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Stiffening of the small artery may be the earliest sign of arteriosclerosis. However, there is no adequate method for directly assessing small arterial stiffness. In this study, the finger arterial elasticity index (FEI) was defined as the parameter n which denotes the curvilinearity of an exponential model of pressure (P)-volume (V(a)) relationship (V(a) = a - b exp (-nP)). For the original estimation, the FEI was calculated from a compliance index from the finger photoplethysmogram whilst occluding the finger. A simple estimation of the FEI was devised by utilizing normalized pulse volume instead of the compliance index. Both estimations yielded close agreement with the exponential model in healthy young participants (study 1: n = 19). Since the FEI was dependent on finger mean blood pressure, normalized finger arterial stiffness index (FSI) was defined as standardized residual from their relationship: mean and standard deviation (SD) of the FSI were 50 ± 10 (study 2: n = 174). The mean coefficient of variation of the FSI for four measurements was 5.72% (study 3: n = 6). The mean and SD of the FSI in seven arteriosclerotic patients were 100.0 ± 13.5. In conclusion, the FEI and FSI by simple estimation are valid and useful for arteriosclerosis research.

A novel index of finger arterial stiffness (FSI) was tested in terms of the relationship with risk markers for preclinical cardiovascular disease. In addition, we examined if the association between psychosocial factors and FSI was explained by allostatic load markers in 37 healthy young men aged 24.8 ± 4.0 years. The FSI was devised based on an exponential model of the finger arterial pressure-volume relationship. The allostatic load index (ALI) as a cumulative risk marker was defined by the mean of standard scores for nine variables: resting systolic and diastolic blood pressure, waist/hip ratio, high-density lipoprotein cholesterol (HDL-C), total cholesterol/HDL-C ratio, triglycerides, hemoglobin A1c, insulin resistance, and high sensitivity C-reactive protein (CRP). Partial correlations controlling for age were significant for FSI with HDL-C (r = −.36), CRP (r = .39), ALI (r = .40), unhealthy overall eating habits (r = .34), hostility using the Buss-Perry Aggression Questionnaire (r = .38), and manageability in Sense of Coherence (r = −.38). In conclusion, FSI seems to be associated with vascular proinflammation as well as with overall physiological dysregulation and allostatic load. These associations were moderated by eating lifestyle and psychosocial stress.

Assessment of recovery is important for the investigation of stress but has been compounded by difficulties, in particular contamination by the carryover effect. In the present study, the mean recovery rate (MRR) was used in order to overcome this difficulty. First, the validity of the MRR was demonstrated theoretically. Second, it was demonstrated experimentally, when a comparison was made with the validity of the mean recovery per se. In the experiment, data on beat-by-beat systolic blood pressure, obtained from 18 participants before, during, and after mental arithmetic, were used as a typical sample. The implications of these results for the understanding of recovery measures are discussed.

Eighteen young females performed two kinds of mental tasks, an Internally-Generated Mental Arithmetic task (IGMA: serial subtraction) and an Externally-Presented Mental Arithmetic task (EPMA: continual subtraction). Both tasks were equal in establishing active coping, but EPMA made participants attend more to an external stimulus. The expected reaction patterns were vascular-dominant (blood pressure elevation mainly due to an increase in total peripheral resistance) for only EPMA, or cardiac-dominant (mainly due to an increase in cardiac output) for both IGMA and EPMA. The results showed that vascular-dominant patterns were evoked during EPMA, while mixed (moderate increases in both cardiac output and total peripheral resistance) reaction patterns were evoked during IGMA. Post-task questionnaires confirmed that attention to an external stimulus was required much more in EPMA than in IGMA. These results indicate that the vascular-dominant reaction pattern was evoked in the state where attention to an external stimulus was heightened. The implications of the present findings are discussed in term of how to interpret the hemodynamic reaction patterns during mental stress.

A quantitative scale for identifying cardiac versus vascular reactor, balance of blood pressure equivalents (BE), was newly advocated and compared with a very recently advocated one, hemodynamic profile (HP), by Gregg, Matyas and James (2002). BE was defined as “(ΔQ/Q0)P0′ − (ΔR/R0)P0.” Here, P0, Q0, and R0 were mean blood pressure (P), cardiac output (Q), and total peripheral resistance (R) during baseline, and ΔQ and ΔR were the difference scores of Q and R from baseline to stress, respectively. This was named as BE because the two terms in the formula indicated changes in Q and R in their blood pressure equivalents. Comparisons of the BE and HP scales were carried out, theoretically, in a newly introduced pressor space, on orthogonality with the extent of elevation of P (ΔP); and then, practically, by using hypothetical data. In summary, it was shown that data points in the neighborhood in the pressor space can be judged as having not so different hemodynamic balance whether the BE or HP scale was used. As a merit, the BE scale seemed helpful to an intuitive understanding of the hemodynamics during stress. As a demerit, it cannot maintain the quasi-orthogonal relationship with ΔP when Q or R changes profoundly in the face of stress.

Jets issuing through small holes into a freestream have proven effective in the control of boundary layer separation. The beneficial effect of separation control is obtained only if the jets are pitched to the lower wall and skewed with respect to the freestream direction. In the previous study, the suppression effect of the orifice shape on flow separation was reported for three types of jet orifice (circular, triangular and square orifices). The triangular orifice generates the strong vortex and makes effective the pressure recovery in the diffuser in comparison with the circular and square orifices. In this study, four types of the jet orifice (model-U, model-D, model-R and model-L) are installed and the effect of the direction of the vertex of the triangular orifice on separation control is investigated in a two dimensional diffuser. Separation control is accomplished by all models, however the suppression of flow separation is most ineffective among the four models in the case of model-L (the vertex points to the direction of the jet pitch angle).

The pulsatile ac component (Δ I ) superimposed on the transmitted dc components ( I : tissue plus blood) are obtained from a near-infrared finger photoplethysmogram using a wavelength of 810 nm. Only the dc component is given in an ischaemic circulatory state ( I t : tissue only). Based on Lambert–Beer's law, normalized pulse volume (NPV; =Δ I / I ) and blood volume [BV; = ln( I t / I )] have recently been advocated as quantitative measures. In this study, the NPV–BV relationship was examined using the finger occlusion method during rest and mental arithmetic in 16 female undergraduates. Finger vascular tone during stress was evaluated by the distance of the linear and parallel NPV–BV regression lines ( D NB ) between rest and stress conditions. A reference standard was provided by the linear regression lines of compliance index (CI=NPV/pulse pressure) and BV to the transmural pressure. The estimates at 40 mmHg of transmural pressure, as an arbitrarily chosen reference point, were calculated (CI40 and BV40). D NB correlated well with them ( r =0.81 and 0.94, respectively). The multiple regression with mean blood pressure indicated that the combination of D NB and the reactivities in heart period could explain approximately 50% of valiance in pressor response. In conclusion, D NB is easily obtainable from the NPV–BV function and seems to be more specific and valid than NPV as an index of finger sympathetic tone, since it adjusts the mechanical effect of arterial distending pressure.

Yaezawa and Yoshida's (1981) findings on the effects of an intrusion on personal space were reinvestigated. Thirty-five female students were confronted with the approach of a male stranger, and blood pressure (BP) and heart rate (HR) were monitored. Throughout the model's approach, HR showed a significant triphasic change (an initial decrease, a subsequent increase, and then a secondary decrease), whereas subjective feelings of anxiety and tension showed significant, gradual increases. These trends were similar to those of Yaezawa and Yoshida’s. Nonetheless, their explanation that the triphasic change in HR reflected once hightened and then relieved tension, which was incongruent with the subjective ratings, seemed questionable. As the BP elevated to a moderate degree in spite of the modest HR changes, total peripheral resistance must have been increasing during the model's approach. Blood pressure elevations via this sort of hemodynamic pressor mechanisms have often been reported when a person can only tolerate passively during exposure to stress. This seems to be the case in an intrusion on personal space.

This study examined the newly proposed indices for estimating finger vascular tone, which can be obtained from near infrared transmittance photoplethysmographic recordings; normalized pulse volume (NPV) and blood volume (BV). They were recorded for seven male and two female students under continuous infusion of and recovery from propofol. Concomitant hemodynamic measurements were made with a non-invasive impedance cardiograph and a continuous blood pressure monitor. Normalized pulse volume showed no apparent dose-dependency and was negatively correlated with total peripheral resistance. In contrast, BV increased dose-dependently with propofol concentration and was negatively correlated with cardiac preload index (PLI) and with stroke volume (SV) at higher concentrations. The supplementary structural equation modeling procedure effectively illustrated causal relationships between BV, PLI and SV. In conclusion, the present data suggest that NPV and BV independently reflect arterial and venous tone in the finger tip, respectively. Although the underlying mechanisms remain unclear, BV is more sensitive to vascular dilation under propofol anesthesia.

Normalized pulse volume (NPV, Sawada, Tanaka, & Yamakoshi, 2001) was calculated on a beat-to-beat basis by dividing the ac component by the dc component in near-infrared finger photoplethysmogram. Finger arterial compliance index (CI) was obtained by dividing NPV by the respective pulse pressure. Twelve female subjects underwent immersions of the contralateral hand in water at two different temperatures (44 degrees C, 22 degrees C). During the last 3 min of each of the 8-min resting and immersion conditions, CI was measured for the finger position at heart level, 15 cm, and 30 cm below the heart for 1 min each. Results indicated that a negatively linear regression could be applied to the beat-to-beat data on log CI and mean blood pressure (MBP) over the three finger position (whole regression). CI calculated at 90 mmHg (CI 90) was arbitraily chosen as a reference point for comparing compliance among conditions. CI 90 decreased significantly during the 22 degrees C condition. In conclusion, CI seemed more valid as an index of the finger arterial vascular tone through the removal of MBP influence.

Abstract After a hint from Lang et al.'s (1997) defence cascade, researchers considered cognitive process experienced when encountering mental stress to be composed of four elements: (serially) first attention (Attent), second unpleasant affect (UnplAff) and sometimes pleasant affect (PlAff), and third cognitive coping (CogCop). The present study investigates the effect of each cognitive element on the provocation of the well-known vascular-dominant reaction pattern during mirror tracing: elevation of mean blood pressure mainly because of increases in total peripheral resistance. Twenty-four male students first underwent four computer-simulated mirror-tracing practices of 3 min each, then a 7 min adaptation followed by a 3 min baseline, and further four kinds of actual mirror tracing trials (Attent, UnplAff, PlAff, and CogCop) of 3 min each. Results on the cardiovascular measures indicated that every mirror-tracing trial indisputably provoked the vascular-dominant reaction pattern. An alpha-adrenergic vascular sympathetic activation was heightened. Self-report measures on the four cognitive elements suggested that heightened Attent seemed to contribute to provoking the reaction pattern. Although the UnplAff and PlAff trials had an active coping feature in a narrow sense, they could not provoke the cardiac-dominant reaction pattern. Differences in task difficulty among the mirror tracings could not explain the results. The implications of these results are discussed in order to better understand cardiovascular hemodynamics during mental stress.

This study examined estimates of finger vascular tone, obtained from photoplethysmography. Normalized and double-normalized pulse volume (NPV and DNPV), blood volume (BV), and pulse volume (PV) were obtained in 2 male and 7 female middle-aged patients at an outpatient office 1–3 days before an operation and in the operating room before and after anesthesia by propofol. There was a preoperative decrease in NPV, and the propofol injection yielded a moderate increase in BV. The latter seemed to contribute to a decrease in DNPV. A partial correlation controlling for body mass index was observed between the change in NPV and the dose of propofol; a larger reduction in NPV before anesthesia compared with the control condition was accompanied by the need for a greater infusion of propofol for sedation. In conclusion, among the measures examined, NPV appears to be the best indicator of heightened arteriolar vascular tone.

Normalized pulse volume (NPV) was advocated as a more valid measure for the assessment of finger vascular tone. Based on the optical model in the finger tip expressed by Lambert–Beer's law, NPV is expressed as Δ I a / I . Here, Δ I a is the intensity of pulsatile component superimposed on the transmitted light ( I ). Theoretically, NPV seems to be superior to the conventional pulse volume (PV; corresponding to Δ I a ). Firstly, NPV is in direct proportion to Δ V a , which is the pulsatile component of the arterial blood volume, in a more exact manner. Relatedly, NPV can be processed as if it is an absolute value. Secondly, the sensitivity of NPV during stressful stimulations is expected to be higher. These expectations were supported experimentally using 13 male students. Firstly, the correlation between cutaneous vascular resistance in the finger tip (CVR) and NPV was higher than that between CVR and PV among all the subjects, although there was not much difference between these correlations within each subject. Secondly, NPV decreased much more than PV during mental stress. Some limitations of the present study were addressed, including the point that certain factors can violate the direct proportional relationship of NPV and PV to Δ V a .

In order to obtain basal information about what type of externally paced respiration is comfortable, 25 male and 25 female undergraduate students were asked to practice self-paced respiration. After a 1-min rehearsal following instructions on comfortable self-paced respiration, subjects carried out 2 min of self-paced respiration and rated their level of comfort on a scale of 1–5. This was repeated (up to a maximum of seven times) until the subject recorded a high rating. Results indicated that self-paced respiration was most comfortable, irrespective of sex, when a respiratory pattern was attained of half the respiratory rate and nearly twice the tidal volume of the trainee's resting condition. Although respiratory sinus arrhythmia and heart rate were indicative of a decrease in cardiac vagal activity and end-tidal PCO2 was suggestive of a reduction in anxiety, these effects were small. The results have implications for the utilization of externally paced respiration.

Near-infrared finger photoplethysmograms were recorded and double-normalized pulse volumes (DNPV = DeltaV(b)/V(b); V(b) = total blood volume in the fingertip, DeltaV(b) = pulsatile component of V(b)) were calculated in ten subjects during, immersion of the contralateral hand in water at three different temperatures (44 degrees C, 22 degrees C, 11 degrees C). The DNPV from the left finger was compared beat-by-beat with cutaneous vascular resistance (CVR) derived by dividing mean blood pressure of the left third finger by cutaneous blood flow of the left fourth finger. The correlations overall at the three temperatures between log DNPV(LF) and log CVR(LF) (LF, low frequency component of DNPV and CVR) ranged from -0.89 to -0.96 among the subjects. After adjusting for a maximal extension of the vascular wall (DNPV(max)), the correlations became stronger. It was concluded that DNPV was a reliable and valid indicator of vascular tone in the finger.

In this study, one of the predictions of the reactivity hypothesis was investigated: the intertask consistency of blood pressure (BP) responses. Twelve young male subjects underwent cold-pressor (14°C) and digit-scan (counting even numbers) tests in randomized order. Cardiovascular parameters were recorded during a 2-min pretask baseline, a 10-min stressful exposure, and over a 5-min post-task baseline. The intertask correlations between the cold pressor and digit scan increased with prolonged exposure and were higher for almost all of the systolic BP measurements than for the diastolic measurements. After prolonged exposure, the hemodynamic mechanisms of BP elevations during the digit scan shifted from an increase in both cardiac output and peripheral vascular resistance to solely an increase in peripheral vascular resistance. Increased peripheral vascular resistance was the consistent cause of the BP elevations with the cold pressor. Accordingly, the hemodynamic shift on the part of the digit scan seemed to heighten the intertask BP correlations. Some other factors influencing the intertask BP correlations are also discussed.

Sixteen young males underwent resting and mental arithmetic and were injected with 100 μg phenylephrine during the interventions. Half of them further underwent trinitroglycerine injections. Power spectral density for inter-beat interval variability was calculated using the maximum-entropy method (MEM) with a very high lag, and its validity was checked by nonlinear least-squares method. It was found that the MEM could produce a very accurate power spectral density. Results on the low- and high-frequency (LF and HF) powers indicated that the phenylephrine injection increased both the LF and HF powers, that the trinitroglycerine injection increased the LF power to some degree, and that the mental arithmetic decreased both the LF and HF powers with both phenylephrine and trinitroglycerine. Therefore, the LF power could be interpreted as a marker of both the vagal and sympathetic activities, whereas the HF power seemed to be solely associated with vagal activity. The implications of the interpretation are discussed in terms of the controversy on the LF power (vagal plus sympathetic vs. sympathetic).

Blood pressure is one of the most commonly recorded functions in physiology and medicine, and it has become a major variable in recent psychophysiological and behavioral medicine research. Many methods have been developed for the measurement of blood pressure in clinical, laboratory, and natural settings. The broad objectives of this report are to summarize the most critical methodological issues in the measurement of blood pressure and to present principles and recommendations for the evaluation of blood pressure methods and findings in published studies.

The primary purpose of this study was to examine the covariation between preload (PL) and other cardiovascular stress responses during mental arithmetic (MA) and reaction time (RT) tasks. PL, stroke volume (SV), cardiac output (CO) and pre-ejection period (PEP) were obtained using impedance cardiography. Mean blood pressure (MBP) was measured by the vascular unloading method. Thirty-one male college students were given both MA and RT tasks with a counterbalanced order. Results indicated significant differences in heart rate reactivity which seems to provide evidence for a stronger vagal withdrawal in MA. Changes in CO and MBP were identical in these two tasks which might have resulted from a compensatory change in PL and SV. Specificity of PEP for the increased beta-adrenergic activity was supported by the correlation pattern among PL, MBP and PEP. The results were discussed in the context of cardiovascular regulating mechanisms.

The purpose of the present study was to investigate the reproducibility of the increases in blood pressure found in our recent study on exposure to intermittent noise, to confirm the haemodynamic mechanism raising blood pressure (via an increase in peripheral vascular resistance expected to be specific to passive coping), and to assess baroreceptor cardiac reflex sensitivity in connection with the blood pressure elevation. A group of 16 young normotensive men participated in the experiment and underwent a 10-min intermittent exposure to pink noise at 100 dB (sound pressure level). The subjects also underwent three other stresses: a 1-min cold pressor test, a 3-min isometric handgrip and 3-min of mental arithmetic. The results indicated that blood pressure was elevated reproducibly for most of the noise exposure periods and that peripheral vascular resistance increased simultaneously, as expected. Baroreflex sensitivity was not suppressed. The results, as a whole, were in agreement with our recent findings for exposure to a similar type of noise and thus the reproducibility was corroborated. The mechanism raising blood pressure was similar in the cold pressor test. Conversely, during the isometric handgrip and mental arithmetic, blood pressure elevations were attributable mainly to increases in cardiac output. The implications of the opposing haemodynamic mechanisms raising blood pressure among the four stressful tasks have been discussed in relation to active versus passive coping required for each task. Differences in the magnitude of suppression observed in baroreflex sensitivity among the tasks have also been discussed in the context of defence reactions.

This study examines cardiovascular recovery from mental stress. Investigating the absence or presence of carryover effect, the effect of the final reactivity observed at the end of stressful task on the successive recovery, was the major objective. A recently advocated recovery measure related to the area under the curve, mean recovery rate (MRR), was investigated, comparing with the two relatives of this type, total carryover (TCO) and literally area under the curve (AUC). At the onset, a detailed theoretical formulation of each measure was carried out, starting from its original definition. It was predicted that MRR, but not TCO or AUC, could be free from the carryover effect. Next, 88 male students underwent a 5-min mental arithmetic during which blood pressure and heart rate were measured. Nearly all the theoretical predictions (i.e., 5/6 for the three recovery measures by two cardiovascular parameters) were supported by experimental data. There was only one exception: for heart rate, there was a proportional relationship even for MRR versus the final reactivity. Vagal rebound in the recovery period was conceived as the main contributor of this contradiction. The implications of these results for the understanding of future directions in recovery studies are discussed.

Prolonged monotonous driving may lower a driver's awareness level as well as increasing their stress level due to the compulsion to maintain safe driving, which may result in an increased risk of a traffic accident. There is therefore an opportunity for technological assessment of driver physiological status to be applied in-car, hopefully reducing the incidence of potentially dangerous situations. As part of our long-term aim to develop such a system, we describe here the investigation of differential skin temperature measurement as a possible marker of a driver's stress level. In this study, healthy male (n=18) & female (n=7) subjects were investigated under environment-controlled conditions, whilst being subjected to simulated monotonous travel at constant speed on a test-course. We acquired physiological variables, including facial skin temperature which consists of truncal and peripheral skin temperatures (T s ) using thermography, beat-by-beat blood pressure (BP), cardiac output (CO), total peripheral resistance (TPR), and normalized pulse volume (NPV) used as an indicator of local peripheral vascular tone. We then investigated the driver's reactivity in terms of skin temperatures with this background of cardiovascular haemodynamics. We found that the simulated monotonous driving produced a gradual drop in peripheral T s following the driving stress, which, through interpretation of the TPR and NPV recordings, could be explained by peripheral sympathetic activation. On the other hand, the truncal T s was not influenced by the stress. These findings lead us to suggest that truncal-peripheral differential T s could be used as a possible index indicative of the driver's stress.

Long hours of automobile driving under monotonous situations may cause the lowering of what we term a driver's activation state (DAS) or in other words the production of drowsiness, resulting in an increased risk of a traffic accident. There is therefore a need to create a newly advanced system focused on the DAS in-car, hopefully thus avoiding potentially dangerous situations. In order to develop such a system as a final goal, we have firstly set out to acquire such cardiovascular variables as beat-by-beat blood pressure (BP), RR interval from ECG and normalized pulse volume (NPV) used as a peripheral vascular tone of alpha-adrenergic sympathetic activity, during presentation to the driver of a screen movie simulating monotonous travel at constant speed on a test-course. Subsequently, we have investigated the reactivity in terms of the driver's cardiovascular hemodynamics. Through the successful monitoring of cardiovascular parameters during the movie presentation obtained in 11 healthy male subjects, the following results were obtained: The monotonous driving produces a statistically significant gradual rise in BP following drowsiness, which could be explained by enhancement of sympathetic activity using a time-frequency analysis of BP and RR. This finding strongly indicates that continuous driving in such monotonous situations can make a driver considerably stressful and thus may cause a gradual increase in BP, and that this gradual BP increase may be used as a possible index relevant to the DAS. This finding was also confirmed by the analysis of NPV, suggesting that the gradual increase in BP during the monotonous driving would be rather caused by a regulation of peripheral vasomotor constriction. Language: en

Prolonged periods of driving in monotonous situations may lower a driver's activation state as well as increasing their stress level due to the compulsion to maintain safe driving, which may result in an increased risk of a traffic accident. There is therefore an opportunity for technological assessment of driver physiological status to be applied in-car, hopefully reducing the incidence of potentially dangerous situations. As part of our long-term aim to develop such a system, we describe here the investigation of differential skin temperature measurement as a possible marker of a driver's stress level. 10 healthy male subjects were studied, under environment-controlled conditions, whilst being subjected to simulated monotonous travel at constant speed on a test-course. We acquired measurements of relevant physiological variables, including truncal and peripheral skin temperatures (Ts), beat-by-beat blood pressure (BP), cardiac output (CO), total peripheral resistance (TPR), and normalized pulse volume (NPV) used as an indicator of local peripheral vascular tone. We then investigated the driver's reactivity in terms of cardiovascular haemodynamics and skin temperatures. We found that the simulated monotonous driving produced a gradual drop in peripheral Ts following the driving stress, which, through interpretation of the TPR and NPV recordings, could be explained by peripheral sympathetic activation. On the other hand, the truncal Ts was not influenced by the stress. These findings lead us to suggest that truncal-peripheral differential Ts might be used as a possible index indicative of the driver's stress. Such an index, if decisively validated, would be easy to apply in real driving situations by using radiation thermometer.

Monotonous automobile driving for a long stretch of time and/or over a familiar route may cause the lowering of what we term a Driver’s Activation State (DAS), or in other words the awareness level, resulting in an increased risk of a traffic accident. There is therefore a need to create a newly advanced system focused on the DAS in-car, hopefully thus avoiding potentially dangerous situations. In order to develop such a system as a final goal, we have firstly set out to acquire such cardiovascular variables as beat-by-beat blood pressure (BP), RR interval from ECG and normalized pulse volume (NPV) used as a peripheral vascular tone of α-adrenergic sympathetic activity, during presentation to the driver of a screen image simulating monotonous travel at constant speed on a test-course. Subsequently, we have investigated the reactivity in terms of the driver’s cardiovascular hemodynamics. Through the successful monitoring of cardiovascular parameters during the image presentation obtained in 11 healthy male subjects, we have obtained the following interesting findings: That is, the monotonous driving produces a significantly gradual rise in BP, which could be clearly explained by enhancement of sympathetic activity using a time-frequency analysis of BP and RR. Additionally, it is suggested that this rise in BP during a monotonous situation may be caused by a regulation of peripheral vasomotor constriction rather than by cardiac-related control. This BP finding strongly indicates that the continuous driving in such monotonous situation makes a driver considerably stressful and thus may cause a gradual increase in BP, and that this gradual BP increase might be used as a feasible index relevant to the DAS.

Lowering of what we term a driver's Activation State (AS) during monotonous driving conditions may increase the risk of an accident. To develop an in-car environment that allows active driving - "Biofee dforward System" - we have investigated the effects of applying a stimulus of increased inspired oxygen fraction (FinfI/infOinf2/inf) supply on a driver's AS, using simulated monotonous driving. We used our previously substantiated index of As derived from beat-by-beat blood pressure (BP) response following an electrical stimulus. We have made physiological measurements including BP and found that the increased FinfI/infOinf2/infstimulus is effective in enhancing the AS. This finding was also confirmed in terms of the autonomic activity balance as well as the lengthening in time for active, safer, driving.

Given a hint from Lang, Bradley, and Cutbert's (1997) defense cascade, two cognitive processes, instead of passive versus active behavioral coping, which seem to have differential effects on the provocation of vascular- versus cardiac-dominant reaction pattern during mental stress were advocated: attention (Attent) versus unpleasant affect (UnplAff). Based on this notion the Attention-Affect Check List (AACL) was developed as a self-report measure. In addition, items on uncontrollability (Uncontr) were prepared for the purpose of checking whether heightened Attent and UnplAff are accompanied by alterations in Uncontr. Two hundred and eighty-four students underwent two kinds of mental stress, which seemed to specifically heighten Attent and UnplAff. Four factors with four items each were extracted from the AACL item pool: concentrated and allocated Attent, UnplAff, and pleasant affect. Also, one factor with four items was extracted from the Uncontr item pool. For both the mental stresses, each scale, although very brief, had quite reasonable alpha reliability. Accountability of each scale for the total variance was reasonably high. Some problems are discussed in relation to the validity of AACL.

A near-infrared finger photoplethysmogram adopting a wavelength of 810 nm provides data pertaining to the pulsatile a.c. component of finger blood flow (delta I) superimposed on the transmitted d.c. components in a normal ( I: tissue plus blood) and an ischaemic circulatory state ( I(t): tissue only). Simultaneous recording of finger blood pressure provides data pertaining to the distending pulse (PP) and mean blood pressure. Based on the Lambert-Beer law, indices of the arterial compliance (CI=delta I/ I/PP) and distensibility [DI=delta I/ I/ln( I(t)/ I)/PP] are advocated for assessing finger vasculature. The functional relationships between transmural pressure and CI and DI were examined using finger occlusion while performing an arithmetic test (i.e. a mental stress) in 16 females, and during reactive hyperaemia in 5. Gradual occlusion of the finger was conducted at 20-s intervals and the beat-by-beat transmural pressure was determined by calculating mean blood pressure minus the occluding cuff pressure. Logarithmically transformed CI and DI data were linearly associated with the transmural pressure; thus, the estimates obtained at a transmural pressure of 40 mmHg were chosen as an arbitrary reference point (CI40 and DI40). The results indicated that CI40 and DI40 were reduced while performing an arithmetic test, and increased during reactive hyperaemia. Responses were larger for CI40 than for DI40. In conclusion, noninvasive finger occlusion allowed the measurement of the compliance/distending pressure relationship, and CI40 could be utilised to evaluate changes in finger vascular tone.

In recent years, considerable attention has been focused on studies of stress reduction interventions. However, there have been controversies regarding their positive effects. The present paper is an attempt to initiate reconciliation of the discrepant findings. First, the term “stress” is redefined from a standpoint of cardiovascular hemodynamics. Then the attention-affect model is newly introduced in order to have a clearer understanding of the hemodynamic reaction patterns during stressful stimulation. Based on these reconsiderations, the stress reduction interventions are revaluated, with an emphasis on breathing training.