Epidemiological studies of the effects of heat wave have made it possible to identify at-risk populations: the elderly or those with cardiovascular disease, diabetes, or a neuropsychiatric affliction treated by neuroleptic. All of these populations are frequently under a variety of drug treatments that can influence their thermoregulation.

Even though the human body does have the physiological means for fighting excessively-high environmental heat, this ability is impaired in at-risk populations. One of the ways in which the body fights is to vary blood circulation in the skin (in conjunction with sudation), which makes it possible to regulate the heat lost by the body. This study of how ageing and medicines frequently used on the elderly affect cutaneous blood circulation should enable better drug prescription. This can mean changing dosage or discontinuing dangerous treatments should a heat wave alert or forecast be issued, as this would have side effects on thermoregulation. For this purpose, we propose:

1. A clinical approach:

Vasodilatation of cutaneous blood vessels facilitates heat exchanges between the internal environment and the external environment and contributes to regulating body temperature. A test has been designed in our laboratory on cutaneous vasomotricity in response to stimulation by a low-intensity Galvanic current. Moreover, we know how to measure dependent endothelium vasodilatation, using a Doppler laser flow-meter and iontophoresis. We propose to study the effects of platelet anti-aggregants, both antipyretic and non-antipyretic, on cutaneous vasodilatation in healthy and elderly subjects. This study will make it possible to modify prescriptions for this treatment.

2. A multi-disciplinary think-tank network:

A first symposium was held last year and included a range of parties involved in work on thermoregulation. We plan to hold another symposium, to forward the launch of the think-tank network and bring together knowledge and thinking from different fields involved in managing the effects of heat wave.

Expected outcomes:

1. To determine whether taking platelet antiaggregants, some of which are also antipyretics, can change the effects of the heat wave in healthy subjects.

2. To determine whether, in elderly subjects, such medicines, which are prescribed chronically, could modify the deleterious effects of the heat wave. This study will thus help issue guidelines so as to adapt treatment when a risk of heat wave is announced. Drug treatment, often prescribed to prevent atherosclerosis or thrombosis risk, could often be discontinued temporarily, until such time as the weather becomes more favourable.

3. To continue discussion about the physiopathological effects of the heat wave with the few teams involved in such work.