result, first the probe is simulated using the finite element method. The distance between the pole faces is varied in steps of 1 mm. Simulation results clearly indicate that the optimal distance is 12mm. Next experiments were conducted with prototype probes of varying distances between the pole faces on 20 volunteers of different age and gender. The experimental results validate the result obtained by the simulation study.

Estimation of arterial pressure from pletismography data

Continuous blood pressure monitoring is important for the prevention and early diagnosis of cardiovascular diseases, the number of which is growing worldwide. A method for measuring blood pressure (BP) based on a plethysmography signal is one of many simple methods for non-invasive monitoring of blood pressure. The article presents a comparative analysis of blood pressure signals and plethysmograms (PG) synchronized in time, as well as their spectral features. A certain temporal structural similarity of the BP and PG signals (correspondence of time intervals, amplitudes) with a simultaneous time shift of the PG signal was revealed. It is shown how adequately one can judge blood pressure, having only the captured PG data. As the time intervals, the minute sequence of cardiac cycles was chosen. It is noted that with appropriate calibration of PG signals, it is possible to estimate the average blood pressure value for several cardiac cycles. The results obtained can be used in the diagnosis of various pathologies.

Heart Rate Measuring and Performance Evaluation from Carotid Artery and Occipital Artery According to Posture during Sleep Using Multiple Photo Plethysmo Gram (PPG) Sensor

Objectives: This paper will suggest that heart rate can be measured without motion artifacts even when the sleeping position is not constrained, but changes. Methods/Statistical Analysis: It was implement a heart rate measurement system, using the multiple Photo Plethysmo Gram (PPG) sensor and Fast Fourier Transform (FFT). And in experiments using the implemented system, it comparatively evaluates the performance of measuring heart rates at the carotid artery and the occipital artery around the neck according to changed sleeping positions against the performance of measuring heart rates at the finger. Findings: The deviations of heart rates measured at the carotid artery (1 minute: 1.07-6.21 bpm, 10 minutes: 0.57-5.18 bpm) and heart rates measured at the occipital artery (1 minute: 0.46-3.96 bpm, 10 minutes: 0.34- 5.2 bpm) from heart rate measured at the finger were found to be relatively low, with max 6.21 bpm at the carotid artery and max 5.2 bpm at the occipital artery. If heart rate had been found to be 0 or an abnormally high value, the deviation from heart rate at the finger would have shown a great difference. From this, It was found that there is almost no difference in the performance of heart-rate measurement the carotid artery and the occipital artery around the neck between the finger. Therefore, this paper suggested that it is possible to measure heart rates without noise even when sleeping positions are unconstrained and are subjected to changes. Improvements/Applications: From this, Can be measured during sleep, the unconstrained use heart rate in a variety of situations.

Arterial stiffness and heart rate variability analysis in patients with mild–moderate obstructive sleep apnoea, with and without excessive daytime sleepiness

Background: Patients with severe obstructive sleep apnoea syndrome (OSAS) show higher risk of cardiovascular disease (CV) and exhibit an increased arterial stiffness and a deregulation of autonomic nervous system (ANS) activity. Data are lacking in patients with mild-moderate OSAS. The study aimed to analyze heart rate variability (HRV) and arterial stiffness in patients with mild–moderate OSAS, with and without symptoms of excessive daytime sleepiness (EDS). Methods: Fifty-six male patients with mild–moderate OSAS [apnoea/hypopnea index (AHI) between 5 and 30 events/hour], without any CV risk factor, underwent full polysomnography (NPSG). Patients were divided into two groups according to the Epworth Sleepiness Scale (ESS), a subjective assessment of daytime sleepiness. During the first and the last 5 minutes of NPSG, in the wake stage, and overnight we have analysed arterial stiffness index (SIDVP), derived from digital plethysmogram, and heart rate variability. Results: The two groups were matched for age, body mass index (BMI) and AHI, did not show differences in terms of arterial stiffness. Patients with an ESS >10 had similar values of SIDVP compared with patients without EDS. In terms of HRV we have found a significant difference only in low frequency (LF) power at the end of the NPSG study (LF power 14,601±7,495 vs. 21,031±14,257 ms 2 , P<0.05), with no differences in the other HRV parameters. Conclusions: Patients with mild-moderate OSAS, with or without EDS, exhibit similar arterial stiffness and HRV and therefore might have a similar CV risk.

Design and Development of a Two Channel Telemedicine System for Rural Healthcare

In this work, an attempt has been made to design an Electro Cardio Gram (ECG) and Photo Plethysmo Gram (PPG) based telemedicine system for rural health care. In India as per the survey conducted by Indian Medical Society in the year 2009, it has been revealed that only 2% of the qualified doctors practice in rural areas. Also, according to the statistics taken by the World Health Organization, every year an estimated 17 million people die of various cardio vascular diseases. This paper introduces the transmission of ECG and PULSE from remote areas to the specialists’ office. The ECG and PPG signals are acquired, digitized and processed using LabVIEW for detection of heart and pulse rate. These data are transmitted using two methods namely Web publishing tool and Shared Variables. The results confirm the transfer of data with less than millisecond delay.

A Study on Effects of Waiting Period in Software Operation on the Operator's Psychophysiological State

The authors have been studying psychophysiological workload of human interface (HI) with physiological measurements and analysis. In this study, we investigated a kind of mental workload produced by user's unexpected waiting period from the request input to the termination of data processing during personal computer (PC) operation. As the experimental setting of HI, we used interactive software containing easy questions with unexpected time interval between each question. The effects of progress indicator (PI) indicating during waiting period on psychophysiological status of users were analyzed by using respiration, finger plethysmogram (PTG), heart rate (HR) and electroencephalogram (EEG) measurements. Results showed that the theta wave component of the EEG increased in the non-PI condition, even though autonomic nervous system parameters showed no significant change. Negative correlation between preference score for HI and integrated theta component percentage was observed only in non-PI condition. It is supposed that the PI was controlling theta activity coused by waiting stress in experimental condition. Utilizing physiological indices for HI assessment, this experimental method could be available to waiting stress estimation.

１日の平均歩数が加速度脈波からみた末梢循環機能に及ぼす影響について

1日の平均歩数が中高年女性の末梢循環機能に及ぼす影響について検討することを目的として行った。対象は, 平成5～7年に肥満予防教室や糖尿病予防教室等を受講した中高年女性58名であった。受講中の1日の平均歩数が8, 000歩以上であった者をA群 (61.7±6.1歳) , 7, 000歩代であった者をB群 (60.8±6.0歳) , 7, 000歩未満であった者をC群 (65.1±2.5歳) とし, 教室前後で比較を行った。末梢循環機能の評価は, 加速度脈波計を用いて右手第2指の指尖部にて測定した。得られた波形をA～Gに分類, また算出された加速度脈波形数 (APG-Index) を採用した。その結果, すべての群において教室前後で体重, BMIの低下がみられた。A群ではHDLCの増加とFBSの低下がみられ, B群では最大酸素摂取量の増加とSBP, TC, LDL-Cの低下がみられた。A・B群では, 教室後に加速度脈波の波形タイプの改善がみられ, さらに加速度脈波形数の増加もみられた。以上の結果から, 1日7, 000歩, またはそれ以上の歩行により, 中高年女性における末梢循環機能の改善が可能であることが示唆された。

Psychophysiological Correlates of Relaxation Induced by Standard Autogenic Training

Background: The present study aimed to determine the psychophysiological changes induced in subjects by standard autogenic training (AT). Physiological measurements were taken under strict experimental conditions. Methods: Thirty-one healthy students were divided randomly into two groups: the AT group and the control group. In the first session, the physiological variables were measured for all students before and after all were asked to relax in their own way. The AT group were then taught AT for 3 months, after which time the measurements were repeated. In the second session, the AT group practised the standard AT exercise, while the control group repeated their own form of simple relaxation. Electrocardiogram, plethysmogram (PTG) and blood pressure (BP) were measured while the students carried out a breathing rate of 15 cycles/min. The R-R intervals and BP were analysed by an autoregressive model for spectral analysis, and the data were compared by repeated-measures ANOVA. Results: The AT group had a significant increase in the mean R-R interval and a significant decrease in the baseline deflection of the PTG in the second session. There were no significant changes in sympathetic activity except for the change in the PTG, although low frequency amplitude of systolic BP decreased slightly. Conclusions: AT was found to induce significant changes that were independent of respiration in healthy students, although paced breathing might have operated as a mental stress. The increase in mean R-R interval and the decrease in baseline deflection of the PTG were the most robust correlates of AT.

運転と加速度脈波の変動性に関する研究

運転と加速度脈波の変動性に関する研究

The digital plethysmogram as an index of ageing grade.

In order to determine whether the digital plethysmogram (PTG) can be used as an index of ageing or not, the PTG was recorded in 89 males and 110 females in a pilot study. Of the parameters which were calculated from the PTG, up-stroke time corrected by pulse rate (SXp time) showed the strongest correlation with age. The PTG was recorded in 1066 males and 761 females. There was a significant correlation between age and SXp time in both sexes. The change of SXp time with age in the younger age group was more rapid than in the old age group. From these results, SXp time of the PTG can be used as an index of ageing, especially in the young to middle-aged group.

Individual differences in the responses to repeated bell sound bursts of heart rate and plethysmogram from the index finger.

To investigate the possible individual differences in response pattern of the autonomic functions to sound stimulation, simultaneous measurements of the heart rate (HR) and plethysmogram (PLT) from the index finger were performed when bell-sound bursts were presented irregularly as well as regularly.The subjects were 3 healthy male students, ages 19, 19 and 22 years. They were exposed to 3s long bell sound bursts (91.5dBA) presented regularly with intervals of 150s and irregularly with random from 90 to 150s in an insulated room with the background sound level under 30dBA inside. Both of the regular and irregular sessions consisted of 5 blocks of 5 exposures as above. The intervals between blocks were 5min. The irregular session was conducted one week after the regular one.ECG (chest lead, V4) records from -3 to 30s after each 3s long burst were divided into eleven 3s records, and mean HR was calculated from the mean R-R intervals included completely within each 3s record. In the same manner, mean finger-top plethysmogram amplitude for all the complete waves within each time period of 3s before, during and after each bell sound burst were calculated. However, all the responses were examined as percent changes to the pre-exposure 3 s-long values in all the cases.The results of HR responses to sounds showed such great intra- and inter-individual variations that any consistent trends like habituation (gradual decrement of responses with repetition of stimuli) could not be observed. Only in block 1 of the regular session in Subject 1, consistent and typical HR responses were found, which showed rapid tachycardia followed by bradycardia. On the other hand, PLT showed consistent and significant responses especially in the regular session as shown in the figures. Decremental process of the minimum peaks or habituation with repetitive stimulations from block 1 to 5 in the regular session was obvious in Subject 1 and 3, whereas in Subject 2, on the contrary, the minimum peaks increased with repetition of the stimulations.Thus, individual differences in response patterns of the autonomic nervous system functions were confirmed to be possible, which may cause great intra- and inter-individual variation in the autonomic functions especially when only one measurement like HR is adopted as a parameter. However, one cannot deny that a subject, who does not respond in HR to sound, may be significantly susceptible to the same sound in another aspect like peripheral circulation. Therefore, further study is needed to clarify such subtypes of the autonomic functions to investigate the physiological effects of noise as well as to use sound stimulation in a test of the autonomic functions. It should also be noted that habituation or sensitization could be significantly observed in some of the autonomic functions, only if sounds are presented regularly.

Disorders in peripheral arterial system in asymptomatic elderly: plethysmographic semiology at rest, during postural, effort and pharmacological tests.

The vascular system of 30 old asymptomatic patients (average age 62.5 years) was studied by reflection plethysmography. The plethysmogram (PTG) was recorded from the forefinger of the left hand at rest, during two postural tests (+45 degrees arm-up and -45 degrees arm-down), after physical work, and during the infusion of nitroglycerin and the beta-agonist metaproterenol. 50% of the subjects presented a normal PTG under basal conditions. However, pathological PTGs were recorded after the various tests: 23.3% with the arm-up test, 6.6% with the arm-down test, 52% with the effort test, 31% with the nitroglycerin test and 73.9% with the metaproterenol test. Clearly, the effort and metaproterenol tests are pathological in the majority of cases, both tests inducing physiologically vasodilation and increase in the peripheral pulse. The arm-down test, which usually induces vasoconstriction, is almost always normal. Since the percentage of pathological responses to the nitroglycerin test is significantly smaller than that to the effort and metaproterenol tests, it is concluded that the vascular changes induced by aging are primarily functional, at least in asymptomatic subjects. Aging more negatively influences the vasodilating than the vasoconstricting ability.

An improved technique for obtaining cortical photoelectric plethysmograms.

An improved technique for obtaining cortical photoelectric plethysmograms.