Biomedical subjects

Osamu Tochikubo

Publications and source records attributed to Osamu Tochikubo.

36 records · Page 2Linked to original sources

PubMed2004

Sodium intake and cardiac sympatho-vagal balance in young men with high blood pressure.

We have previously reported that a high sodium intake increases sleep-time blood pressure (BP) in young men. However, there are cases in which this relation does not apply. To account for them, we investigated the relation between sodium intake and cardiac sympatho-vagal balance (SVB) in young men with high BP. Sodium intake was estimated from the amount of urinary sodium excretion over 1 week. Twenty-four-hour (24-h) urinary sodium excretion (Salt24), 24-h ambulatory BP and ECG were obtained on the last day of the observation period. As an index of sodium intake, the expression In(Salt24/Cr24) (Cr24, 24-h urinary creatinine excretion) was used. From power-spectral analysis of ECG-RR intervals during sleep, we obtained the LF/HF ratio between the low-frequency component (LF) and the high frequency component (HF) and used it as an index of SVB. The subjects were male medical students divided into a normal BP group (N-group; n=103) and a high BP group (H-group; n=26, 24-h BP>125/75 mmHg). Mean In(Salt24/Cr24) and LF/HF in the H-group were significantly higher than those in the N-group (LF/HF: 1.86+/-0.44 [SD] vs. 1.37+/-0.30, p<0.001). The calculated discriminant function (D) for the H-group and N-group was D=1.6x + 5y - 11, where x is In(Salt24/Cr24) and y is LF/HF. This formula (D) resulted in high discriminant predictive accuracy (82%) between the groups. If D=0 (the value of the cut-off line determining separation of the groups), the relation y=-0.32x + 2.2 (negative relation between y and x) was obtained. These results suggest that excessive sodium intake in combination with accentuated SVB (LF/HF) increases BP in young men.

Adult↗

PubMed2004

Willingness to pay for a public health checkup program: assessment by the travel cost method.

OBJECTIVE: Whether the benefit of a public health program surpasses the cost of providing the program is an important question for public service providers. This study aimed to evaluate one health checkup program provided by a municipal government by measuring the public's willingness to pay (WTP) for maintaining the program. METHODS: A questionnaire-based study of a health checkup program targeting people joining the National Health Insurance system was conducted. The WTP was estimated from a demand curve for the program, which was constructed by a revealed preference method, that is, by the travel cost method. RESULTS: The WTP was calculated as 5410 yen per person, an amount substantially below the cost to the government of providing the service. The aggregate WTP was also estimated to be lower than the current expense of the municipal government. CONCLUSION: The amount users are willing to pay for a health checkup program provided by the municipal government appears to be less than the actual cost of the program. The travel cost method might reflect short-term private benefit produced by the health checkup program but cannot take into account long-term private benefit or overall social benefits which ensues.

Humans↗

PubMed2003

Relationship between visceral fat accumulation and hypertension in obese men.

PURPOSE: Visceral-fat (VF) accumulation is suggested to be a major contributor to such cardiovascular-disease risk factors as hypertension (H), glucose intolerance (G), and hyperlipidemia (L). We have devised a simple way of estimating VF accumulation, and investigated the relationship between VF and hypertension in obese men. METHODS: First, CT scan was used to measure VF area in the umbilical region in 108 obese men. Then the umbilical-region circumference (C) was measured with a tape measure and abdominal skinfold thickness (S) with a skinfold caliper. The data obtained with a model formula (VFe = alphaC2 - betaCS + gamma) and actual VF area were compared, and three coefficients, alpha, beta, and gamma, were calculated by means of multivariate analysis. Next, in 354 male company employees, VFe was estimated using this model formula, and cardiovascular risk factors were investigated. RESULTS: The formula for estimating VF (cm2) was VFe = 0.03C2 - 0.36CS - 47 (correlation coefficient; r = 0.72). Discriminant analysis between the merely obese group (O) and thegroup complicated by multiple cardiovascular risk factors (O, H, G, and L) determined a VFe-cutoff value of 120 cm2. Its discriminant sensitivity/specificity values were significantly higher than those based on body mass index (BMI) (cutoff value of 27 kg/m2) (p < 0.05). Hypertensive obese (HO) men with high VFe value (> 120 cm2) had a higher frequency of other risk factors (G or L: 86%). CONCLUSION: VFe is considered useful in estimating VF accumulation, and seems more effective than BMI for predicting multiple cardiovascular risk factors (VF syndrome) in obese hypertensive men.

Adipose Tissue↗

PubMed2003

Accuracy and applicability of the Terumo ES-H55 double-cuff sphygmomanometer for hospital use.

BACKGROUND: We have developed a new blood pressure (BP)-measuring device with a double-cuff, and evaluated its accuracy and applicability for practical use. DESIGN: The double-cuff method features a small cuff placed in the centre of the compression cuff to detect the oscillation of arterial pulsation, by which algorithms for the determination of systolic BP (SBP) and diastolic BP (DBP) were rendered more objective than with the conventional oscillometric method. Algorithms for automatic BP determination were developed from the oscillation data taken with the small cuff from 217 men and 256 women, and then installed in the Terumo ES-H55 device (length: 17 cm, weight: 120 g). This ES-H55 device was tested on 87 subjects (65 hypertensives and 22 normotensives) to compare its accuracy with that of the auscultatory method according to the AAMI SP-10 protocol. RESULTS: Using Bland and Altman scatter plots, the difference in SBP between the ES-H55 device and the auscultatory method was within +/- 5 mmHg in 88% of subjects, and within +/- 10 mmHg in 97% (mean difference +/- SD: 0.2 +/- 3.9 mmHg). The difference in DBP was within +/- 5 mmHg in 80%, and within +/- 10 mmHg in 97% (difference: -0.1 +/- 4.6 mmHg). These results satisfied AAMI guidelines, and this device was easy to use. CONCLUSIONS: The ES-H55 device is compact and light, with clear algorithms for the determination of BP, and satisfies AAMI criteria, so that it is considered a useful BP-measuring device that could be used instead of a mercury sphygmomanometer by nurses and doctors in hospital wards.

Adolescent↗

PubMed2003

Relation between sodium intake and blood pressure during sleep in young men.

In the past, cross-sectional studies of small groups have not always shown a significant relation between habitual sodium intake and blood pressure (BP). This study examined the relation between 24-h urinary sodium excretion (Salt24, g/day) and BP during sleep in young subjects. The subjects were 132 medical students (93 males, 39 females) aged 21 to 26 years, with no renal disorder. Urine was collected for 24 h, and sodium (Na), chloride (Cl), and creatinine (Cr) excretion were measured. The 24-h urinary Cr excretion (Cr24) was compared with the Cr24 estimated from lean body mass as a guide to ensure accurate collection of 24-h urine. The natural logarithm [ln (Salt24/Cr24)] was taken as an index of sodium intake. On the same day, a portable multi-biomedical recorder (TM2425) was used to measure 24-h systolic BP (SBP)/diastolic BP (DBP). Daytime BP was calculated as the average of waking-time BP, and sleep BP was taken as statistical base BP (minimum BP) during nighttime sleep. No correlation was observed between ln (Salt24/Cr24) and daytime BP. The correlation coefficient with sleep SBP, on the other hand, was 0.34 (p<0.05) in the male group and 0.54 (p<0.01) in the male high-BP group (24-h BP>127/75 mmHg, n=28). No relation of this kind was observed in the female group. In conclusion, despite the small number of subjects, the present cross-sectional study revealed a significant positive correlation between sodium intake and sleep SBP in young men with high BP.

Adult↗

PubMed2003

Japanese society of hypertension (JSH) guidelines for self-monitoring of blood pressure at home.

UNLABELLED: Home blood pressure (BP) measurements are indispensable for the improvement of hypertension management in medical practice as well as for the recognition of hypertension in the population. The Working Group for Establishment of Guidelines for Measurement Procedures of Self-Monitoring of Blood Pressure at Home of the Japanese Society of Hypertension has established standards for all techniques and procedures of home BP measurements. The recommendations are as follows. RECOMMENDATION: 1) Arm-cuff devices based on the cuff-oscillometric method that have been validated officially, and the accuracy of which has been confirmed in each individual, should be used for home BP measurement. 2) The BP should be measured at the upper arm. Finger-cuff devices and wrist-cuff devices should not be used for home BP measurements. 3) Devices for home BP measurement should be adapted to the American Association for Medical Instrumentation (AAMI) standards and the British Hypertension Society (BHS) guidelines. In addition, the difference between the BP measured by the auscultatory method and that measured using the device should be within 5 mmHg in each individual. The home measurement device should be validated before use, and at regular intervals during use. 4) Home BP should be monitored under the following conditions. The morning measurement should be made within 1 h after waking, after micturition, sitting after 1 to 2 min of rest, before drug ingestion, and before breakfast. The evening measurement should be made just before going to bed, sitting after 1 to 2 min of rest. 5) Home BP should be measured at least once in the morning and once in the evening. 6) All home BP measurements should be documented without selection, together with the date, time, and pulse rate. Use of devices with a printer or an integrated circuit memory is useful to avoid selection bias. 7) The home BP in the morning and that in the evening should be averaged separately for a certain period. The first measurement on each occasion should be used for totaling. 8) Home BP values averaged for a certain period indicate hypertension when 135/80 mmHg and over and definite hypertension when 135/85 mmHg and over. Normotension is defined as less than 125/80 mmHg and definite normotension as less than 125/75 mmHg. Home BP measurements based on these guidelines can be considered an appropriate tool for clinical decision-making, and it is hoped that these guidelines will serve to reduce confusion and confirm the place of home BP measurement in clinical practice.

Blood Pressure↗

PubMed2003

Relation between the timing of the last preinfarction angina and microvascular reperfusion in patients with recanalized acute myocardial infarction.

In patients with recanalized acute myocardial infarction (AMI), the relation between the timing of preinfarction angina (PA) and microvascular reperfusion remains unclear. A total of 186 patients (114 with anterior and 72 with inferior AMI) who had total occlusion and TIMI 3 recanalization < or = 6 hours from the onset of AMI were divided into 4 groups according to the time interval between the last episode of PA and the onset of AMI: < or = 2 hours (group A, n = 52); 2 to 48 hours (group B, n = 43), > or = 48 hours (group C, n = 33), and no PA (group D, n = 58). The angiographic myocardial blush grade, a marker of microvascular reperfusion, was retrospectively assessed immediately after recanalization. There were no differences in baseline characteristics, except for sex among the 4 groups. Myocardial blush grade 3 was more frequent (42% vs 21%, 9%, and 14%) and peak creatine kinase was lower (2659 vs 3455, 4422, and 4622 mU/mL) in group A than in groups B, C, and D (all P < 0.05). Multivariate analysis showed that PA occurring < or = 2 hours before AMI (OR 3.88, P < 0.05), a smaller summed ST-segment elevation before recanalization (OR 0.84, P < 0.01), earlier time to recanalization (OR 0.52, P < 0.05), and interior AMI (OR 4.87, P < 0.05) were independently associated with adequate microvascular reperfusion. We conclude that PA < or = 2 hours before the onset of AMI is independently associated with adequate microvascular reperfusion after recanalization in patients with AMI.

Adult↗

PubMed2003

[Quantitative analysis of the demand for emergency medicine in Yokohama City, Japan].

PURPOSE: We analyzed regional characteristics that potentially might affect regional demand for emergency medicine in Yokohama city and projected the number of future ambulance users. METHODS: The number of patients transported by ambulance was regarded as an index of the demand for emergency medicine. Various factors that may affect regional demand for emergency medicine were used as dependent variables in multiple regression analysis. The future population was estimated by the cohort change rate method based on the 1995 and 2000 censuses. Data pertaining to ambulance use were obtained from the Annual Fire Fighting Bulletin, Yokohama. Data pertaining to regional factors were obtained from the Annual Health Statistics Report, Yokohama; the Annual Health Statistics Report, Kanagawa; and the Statistics Report, Yokohama. RESULTS: Statistically significant relations were observed between ambulance use per 1000 population and particular regional characteristics, i.e. the proportion of persons undergoing health examinations conducted by public health centers, the number of educational health promotion programs managed by the public sector, the proportion of persons in receipt of livelihood protection, the proportions of roads and commercial areas in each district in relation to the total area, the mean land price, the age-adjusted mortality rate, and the proportion of persons aged 65 years or over. The demand for emergency medicine in Yokohama city was predicted to increase dramatically as the population ages. The number of patients transported by ambulance, which was 121,606 in 2000, was projected to exceed 250,000 in 2030 and to approximate 300,000 in 2050. CONCLUSION: The demand for emergency medicine will increase dramatically in Yokohama city as the society ages, Regional emergency medical systems should be improved accordingly.

Ambulances↗

PubMed2002

First report of CRF03_AB recombinant HIV type 1 in injecting drug users in Ukraine.

It has been reported that subtypes A throughout H of HIV-1 are circulating in the former Soviet Union. In this sequence note, we analyzed the genetic prevalence of HIV-1 among injecting drug users (IDUs) in Ukraine. The subjects studied included two individuals from Kiev and six individuals from Simferopol', the latter located in the Crimean Peninsula. We found that one of eight IDUs was infected with a CRF03 gagA/envB recombinant HIV-1 and was from Simferopol', whereas the others were infected with HIV-1 subtype A. There combinant was closely related to other A/B recombinants reported previously, and had silent mutations Inthe V3 region, the same as other envB strains of HIV-1 circulating among mDUs in the former Soviet Union. The data supported reports that the Russian AIB recombinant HIV-1 was probably from Ukraine. This is the first report of a CRF03 gagA/envB recombinant HIV-1 found in Ukraine.

Amino Acid Sequence↗

PubMed2002

Reliability of resolution of ST-segment elevation after coronary reperfusion in predicting myocardial salvage in anterior wall acute myocardial infarction.

Resolution of ST-segment elevation (ST resolution) after reperfusion therapy has been shown to correlate with improved left ventricular (LV) function in patients with acute myocardial infarction (AMI). However, not all patients with ST resolution have preserved LV function. We evaluated the clinical significance of ST resolution in 129 patients with anterior wall AMI who underwent successful coronary recanalization within 6 hours after symptom onset by studying the relation to myocardial blush grade, another angiographic marker of myocardial reperfusion. A reduction of > or =50% in ST-segment elevation after recanalization was defined as ST resolution. Ninety-eight patients had ST resolution and 31 patients did not. Patients with ST resolution were subdivided into 2 groups according to myocardial blush grade after recanalization: 67 patients with blush grade 2 or 3, and 31 with blush grade 0 or 1. The QRS score after recanalization was higher (5.9 +/- 1.9 vs 3.4 +/- 2.0, p <0.01) and predischarge LV ejection fraction was lower (39 +/- 8% vs 57 +/- 9%, p <0.01) in patients with blush grade 0 or 1 than in those with blush grade 2 or 3. However, the QRS score after recanalization and the predischarge LV ejection fraction were similar in patients who had ST resolution with blush grade 0 or 1 and in those without ST resolution. Our findings suggest that ST resolution after recanalization does not consistently predict myocardial salvage in patients with anterior AMI.

Adult↗

PubMed2002

Prevalence of constipation in continuous ambulatory peritoneal dialysis patients and comparison with hemodialysis patients.

Many hemodialysis patients suffer from constipation. The frequency of constipation has not been rigorously evaluated in continuous ambulatory peritoneal dialysis (CAPD) patients, however. We conducted a survey on constipation in CAPD patients and compared the findings with those in hemodialysis patients through a questionnaire. Daily dietary fiber and potassium intake were calculated from the patients' dietary records. In the questionnaire, patients were asked about bowel frequency, stool consistency, straining, and use of laxatives and resins. The frequency of constipation was 28.9% in 204 CAPD patients and 63.1% in 268 hemodialysis patients. The hemodialysis patients had a 3.14 times higher relative risk of constipation than the CAPD patients. Only 3.4% of CAPD patients needed resin to avoid hyperkalemia. Of hemodialysis patients, 49% needed resin. Among the 261 hemodialysis patients, 205 (78.5%) suppressed an urge to defecate during hemodialysis therapy. Potassium and total dietary fiber intake per day were 1.8 +/- 0.5 g and 11.0 +/- 4.0 g in CAPD patients, which were higher (P < 0.01) than the values in hemodialysis patients--1.3 +/- 0.5 g and 5.9 +/- 2.7 g. The results suggest that constipation occurs less frequently in CAPD patients than in hemodialysis patients. The low rate of constipating drug administration, dialysis modality-based lifestyle, and higher total dietary fiber intake may cause the lower prevalence of constipation in CAPD patients.

Adult↗

PubMed2002

Estimation of 24-h urinary sodium excretion using lean body mass and overnight urine collected by a pipe-sampling method.

UNLABELLED: BACKGROUND Although salt intake can be estimated from 24-h urinary sodium excretion (Na24 ), for a long time there has been no precise and easy method for its measurement. OBJECTIVE: To investigate the possibility of estimating Na24 using pipe-sampling of overnight urine and lean body mass. PARTICIPANTS AND METHODS: Body height, body weight and body fat determined by bioelectrical impedance (lean body mass = body weight body fat) was measured in 351 healthy individuals (126 men, 225 women). Twenty-four-hour urine was collected and creatinine and sodium were measured. To predict 24-h urinary creatinine excretion (Cr24 ), the relationship between Cr24 and lean body mass was investigated. Both 24-h urine and overnight urine specimens were collected in 149 individuals (71 men, 78 women) using a sampling pipe (semi-automatic proportional urine sampling device; height 16 cm, width 1.5 cm). Multiple regression analysis was used to estimate Na24. RESULTS: The prediction of Cr24 (Pr.UCr24 ) was derived from lean body mass. Using Pr.UCr24 and the overnight urinary Na/Cr excretion ratio (Na n /Cr n ), Na24 was estimated as 0.634 (Na n /Cr n ) Pr.UCr 24 + 104.7 mmol/day for men and 0.682 (Na n /Cr n ) Pr.UCr 24 + 62.6 mmol/day for women. The correlation coefficient (r) between true Na24 and Na24 estimated by these formulae was r = 0.78 ( P<0.001; mean difference SD-0.03 39.0 mmol/day). CONCLUSIONS: A new pipe-sampling method using overnight urine and lean body mass was easy and reliable for the estimation of Na 24. Furthermore, this method is convenient and may enable counselling on salt intake.

Adult↗

PubMed2002

Estimation of myocardial cell damage on the basis of mean electrocardiographic voltage and anatomical left ventricular mass.

Left ventricular mass (LVM) as assessed by magnetic resonance imaging (MRI, LVM(MRI)) and electrocardiographic (ECG) voltage reflect different pathological features. We hypothesized that ECG voltage is related to the electrical potential of cardiac muscle cells (electrical LVM) and to anatomical LVM as evaluated by MRI, and that the divergence between electrical LVM and anatomical LVM reflects the degree of myocardial damage. Because adipose tissue has high electrical resistance, we previously found a very strong correlation between body-fat-corrected mean ECG voltage (Vfm) and LVM as estimated by echocardiography in patients with essential hypertension. In this study we compared LVM(MRI), Vfm, the ratio of Vfm x 10(2)/LVM(MRI), and the results of 99mTc tetrofosmin scintigraphy in patients with and without myocardial infarction (MI). We studied 33 patients without Ml and 26 patients with Ml. Vfm significantly correlated with LVM(MRI) in patients without MI (r=0.71, p<0.01). The ratio of Vfm x 10(2)/LVM(MRI) apparently reflected the relation between electrical LVM and anatomical LVM. Vfm x 10(2)/LVM(MRI) in patients with MI was smaller than that in patients without MI (0.98+/-0.28 vs. 1.42+/-0.29, p<0.01). Vfm x 10(2)/LVM(MRI) decreased as 99mTc score increased (r=-0.66, p<0.01). Our results indicate that Vfm is a useful index of electrical LVM and that Vfm x 10(2)LVM(MRI) reflects the electrical potential of the viable myocardium in total anatomical LVM.

Aged↗

PubMed2002

[A review of methods for controlling medical costs from the point of view of cost-effectiveness].

Cost-effectiveness analysis is a method used to evaluate the outcomes and costs of treatments or interventions designed to improve health. It has been widely regarded as an important aid to providing health care services efficiently. This paper reviews several measures for controlling medical costs in Japan, where a fee-for-service system is employed to remunerate for medical services provision. From the point of view of cost-effectiveness, the first step in health care reform for controlling medical costs should be minimizing useless medical services because the cost-effectiveness ratio of these tends to infinity. For the purpose of minimizing unserviceable provision in the field of medicine, two approaches must be considered. One is establishing a system so that physicians can act as perfect agencies for their patients. The other is encouraging academic research on the effectiveness of medical services.

Cost Control↗

PubMed2002

[Relationship between activities of daily living and residential environment for patients receiving home oxygen therapy].

PURPOSE: The purpose of this study was to investigate the relationship between ADL and residential environment for patients receiving home oxygen therapy. METHODS: We interviewed 27 HOT patients with chronic respiratory failure, aged 53-85, at an internal medicine outpatient clinic of a national hospital in Yokohama city, using a questionnaire focusing on physical condition, dyspnea, ADL, and residential environment. RESULTS: 1. Of the patients 21 (78%) were III-IV level by Hugh-Jones classification. HOT patients experienced severe dyspnea when climbing stairs and bathing. Their ADL was limited to within their own homes. HOT patients opt to use taxies more often than facilities such as buses and trains. 2. Out of 20 patients living in a two-story house, the ADL of 16 (80%) were limited to downstairs. Two patients living in apartment houses without an elevator complained of great difficulties in going down stairs to go out. Twelve of the patients (44%) interviewed resided in hillside area, the distance to the nearest bus stop being greater than in flat area. 3. A public financial support for house innovation has been offered for some time, but most of the patients did not have any information about this system. They had not realized how their residential environment might affect their ADL. CONCLUSION: These results suggest that more education for HOT patients is needed. They should be clearly shown the importance of the residential environment in enhancers their ADL.

Activities of Daily Living↗

PubMedDate not supplied

Implication of base heart rate in autonomic nervous function, blood pressure and health-related QOL.

Increased resting heart rate (HR) and increased sympathetic nervous activity are independent risk factors for cardiovascular disease. Recently, base heart rate (HRo: minimum stable HR during sleep) has been reported to relate to cardiac stroke volume and age. However, little is known about the relevance of HRo. The aim of our study was to evaluate how HRo is associated with HR variability (HRV), blood pressure and health-related quality of life (HRQOL) in healthy subjects. A total of 139 volunteers participated in this study that measured 24-hr HR, HRV, and blood pressure. HRo was estimated from the trendgram and the histogram of HR during the nighttime (sleep) period, and calculated as the 1% lowest value of its integral. HRQOL was assessed by Medical Outcome Study Short-Forum 36-Item Health Survey. Sympathetic nervous activity (ratio of low frequency to high frequency component: LF/HF) and parasympathetic nervous activity (high frequency component: HF) were calculated by ECG monitoring. HRo was positively correlated with 24-hr LF/HF and nighttime LF/HF. HRo was negatively correlated with 24-hr HF and nighttime HF. Moreover, HRo was positively correlated with the scores of social functioning and role-physical. Using multivariate analysis, HRo is related to LF/HF, body mass index, and the score of social functioning (HRQOL). HRo may be a useful indicator for assessing sympathetic nervous activity and HRQOL in normotensive healthy subjects.

Adult↗

PubMedDate not supplied

Development of wristwatch-type heart rate recorder with acceleration-pickup sensor and its application.

We have developed a wristwatch-type heart rate (HR) recorder (WT-HR tachometer) with an acceleration-pickup sensor, which can record HR and body activity (ACT) minute by minute for a long time (> 120 h). To study its application, we compared these measurements with 24-h blood pressure (BP) and HR variability, sympathovagal balance, and resting energy expenditure (REE). The WT-HR tachometer incorporates a Seiko-blue sensor to measure HR at the wrist and an acceleration-pickup sensor to measure body ACT every 4 sec. Fifty healthy university students underwent measurement of HR and ACT by the WT-HR tachometer for 24 h. Then we calculated the minimum HR and mean HR during waking time and derived deltaHR. On the same day, 24-hr BP and LF/HF (low frequency component/high frequency component of ECG-RR interval power spectrum) were measured with a multibiomedical recorder, and REE was measured with a portable calorimeter. The WT-HR tachometer accurately measured HR, compared with the measurements by Holter-ECG. There was a significant correlation between deltaHR and deltaSBP. There also was a significant correlation between deltaHR and deltaLF/HF, (waking time = waking time without body movement) and a significant correlation between HR and REE. These results suggest that ACT and deltaHR are useful for evaluating mental and physical activity of daily life. The WH-HR tachometer will be useful for assessment of mental and physical activity in daily life.

Adult↗

PubMedDate not supplied

Ring-shaped pulse oximeter and its application: measurement of SpO2 and blood pressure during sleep and during flight.

Respiratory and cardiovascular functions show circadian and day-to-day changes. We have developed a wireless ring-shaped pulse oximeter in collaboration with MC Medical Inc. and Advanced Medical Inc. We investigated the accuracy of this pulse oximeter and its application in daily life. Percutaneous arterial oxygen saturation (SpO2) of 47 volunteers was measured simultaneously with the ring-shaped pulse oximeter and a standard pulse oximeter. A total of 103 volunteers underwent measurement of SpO2 for 24 hr, and 11 healthy volunteers underwent measurement of SpO2 and blood pressure (BP) during flight. SpO2 and heart rate (HR) were measured and recorded every 20 sec, cabin barometric pressure and cabin oxygen concentration equivalent to sea level were measured minute-to-minute, and BP was measured every 3 min with a portable BP recorder during each flight. The SpO2 values measured with the ring-shaped pulse oximeter were similar to those measured with the standard method. The mean SpO2 during sleep was significantly lower in the group with high-normal BP or mild hypertension than in the group with normal BP. During flight, the mean change in SpO2 was -2.4 +/- 1.7% during nose-up flight, and 2.1 +/- 2.6% during nose-down flight. There was a significant correlation between change in SpO2 and change in systolic BP during nose-up flight. The wireless ring-shaped pulse oximeter was useful for investigating changes in SpO2 and its effect on BP in daily life during sleep and during air travel.

Adolescent↗