The relationship between home blood pressure measurement and room temperature in a Japanese general population

Associations of indoor and outdoor temperatures and their difference with home blood pressure: The Masuda Study

Ambient temperature and blood pressure (BP) are closely related; however, few studies have examined the association of out-of-office BP with indoor or outdoor temperature. The effect of the difference between indoor and outdoor temperatures on BP also remains unknown. Therefore, this study aimed to investigate the association of indoor and outdoor temperatures and their difference with home BP. We studied healthy 352 participants (mean age, 49.8 years; 46.0% women) from a population-based cohort using 2-year data on temperature and self-measured home BP. We measured home BP and indoor temperature at the same time in the morning and evening every day. Outdoor temperature during the same period was based on national data. We observed 82,900 home BP measurements in the morning and 66,420 in the evening. In the mixed-effects model adjusted for age, sex, and possible confounders, indoor temperature was inversely associated with systolic and diastolic BP in the morning and evening. A 1 °C increase in indoor temperature reduced systolic and diastolic BP by 0.37 and 0.22 mmHg, respectively, in the morning and by 0.45 and 0.30 mmHg, respectively, in the evening (all P-values<0.001). The magnitude of associations was stronger for indoor than outdoor temperature. Similarly, a 1 °C increase in indoor temperature above outdoor temperature decreased systolic and diastolic BP by 0.33 and 0.12 mmHg, respectively, in the morning and by 0.45 and 0.26 mmHg, respectively, in the evening independent of outdoor temperature (all P-values <0.001). In conclusion, controlling indoor temperature is important to stabilize home BP levels.

Morning surge in sympathetic nervous activity in the indoor environment during the cold winter season

We addressed to the sympathetic nervous activation of the same people in both their houses and a highly insulated and airtight model house (model house) during the cold winter season. Eight subjects (4 males and 4 females) stayed two nights at each house and were continuously monitored for sympathetic nerve system by calculating LF (low frequency)/HF (high frequency) in the analysis of heart rate variability using a wearable electrocardiography equipment. The room temperatures were kept constant at 20 °C or more in model house, but much lower in their houses. In all subjects, the sleeping duration is longer in model house compared with that in the participants' houses. Four subjects showed a morning surge in sympathetic activity that were more intense at their houses. This morning surge in sympathetic activity in a residential setting suggests the importance of the indoor environment in the management of early morning hypertension.

Seven-action approaches for the management of hypertension in Asia - The HOPE Asia network

Asia is a large continent and there is significant diversity between countries and regions. Over the last 30 years, absolute blood pressure (BP) levels in Asia have increased to a greater extent than those in other regions. In diverse Asia‐Pacific populations, for choosing an Asia‐specific approach to hypertension management is important to prevent target organ damage and cardiovascular diseases. In this consensus document of HOPE Asia Network, we introduce seven action approaches for management of hypertension in Asia.

Feasibility of Low-Sodium, High-Potassium Processed Foods and Their Effect on Blood Pressure in Free-Living Japanese Men: A Randomized, Double-Blind Controlled Trial

We aimed to verify the effect of new low-sodium high-potassium seasonings and processed foods containing poly-γ-glutamic acid on blood pressure in free-living settings. To this end, we conducted a randomized, double-blind controlled trial on 187 Japanese men, aged 35–67 years, who did not use antihypertensives. Participants were randomly allocated to an intervention (n = 93) or a control group (n = 94). They were given a boxed lunch and miso soup (average Na and K content for the intervention group: 1175 and 1476 mg; for the control group: 2243 and 703 mg, respectively). Blood pressure was measured three times every morning for 1 week immediately before and during the final week of the trial. On the day before and the final day of the intervention period, 24 h urine samples were collected. After intervention, the intervention group showed a significantly stronger decrease in the urinary sodium-to-potassium ratio than the control group (p < 0.001). The mean difference in systolic blood pressure change after adjustment for baseline values between the two groups was −2.1 (95% CI: −3.6, −0.6) mmHg. Compliance between the groups was similar, suggesting successful blinding. In conclusion, the use of new seasonings and processed foods aimed at lowering blood pressure in free-living settings may be feasible and effective.

Impact of indoor temperature instability on diurnal and day-by-day variability of home blood pressure in winter: a nationwide Smart Wellness Housing survey in Japan

Home blood pressure (HBP) variability is an important factor for cardiovascular events. While several studies have examined the effects of individual attributes and lifestyle factors on reducing HBP variability, the effects of living environment remain unknown. We hypothesized that a stable home thermal environment contributes to reducing HBP variability. We conducted an epidemiological survey on HBP and indoor temperature in 3785 participants (2162 households) planning to have their houses retrofitted with insulation. HBP was measured twice in the morning and evening for 2 weeks in winter. Indoor temperature was recorded with each HBP observation. We calculated the morning-evening (ME) difference as an index of diurnal variability and the standard deviation (SD), coefficient of variation (CV), average real variability (ARV) and variability independent of the mean (VIM) as indices of day-by-day variability. The association between BP variability and temperature instability was analyzed using multiple linear regression models. The mean ME difference in indoor/outdoor temperature (a decrease in temperature overnight) was 3.2/1.5 °C, and the mean SD of indoor/outdoor temperature was 1.6/2.5 °C. Linear regression analyses showed that the ME difference in indoor temperature was closely correlated with the ME difference in systolic BP (0.85 mmHg/°C, p < 0.001). The SD of indoor temperature was also associated with the SD of systolic BP (0.61 mmHg/°C, p < 0.001). The CV, ARV, and VIM showed similar trends as the SD of BP. In contrast, outdoor temperature instability was not associated with either diurnal or day-by-day HBP variability. Therefore, residents should keep the indoor temperature stable to reduce BP variability.