Heatstroke management during the COVID-19 epidemic: recommendations from the experts in Japan

Heatstroke-related ambulance dispatch risk before and during COVID-19 pandemic: Subgroup analysis by age, severity, and incident place

BACKGROUND

In summer 2020 under the COVID-19 pandemic, the Ministry of Health, Labour and Welfare has made public warnings that specific preventive measures such as maskwearing and stay-at-home orders, may increase heatstroke risk. In our previous work, we found a lower risk of heatstroke-related ambulance dispatches (HSAD) during the COVID-19 period, however, it is uncertain whether similar risk reductions can be observed in different vulnerable subgroups. This study aimed to determine the HSAD risk during the COVID-19 pandemic by age, severity, and incident place subgroups.

METHOD

A summer-specific (June-September), time-series analysis was performed, using daily HSAD and meteorological data from 47 Japanese prefectures from 2017 to 2020. A two-stage analysis was applied to determine the association between HSAD and COVID-19 pandemic, adjusting for maximum temperature, humidity, seasonality, and relevant temporal adjustments. A generalized linear model was utilized in the first stage to estimate the prefecture-specific effect estimates. Thereafter, a fixed effect meta-analysis in the second stage was implemented to pool the first stage estimates. Subsequently, subgroup analysis via an interaction by age, severity, and incident place was used to analyze the HSAD risk among subgroups.

RESULTS

A total of 274,031 HSAD cases was recorded across 47 Japanese prefectures. The average total number of HSAD in the pre-COVID-19 period was 69,721, meanwhile, the COVID-19 period was 64,869. Highest reductions in the risks was particularly observed in the young category (ratio of relative risk (RRR) = 0.54, 95% Confidential Interval (CI): 0.51, 0.57) compared to the elderly category. Whereas highest increment in the risks were observed in severe/death (RRR = 1.25, 95% CI: 1.13, 1.37) compared to the mild category.

CONCLUSION

COVID-19 situation exhibited a non-uniform change in the HSAD risk for all subgroups, with the magnitude of the risks varying by age, severity, and incident place.

Wearing a face mask during controlled-intensity exercise is not a risk factor for exertional heatstroke: A pilot study

Aim

This study aimed to measure the influence of wearing face masks on individuals' physical status in a hot and humid environment.

Methods

Each participant experienced different physical situations: (i) not wearing a mask (control), (ii) wearing a surgical mask, (iii) wearing a sport mask. An ingestible capsule thermometer was used to measure internal core body temperature during different exercises (standing, walking, and running, each for 20 min) in an artificial weather room with the internal wet-bulb globe temperature set at 28°C. The change in the participants' physical status and urinary liver fatty acid-binding protein (L-FABP) were measured.

Results

Six healthy male volunteers were enrolled in the study. In each participant, significant changes were observed in the heart rate and internal core temperatures after increased exercise intensity; however, no significant differences were observed between these parameters and urinary L-FABP among the three intervention groups.

Conclusion

Mask wearing is not a risk factor for heatstroke during increased exercise intensity.

Evaluation of the physiological changes in prehospital health-care providers influenced by environmental factors in the summer of 2020 during the COVID-19 pandemic

Aim

Wearing personal protective equipment (PPE) is essential to prevent infection transmission, but the risk of heatstroke increases with wearing PPE in a humid and hot environment. Therefore, we aimed to examine how environmental parameters change the body physiology in a hot environment during the coronavirus disease (COVID-19) pandemic.

Methods

This was a retrospective cohort study extracted from the MEDIC Japan heatstroke prevention database, which was recorded between 1 August and 7 September, 2020. Its database is a registry collection from seven healthy health-care providers. Subjects recorded their own vital signs (forehead and tympanic temperature, blood pressure, pulse rate, and oxygen saturation) and environmental factors (type of weather, wet-bulb globe temperature [WBGT], air temperature, humidity, and location) every hour during their working shift.

Results

From 323 records, a weak positive but statistically significant correlation was observed between WBGT and pulse rate (correlation coefficient [95% confidence interval], r = 0.34 [0.23, 0.45]) and between WBGT and core body temperature. Forehead temperature had a stronger correlation than tympanic temperature (forehead, r = 0.33 [0.21, 0.43]; tympanic, r = 0.17 [0.05, 0.28]), which also showed a larger effect (forehead, η² = 0.08; tympanic, η² = 0.05). The effect size of oxygen saturation measured outdoors was large (η² = 0.30). Forehead temperature increased abruptly at 28°C WBGT and at 33°C air temperature.

Conclusion

A hot environment significantly affected forehead temperature, and the daytime imposed a high risk of heatstroke. To avoid heatstroke, environmental parameters are important to note as outdoor environments had a large effect on vital sign changes depending on the time of day.

Trends in emergency transportation due to heat illness under the new normal lifestyle in the COVID-19 era, in Japan and 47 prefectures

In Japan, in response to the spread of the new coronavirus disease (COVID-19), a 'new normal' in the era of the COVID-19 was proposed by the government, which calls for thorough wearing of masks as an infection control measure in the era of the COVID-19, but related heat illness has been a great concern this summer. We applied quasi-Poisson regression models to the daily number of emergency transportations due to heat illness from 2008 to 2020 from the Fire and Disaster Management Agency, Ministry of Internal Affairs and Communications, Japan, to estimate the expected weekly number of emergency transportations from heat illness, with adjustment for their long-term trend and the weather conditions, including temperatures. We found that, at the national level, the number of heat illness emergency transports did not significantly increase or decrease from the annual trend in 2020. By prefecture, on the other hand, there were some prefectures in which the number of heat illness emergency transports was less than the average year, and most of them were in the week of August 10-16. By age group, the number of heat illness emergency transports in the 0-17 and 18-64 age groups was particularly low in some prefectures, and by severity, those in mild cases was particularly low. A caution is necessary that there is a possibility that a decrease in cases possibly associated with COVID-19 measures, such as, outdoor activity restrictions at schools/universities and cancellation of public events, may offset the possible increase in heat illness cases occurring elsewhere associated with wearing masks. Given that the end of the COVID-19 pandemic is not expected yet, continuous and appropriate awareness-raising activities to prevent heat-related illness remain important.

COVID-19 and Heat Illness in Tokyo, Japan: Implications for the Summer Olympic and Paralympic Games in 2021

The 2020 summer Olympic and Paralympic Games in Tokyo were postponed to July-September 2021 due to the coronavirus disease 2019 (COVID-19) pandemic. While COVID-19 has emerged as a monumental health threat for mass gathering events, heat illness must be acknowledged as a potentially large health threat for maintaining health services. We examined the number of COVID-19 admissions and the Tokyo rule for emergency medical care, in Tokyo, from March to September 2020, and investigated the weekly number of emergency transportations due to heat illness and weekly averages of the daily maximum Wet Bulb Globe Temperature (WBGT) in Tokyo in the summer (2016-2020). The peak of emergency transportations due to heat illness overlapped the resurgence of COVID-19 in 2020, and an increase of heat illness patients and WBGT has been observed. Respect for robust science is critical for the decision-making process of mass gathering events during the pandemic, and science-based countermeasures and implementations for COVID-19 will be warranted. Without urgent reconsiderations and sufficient countermeasures, the double burden of COVID-19 and heat-related illnesses in Tokyo will overwhelm the healthcare provision system, and maintaining essential health services will be challenging during the 2021 summer Olympic and Paralympic Games.