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Biomedical subjects

O Tochikubo

Publications and source records attributed to O Tochikubo.

At least 109 records · Page 6Linked to original sources
PubMed1986

Non-Gaussian distribution of arterial pressure and heart rate during sleep and waking in hypertensive and normotensive subjects.

For statistical analysis of 24-hour recordings of arterial pressure (AP) and heart rate (HR), it is necessary to establish a theoretical probability density function of the distributions. In the present study, 24-hour recordings of direct AP and HR were performed in 15 normotensives (NT) and 39 patients with essential hypertension (EH) by means of a new portable device with a digital memory for analyzing frequency histograms. In both NT and EH, frequency histograms of AP (systolic and diastolic AP) and HR during a 24-hour period showed bi-modal curves, whereas those made during sleep and waking produced asymmetrical patterns resembling Gamma distribution. From the AP and HR histograms made for each subject during sleep and waking, such parameters as mean (M), standard deviation, mode (Mo), skewness (Sk), kurtosis (K) and minimum values (Mi) were calculated. The Sk and M minus Mo were positive, and K was greater than 3 in both HR and AP histograms; the AP and HR histograms during sleep can be more correctly analyzed with Gamma distribution (mean parameter errors were less than 7.3%) than with Gaussian distribution (in this: S = O, M minus Mo = O, K = 3). The Mi would accord with the location parameter of the Gamma distribution.

Adult↗
PubMed1986

A new portable device for 24-hour recording of ambulatory intra-arterial blood pressure and heart rate in hypertensive patients.

A new portable device (measuring 14 X 11 X 5 cm, weighing 600 g) has been developed for recording ambulatory intra-arterial blood pressure (BP) and R-R intervals on the electrocardiogram at 10 sec intervals throughout a 24 hour period and a computer system for analysis of the 8,640 digital recordings of systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR). Using this device, SBP, DBP and HR recordings were obtained in 12 normotensive patients and 37 patients with essential hypertension (of whom 19 presented in WHO Stage I and 18 in WHO Stage II). The 24-hour BP variation (SD) increased with increasing 24 hour mean BP but there was no difference of statistical significance in SD/mean among the 3 groups. There was a good correlation (r = 0.70 to 0.94) between SBP and DBP during 24 hours. The average of A in the linear regression equation, SBP = A X DBP +B, was greatest for patients with WHO Stage I and the average of 24-hour HR was highest for this group. The results suggested that these patients were in a hyperdynamic cardiac state. The new portable SBP-DBP-HR recorder is easy and simple to use and has the advantage of being low-cost, and therefore will be useful in clinical applications.

Ambulatory Care↗
PubMed1986

Noninvasive measurement of baroreflex sensitivity index using an indirect and continuous blood-pressure recorder.

The index of the baroreceptor reflex sensitivity (BRS) was measured noninvasively by monitoring the arterial pressure (AP) of the finger and R-R interval on the ECG during a Valsalva maneuver. An indirect finger AP measurement system was newly designed on the basis of the so-called vascular unloading technique. The BRS index was determined as the slope of the linear regression equation between the R-R interval and the virtual brachial AP which was evaluated from the finger AP. The data on both parameters were taken from the second period of the fourth phase in the Valsalva maneuver. The measurement was carried out on 24 inpatients (29-65 years) with essential hypertension. The conventional invasive method using phenylephrine or nitroglycerine was also performed on the same subjects. The correlation coefficient between the invasive and noninvasive methods was 0.81 when phenylephrine was used and 0.90 with nitroglycerine (p less than 0.001). The present method was found useful in routine clinical examination because of its easy and repeatable noninvasive application to patients without causing stress.

Adult↗
PubMed1985

A new portable device for recording 24-h indirect blood pressure in hypertensive outpatients.

To simplify 24-h blood pressure (BP) recording in hypertensive outpatients, we devised a new portable, automatic BP recorder and studied its accuracy and usefulness. The fully automatic recorder, measuring 5 x 16 x 18 cm with a cuff of usual size, weighs approximately 1 kg and is driven by a rechargeable battery. The cuff is inflated by a compact CO2 cartridge and two microphones are used to detect differentially the Korotkoff sounds in the upper arm. Systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) are automatically measured, displayed with the time of measurement, and recorded on a memory card at intervals of 15 min for 24 h. This equipment has high noise immunity and works very quietly. It predicts approximate BP during the period of increasing cuff pressure, and measures BP more quickly than the conventional method (the time required for each measurement was reduced by about half). Afterwards, mean values with standard deviations, trendgrams and histograms of BP and HR over a certain period of time can be displayed and recorded with an accessory analyser. The accuracy of the BP values recorded by this device were compared with those measured by the auscultatory method. The average differences were -0.6 +/- 2.1 (s.d.) mmHg for SBP and 0.2 +/- 3.0 mmHg for DBP (n = 152). The BP values by this method were also compared with those obtained directly from the brachial artery, the differences being -5.8 +/- 5.9/0.3 +/- 6.0 mmHg (n = 85). In 30 ambulatory hypertensive patients, 24-h BP was recorded using this recorder.(ABSTRACT TRUNCATED AT 250 WORDS)

Auscultation↗
PubMed1984

Renal haemodynamics and the renin-angiotensin system in adolescents genetically predisposed to essential hypertension.

Relationships between renal haemodynamics and the renin-angiotensin system were examined in 128 male adolescents with differing predispositions to hypertension. Baseline renal vascular resistance (RVR) was significantly elevated in the normotensive subjects with a positive family history, NT (FH+) group, than in the normotensives with a negative family history, NT (FH-) group, while there were no significant differences in other characteristics between the two groups. The borderline hypertensive subjects with a positive family history, BH (FH+) group, showed an even bigger increase in RVR and also had elevated plasma renin activity (PRA). In the NT (FH+) and BH (FH+) groups RVR correlated significantly with PRA levels. When captopril was given, the increased RVR in the NT (FH+) and BH (FH+) groups decreased, in correlation with baseline PRA, to levels not significantly different from those in the NT (FH-) group, in which no significant changes occurred in RVR. These results suggest that RVR may increase primarily in adolescents genetically predisposed to essential hypertension and that the renin-angiotensin system may play an important role in the mechanism of this increase in RVR.

Adolescent↗
PubMed1983

Environmental and physiological characteristics in adolescents genetically predisposed to hypertension.

To clarify the possible risk factors for the development of hypertension, we examined the influences of heredity and environment on blood pressure regulation and whether or not the physiological condition differed in high school students with different levels of blood pressure. A borderline hypertensive (BH) group, consisting of 75 male students with systolic blood pressure (SBP) consistently above 140 mmHg on two separate occasions, was compared to a normotensive (N) group of 84 male students with SBP below 130 mmHg. In the BH group, 43% of students had a family history of hypertension within two generations of relatives, while 18% had one in the N group (p less than 0.05). The BH group was characterized by a gain in weight, a slight increase in 24-hour urinary sodium excretion, a higher heart rate, elevated values of plasma renin and urinary aldosterone, and an elevated sodium concentration in erythrocytes. Nevertheless, urinary excretion of potassium and kallikrein did not differ between the two groups. In each group, students with familial hypertension had a significantly (p less than 0.05) lower 24-hour urinary kallikrein excretion than those without it. Although kallikrein excretion correlated fairly well with aldosterone excretion (r = 0.47, p less than 0.01) or creatinine clearance (r = 0.59, p less than 0.01) in the BH students without familial hypertension, no such correlations were found in those with familial hypertension. These results indicate that the abnormal relationships of aldosterone to kallikrein metabolism and of kallikrein to renal function control may be involved as hereditary factors in the development of hypertension.

Adolescent↗
PubMed1982

Cation imbalance in erythrocytes, serum and 24-hour urine from patients with essential hypertension and adolescents with high blood pressure.

Electrolyte concentrations in the erythrocytes, serum and 24-hr urine were measured in 34 untreated essential hypertensives (EH), 32 normotensives with a family history of hypertension (N+), 112 normotensives without a family history of hypertension (N-), 76 senior high school students with high blood pressure (H) and 110 students with normal blood pressure (C). For the measurement of intra-erythrocyte electrolytes, a new method to decrease the trapped plasma was developed and adopted. A new simple method to collect 24-hr urine was devised, too. The results were as follows: 1) The sodium concentration [Na] and the ratio of [Na] to potassium concentration [Na/K] in the erythrocytes were significantly higher in the EH and N+ than in the group of N- (p less than 0.01). 2) There was a positive correlation (r = 0.43) between the [Na/K] in the serum and erythrocytes in the 3 groups. The [Na/K] value in the erythrocytes to a given [Na/K] value in the serum was higher in EH than in the group of N-. 3) When the group of H was compared with C, the Na excretion of the 24-hr urine in the former group was found to be slightly higher, and the [Na/K] of the 24-hr urine and the [Na] and [Na/K] values of the erythrocytes were significantly higher, too. It may therefore be said that an increase in the intracellular [Na] or [Na/K], which may be caused genetically, and an excess of Na intake and an increase of the ratio of Na/K intake are presumed to play an important role in the pathogenesis of essential hypertension.

Adolescent↗
PubMed1981

Variability of arterial blood pressure and classification of essential hypertension by multivariate statistical analysis.

The subjects included in the present study were 141 hospitalized patients with essential hypertension (EH) and 45 patients with EH complicated with apoplexy and myocardial infarction. Of the former 15 underwent a 24-hour measurement of direct arterial pressure under unrestricted conditions, and 45 were examined for functioning of the carotid sinus reflex. (1) Even among the hospitalized patients with EH, blood pressure (BP) showed large diurnal variations. Falls and spontaneous fluctuations in BP were observed at a time during nocturnal sleep. The lowest BP (the "dale" pressure) observed at that time remained almost unchanged throughout the night (S.D. less than or equal to 6 mmHg) for each patient. Since casual BP varies considerably during a day, other laboratory findings should also be taken into account for evaluation prior to initiating antihypertensive treatment. (2) The 186 patients with EH were classified by multivariate statistical analyses of laboratory findings into 4 clusters (types). Then, a new severity index was made in order to evaluate atherosclerotic and hypertensive changes in each patient. (3) A newly devised carotid sinus stimulator was used to enhance the distensibility of the carotid sinus. A decrease in systolic blood pressure (delta SBP) was observed after stimulation although differences in delta SBP were found between the 4 clusters. There was a positive correlation between delta SBP and the elastic modulus of the common carotid artery (r = 0.55, P less than 0.01). (4) Each cluster was characterized by differences in plasma renin activity and cardiovascular abnormalities. This classification is considered to be useful for the antihypertensive treatment.

Adult↗