Abstract
4. Acknowledgements
Figure 10 Relationship between ventilation rate a person Qp and Index of influenza infection control Γ / relationship between index of influenza infection control Γ and absolute humidity and energy load of ventilation and humidification Lvh
The index Γ made it possible to estimate the state of infection control in indoor spaces using the measured temperatures, humidity and concentrations of carbon dioxide. The index Γ and the energy consumption for ventilation and humudification Lvh varied from space to space. These results showed that it is necessary to control both of ventilation rates and humidification rates on the basis of the estimation using Γ and Lvh.
Professor, Toshiharu Ikaga, Keio University, Japan, ikaga@sd.keio.ac.jp
Emeritus Professor, Tanji Hoshi, Tokyo Metropolitan University, Japan, star@onyx.dti.ne.jp Lecturer, Shintaro Ando, the University of Kitakyushu, Japan, s-ando@kitakyu-u.ac.jp
Abstract
Purpose / Context – To quantify the relationship between indoor temperature and blood pressure in Japanese nursing home residents.
Methodology / Approach – A field study of 27 nursing homes in Japan was conducted. We measured the indoor temperature of nursing homes and collected data on resident’s blood pressure via a standardised questionnaire. Facilities were classified into two groups based on measured indoor temperature. Blood pressure rise in winter was defined as the difference in blood pressure between January and August to minimise individual variation.
Results – Daytime and night-time indoor temperatures were significantly associated with blood pressure rise in winter, even after adjusting for the effects of potential confounders such as age, gender, body mass index, residential period, care level, systolic blood pressure in August, and medication in January. A 1°C decrease in the indoor room temperature was significantly associated with a 0.74 mmHg increase in the blood pressure rise in winter for daytime temperature (p < 0.01) and a 0.72 mmHg increase for night-time temperature (p < 0.01).
Key Findings / Implications – The association between indoor temperature and blood pressure that we found could contribute to controlling the blood pressure of residents by improving indoor thermal environments in nursing homes.
Originality – Our findings from this field study on residents in nursing homes expand the applicability of previous studies on the general population in real life situations and clarify the generalisability of experimental evidence about thermoregulation and blood pressure in controlled settings.
Keywords – Indoor Thermal Environment, Blood Pressure, Aged Care, Field Survey, Senior Liv- ing
Yukie Hayashi Graduate student Keio University Japan
Yukie1222@z2.keio.jp
1. Introduction
The ageing Japanese population has the world’s highest proportion of elderly people, and the num- ber of residents in nursing homes is increasing. High blood pressure is a risk factor in longer periods of care (Gohgi, 2005), and controlling the blood pressure of residents in nursing homes is important for care prevention. The effects of indoor thermal environment on blood pressure have been re- ported in previous studies. A large-scale field study on general dwelling house residents suggested that increases in blood pressure can be controlled with a warm indoor temperature in winter (Saeki, 2015 and 2014). Because the effects of temperature on blood pressure are greater in older people (Umishio, 2015 and 2014;
Lanzinger, 2014), conducting a survey for elderly nursing home residents is important. To quantify the association between indoor temperature and nursing home residents’ blood pressure, we conducted a field study among 27 nursing homes in Japan. We measured the indoor temperature of nursing homes and collected data on residents’ blood pressure through a standardised questionnaire.
2. Methodology
2.1 Participants
In winter and summer of 2015, field studies on the indoor thermal environment of nursing homes and resident’s blood pressure were conducted. The study included 1100 residents in 27 facilities located in Yamanashi, Nagano, Osaka, Nara, Hyogo, and Kyoto prefectures. The facilities were special nursing homes for the elderly, geriatric health service facilities, or pay nursing home.
2.2 Study protocol
The indoor temperatures in facilities were measured for approximately 4 weeks in January to February. Three facilities in Yamanashi prefecture also participated in measuring indoor temperatures from August to September. Information about residents’ was recorded by care staff using a stand- ardised questionnaire. The buildings’ characteristics, including building age, structure, insulation performance, and number of residents and staff, were recorded at the same time.
2.3 Indoor air temperature
Temperatures and relative humidity were measured at 20 min intervals 0.1 m and 1.1 m above the floor in private rooms, dining halls, corridors, and dressing rooms. These temperatures and relative humidity were measured by using Thermochron (KN laboratories) data loggers in Yamanashi prefecture and AD-5696 (A&D company) data loggers in other prefectures. The local meteorological office in each study area provided outdoor temperature data recorded at 10 min intervals.
2.4 Blood pressure and individual attributes
Because of the difficulties in presenting questionnaires to residents in nursing homes, standardised questionnaires were completed by care staff. The medical charts, average blood pressure, and use of antihypertensive drugs in January, March, August, and November were recorded for each resi- dent. Individual attributes, including age, gender, height, weight, duration at current residence, care requirements, seasonal blood pressure, and medication were recorded at the same time.
2.5 Statistical analysis
The 27 facilities were classified into two groups based on the room temperature recommended in Cold Weather Plan for England 2013 (Figure 1). The recommendation is as follows: “heat your home to the right temperature: your living room should be 21 °C (70 °F), and your bedroom and the rest of the house heated to 18 °C (65 °F)” (PHE, 2013). In this study, daytime was defined as 06:00 to 17:59, and night-time was defined as 18:00 to 05:59 the following day, based on the forecast phra- seology of the Japan Meteorological Agency. In this report, the temperatures measured 1.1 m above the floor were used for analysis. For continuous variables with a normal distribution, mean ± stand- ard deviation (SD) was reported. For variables with a skewed distribution, medians and interquartile ranges were reported. Mean and median values were compared by using a t-test. The proportions of both groups were compared by using the chi-squared test. Relationships between the indoor temperature and residents’ blood pressure were assessed by using multilevel analysis and multiple regression analysis. The applicability of multilevel analysis was verified by the intraclass correlation coefficient (ICC) and the design effect (DE) of the null model. If the ICC was over 0.10 and DE was over 2.0, the data were considered in its configuration. All p-values were two-sided, and p < 0.05 was considered statistically significant. All statistical analyses were performed with SPSS ver. 22.0 software.
Figure 1 Grouping rule based on Cold Weather Plan for England 2013 (PHE, 2013)