Amplitude Of Plethysmogram Research Articles

Effects of green tea and roasted green tea on human responses

Our objective was to elucidate the effects of tea consumption on refreshment and stress reduction/recovery through examining the multiple associations among factors such as various physiological responses and task performance. Participants included 20 healthy young men who performed a mental arithmetic task while 11 physiological responses were measured. The experiments were conducted twice under different beverage consumption conditions on separate days. The mental arithmetic task was executed six times in 1 day; participants ingested hot water, green tea, or roasted green tea (hojicha) before each task. Several subjective assessments: subjective fatigue, stress, mental workload, and flow were evaluated after each task. The R–R intervals, heart rate variability spectral components, the Poincaré plot indices (SD1 and SD2) and plethysmogram amplitude tended to decrease during task periods compared to resting periods. Tissue blood volume/flow (TBV, TBF) and near-infrared spectroscopy responses (NIRS) were lower in the tea condition than in the hot water condition. By scrutinizing various indicators, we found that aromatic stimulation of Japanese tea beverages has the potential to induce positive effects, enhance mental task performance, promote refreshment, and alleviate feelings of fatigue. These positive effects were observed even in small quantities and within a short duration, mirroring responses observed in daily consumption.

Immediate Effect of Specific Nostril Manipulating Yoga Breathing Practices on Autonomic and Respiratory Variables

The effect of right, left, and alternate nostril yoga breathing (i.e., RNYB, LNYB, and ANYB, respectively) were compared with breath awareness (BAW) and normal breathing (CTL). Autonomic and respiratory variables were studied in 21 male volunteers with ages between 18 and 45 years and experience in the yoga breathing practices between 3 and 48 months. Subjects were assessed in five experimental sessions on five separate days. The sessions were in fixed possible sequences and subjects were assigned to a sequence randomly. Each session was for 40 min; 30 min for the breathing practice, preceded and followed by 5 min of quiet sitting. Assessments included heart rate variability, skin conductance, finger plethysmogram amplitude, breath rate, and blood pressure. Following RNYB there was a significant increase in systolic, diastolic and mean pressure. In contrast, the systolic and diastolic pressure decreased after ANYB and the systolic and mean pressure were lower after LNYB. Hence, unilateral nostril yoga breathing practices appear to influence the blood pressure in different ways. These effects suggest possible therapeutic applications.

Early experience with remote pressure sensor respiratory plethysmography monitoring sedation in the MR scanner

The importance of monitoring the breathing pattern during sedation of children undergoing magnetic resonance scans is indicated in guidelines, but no appropriate magnetic resonance-compatible devices are available. We report preliminary findings from a technique referred to as remote pressure sensor respiratory plethysmography. A data acquisition system was developed, enabling measurement of respiratory rate, plethysmogram amplitude, proportion of inspiratory time over cycle time, thoraco-abdominal phase shift and sigh rate. Correlation between plethysmogram amplitude and tidal volume was investigated on adult volunteers. Twenty-seven children undergoing sedation were monitored with remote pressure sensor respiratory plethysmography, in addition to SPO2 and PetCO2. Differences in monitoring parameters were searched for among three groups: patients who received chloral hydrate only (chloral succeeded, CS group), those who received a supplementation of sodium thiopental (chloral failed, CF group), and those who were sedated with sodium thiopental directly (no chloral, NC group). Correlations were searched for among monitoring parameters, and with total dose of thiopental. The long-term behaviour of respiratory rate, proportion of inspiratory time over cycle time and phase shift was studied. Plethysmogram amplitude was found to correlate linearly with tidal volume (r>0.92), with a slope varying up to 22%. While 11% of patients did not tolerate the capnometric probe and readings were discontinuous in 26%, all of them tolerated remote pressure sensor respiratory plethysmography belts. Sighs and non-respiratory movements of the torso could be distinguished on remote pressure sensor respiratory plethysmography waveforms. No significant inter-group differences were found in PetCO2, SPO2, respiratory rate and phase shift. Proportion of inspiratory time over cycle time was higher in the NC group when compared to the CS group (0.497+/-0.03 vs. 0.463+/-0.008; P=0.02), the CF group being characterized by intermediate values (0.480+/-0.008); when compared to the CS group, sigh rate was lower in the CF group (0.04+/-0.04 vs. 0.14+/-0.08; P=0.04) and in the NC group (0.06+/-0.05 vs. 0.14+/-0.08, P=0.03). A positive correlation was found between total dose of thiopental and proportion of inspiratory time over cycle time, with r=0.4 and P=0.04. A large baseline variability in phase shift was found. No long-term trends predictive of patient movement could be identified. Breathing pattern monitoring is feasible through pneumatic devices, which are well tolerated. The resulting correlation with changes in tidal volume can be better when compared to visual inspection. Proportion of inspiratory time over cycle time and sigh rate convey information related to the state of the sedated patient. These results are not specific to the technology employed, and large-scale studies on the clinical usefulness of breathing pattern monitoring are motivated.

Multivariate workload evaluation combining physiological and subjective measures

This paper suggests a way to integrate different parameters into one index and results obtained by a newly developed index. The multivariate workload evaluation index, which integrates physiological parameters and one subjective parameter through Principle Components Analysis, was proposed to characterize task specific responses and individual differences in response patterns to mental tasks. Three different types of mental tasks were performed by 12 male participants. Heart rate variability, finger plethysmogram amplitude, and perspiration were used as physiological parameters. Three subscales, mental demand, temporal demand and effort out of six subscales in the NASA-Task Load Index were used as subjective scores. These parameters were standardized within each participant and then combined. It was possible to assess workload using this method from two different aspects, i.e. physiological and subjective, simultaneously.

Automatic changes in Brahmakumaris Raja yoga meditation

This report presents the changes in various autonomic and respiratory variables during the practice of Brahmakumaris Raja yoga meditation. This practice requires considerable commitment and involves concentrated thinking. 18 males in the age range of 20 to 52 years (mean 34.1 ± 8.1), with 5–25 years experience in mediation (mean 10.1 ± 6.2), participated in the study. Each subject was assessed in three test sessions which included a period of meditation, and also in three control (non-meditation) sessions, which included a period of random thinking. Group analysis showed that the heart rate during the meditation period was increased compared to the preceding baseline period, as well as compared to the value during the non-meditation period of control sessions. In contrast to the change in the heart rate, there was no significant change during meditation, for the group as a whole, in palmar GSR, finger plethysmogram amplitude, and respiratory rate. On an individual basis, changes which met the following criteria were noted: (1), changes which were greater during meditation (compared to its preceding baseline) than changes during post meditation or non-meditation periods (also compared to their preceding baseline); (2) , Changes which occurred consistently during the three repeat sessions of a subject and (3), changes which exceeded arbitrarily-chosen cut-off points (described at length below). This individual level analysis revealed that changes in automatic variables suggestive of both activation and relaxation occurred simulataneously in different subdivisions of the automatic nervous system in a subject. Apart from this, there were differences in patterns of change among the subjects who practised the same meditation. Hence, a single model of sympathetic activation or overall relaxation may be inadequate to describe the physiological effects of a meditation technique.

Pain and vascular reflexes in man elicited by prolonged noxious mechano-stimulation

Interdigital webs of the hands of human volunteers were pinched for periods of 2 min duration to induce tonic pain perceptions. During stimulation, the subjects gave estimates of their pain level at 10-sec intervals on a visual analogue scale, and the stimulus induced changes of the skin blood flow in the stimulated hand was assessed by photo-plethysmography. Sustained pinching induced a tonic reflex vasoconstriction in the stimulated hand with rather slow adaptation rate and no signs of habituation between trials. Step increases of the pinching force in the course of a stimulus were reflected by a decrease in plethysmogram amplitude as well as by increased pain ratings, although the subjects were usually unaware of these steps. Lowering the stimulus strength induced opposite, albeit much smaller effects in both pain ratings and vascular reactions. It is concluded that the vasomotor responses described in this paper are mediated by nociceptor input and reflect the processing of this input mainly at a spinal level.

Skin sympathetic activity in the tibial nerve triggered by vibration applied to the hand

The effect of vibration applied to the hand on skin sympathetic activity (SSA) in the lower limbs was studied in five healthy subjects. SSA from the right tibial nerve at the popliteal fossa, plethysmogram from the right index toe and perspiration from the sole of the right foot were measured when vibration of 100 m/s2 at 60 Hz was applied to the left palm for 1 min. The SSA response to vibration exposure differed among subjects, but every subject showed an increase in SSA from the tibial nerve when vibration was applied to the hand. Decrease in amplitude of plethysmogram from the toe was also found in all subjects. One subject displayed a remarkable increase in perspiration on the sole of the foot together with a great increase in SSA. The present findings indicated that even vibration exposure of the hand triggers sympathetic activity in the tibial nerve innervating the foot, and causes vasoconstriction of the toe and perspiration on the sole of the foot.

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.

CHANGES IN PLETHYSMOGRAPH ON CALORIC IRRIGATION

This study was performed in order to examine whether a condition of subjective-objective autonomic nervous functions could been conjectured or not, from the rate of diminution of amplit-ude of plethysmogram while caloric irrigation. The subjects were 30 patients selected from from patients complaining of vertigo or equilibr-lum disturbance. These patients wer devided into 3 groups, that is, first group was patients of Meniere's disease or Meniere syndrom, second group was patients of Orthostatic-dysreguation or vegetative dysregulation and third group was patients with loss of vestibular reaction involving acusticus neurinoma.A reflection photoelectric plethysmograph was attached on tip of second finger and vestibular stimulation the irrigation of water of 30°C and 40° into the external auditory canal for 40 seconds.The changes of amplitude of plethysmogram, the duration time of nystagmus and subjective-objective autonomic nervous symptomns were measured. Central and peripheral autonomic ervous function test were examined before or after the stimulation.This data was dealt with analysis of multiple egression and the correlation and the weight of factors were computed, Results1. Caloric stimulation resulted in the increase in 53%, the decrease in 19% and no change in 28% of pulse rate.2. A correlation was recognized between the rate of diminution of amplitude on maximum reaction point and the appearance of caloric nystagmus.3. Points of autonomic nervous symptoms registered the lowest point in the third group, next in the first group and the highest point in the second group.4. From the correlation coefficient, it is concluded that, there was correlation between the rate of diminution of amplitude and the duration time of nystagmus, autonomic nervous symptoms, Mecholyl test.5. Analysis of multiple regression resulted in the following regression equation.Y=43.173 +0.079503×1-0.82767×2+2.01735×3+4.2567×4- 2.0375X5- 1.3427X6.From that standard regreesion coefficient, it is considered that the rate of diminution of wave in caloric irrigation was mainly influenced by vestibular reaction and autonomic nervous system, especially central autonomic nerve.6. Multiple correlation coefficient of all subjects was 0.6975. The coefficient of second group was the highest value of 0.8301, the coefficient DP group was higher than the one cf CP group in first group.

CHANGES IN FINGER PLETHYSMOGRAPH DUE TO CALORIC VESTIBULAR

On 40 normal subjects aged 10-19, 20-29, 30-49, and over 50 years, 10 subjects in each age group, caloric irrigation in external auditory canal was conducted. Water temperature was 30°C and 4°C. During the test, reflection photoelectric plethysmograph was attached on the tip of each index finger of both hands and the changes of amplitude of plethysmogram were measured. On 8 subjects, the test was repeated 4 times under the same condition, and the reappearance of this reaction was examined. Results were as follows in : 1. There was a significant difference between the reaction in those under 50 years of age and those over in the rate of diminution of waves on the maximum reaction point. 2. The rate of diminution of waves on the maximum reaction point was considerably consistent in the same subjects, although there were individual differences. 3. The author presumed that the reaction of diminution of waves in this test was mainly due to vestibular stimulation induced by caloric irrigation, although there might be other non-vestibular reactions.