Too hot! Preventing, recognizing and managing heat injury in children

Abstract

Climate change-related extreme heat events leading to public health emergencies are increasing in Canada and expected to affect more regions, more frequently and for longer time periods. Children, city dwellers and marginalized populations are amongst the most vulnerable to morbidity and mortality related to extreme heat. Paediatricians can provide caregivers and families with advice to minimize risks as well as advocate for safer city planning and harm mitigation strategies.

Graphical Abstract

Graphical Abstract.

Climate change-related heat extremes are becoming more frequent and intense. Unprecedented high temperatures were recorded across Canada in 2021 (1), causing a public health emergency associated with 740 excess deaths in British Columbia. This phenomenon is expected to become the norm (2), increasing disproportionately in urban and suburban regions, resulting in disastrous health impacts that are most significant for vulnerable populations, particularly infants and children (3). Marginalized populations, including people with lower socioeconomic status, housing insecurity or who identify with equity-seeking groups, and people whose activities require them to be outdoors, are more likely to be vulnerable to morbidity and mortality from heat extremes as well as being at higher risk of experiencing increasing frequency and intensity of heat extremes in the future (3–5).

Children are less able to control their environment and less likely to maintain adequate hydration and thermoregulation than adults (4). Physiologic adaptation to increased ambient temperature, including control of fluid and electrolyte loss through increased aldosterone production and decreased electrolytes in sweat, increased cardiac output (stroke volume) and initiation of vasodilation and sweating at lower temperatures, is slower and less effective in infants and young children (4). Failure to maintain thermoregulation results in heat morbidity and mortality; as an example in Canada at least 6 paediatric deaths were attributable to vehicular entrapment from 2013 to 2018 (3,5).

Climate change is significantly increasing the length and severity of extreme heat events and the number of children and families exposed to risk for morbidity and mortality associated with heat exposure (3,4). Paediatricians and other healthcare providers for children need to be aware of risks, symptoms and management strategies for heat injuries and can provide patients, families and communities with preventive advice to minimize risk (Table 1).

Table 1.

Health risks associated with heat exposure (4)

Issue	Problem	Severity	Symptoms	Signs	Prevention	Treatment
Thermoregulation	Heat stress	Mild	Perceived discomfort	Normal vital signs	Limit heat exposure Seek cool or air-conditioned shelter Ensure adequate hydration Avoid strenuous exercise in extreme heat Infants, young children and teen athletes are at higher risk and should be carefully observed	Cool, hydrate
	Heat exhaustion	Moderate	Thirst, headache, weakness, dizziness, syncope, vomiting, dehydration	Core temperature <40°C Tachycardia, hypotension No central nervous system or end organ dysfunction		Cooling, rest
	Heat stroke	Severe Life-threatening	Neurologic dysfunction, altered mental status, hematemesis, hematochezia, purpuric rash + symptoms of heat exhaustion	Core temperature >40°C High output heart failure, hypotension, arrhythmia, pupil changes, tetany, liver and renal failure		Emergency medical care Immediate immersion in cold water, ongoing cooling. May require ventilatory support. Manage end organ damage
	Vehicular entrapment—can happen in moderate temperatures	Life-threatening	Heat stroke secondary to becoming trapped in a vehicle	Young children are particularly high risk	Prevention (5): back seat reminders, lock car so children can’t get in	As for heat stroke
Fluid and electrolyte loss	Dehydration	Variable	Thirst	Normal vital signs	Maintain adequate fluid intake	Adequate intake of fluids and electrolytes
Burns	Sunburn	Variable (2,6)	Erythema, heat, pain, swelling, blistering	Mostly superficial	Avoid sun exposure, use sunscreen	Prevention: shade, clothing coverage, sunscreen; oral agents under investigation (4,6)
	Thermal burn	Variable	Erythema, heat, pain, blistering, pallor or lack of pain are red flags for a full-thickness burn	Classify as superficial, partial- or full-thickness burn	Check surfaces that could be hot before exposing children	Prevention: check hot surfaces, including sand and pavement (2)
Other issues	Asthma exacerbation	Variable	Shortness of breath, cough, wheeze	Work of breathing, hypoxemia	Avoid extreme heat, always have reliever medication available	Asthma management
	Heat rash	Mild	Erythematous rash may be pruritic	Milaria, common in infants	Keep cool, avoid overdressing or bundling infants	Cool, light clothing Self-resolving
	Edema	Mild	Hand and foot swelling	Dependent edema	Keep cool	Cool, elevate affected dependent areas
	Exercise-associated muscle cramping	Mild	“Heat cramps” can occur with high-intensity exercise in heat and cold, more common with deconditioning, dehydration or poor acclimatization	Normal vital signs	Avoid strenuous or unaccustomed exercise on hot days and unfamiliar climates, ensure adequate hydration	Supportive; rest, hydration, cooling, stretching

Five things for paediatricians to tell their patients about extreme heat

1. Keep kids cool, in the shade, rest often and avoid strenuous exercise

2. Stay out of the sun, cover up or use sunscreen

3. Ensure good hydration

4. Never leave a child in a car or other closed environment; lock the car when it is not in use

5. If children are dizzy, confused or lose consciousness, it is an emergency

FUNDING

This work was not funded.

POTENTIAL CONFLICTS OF INTEREST

A.H. is a member of the editorial board. Another editor was assigned to handle the peer review of this manuscript. Outside the context of this manuscript, she also reports a CIHR Team Grant and a grant from the Lung Association of Alberta, as well as support from the American Thoracic Society and the Canadian Paediatric Society for travel costs. A.H. is also President of the Canadian Paediatric Society Section of Environmental Health and a Member of the American Thoracic Society Environmental Health Policy Committee. There are no other disclosures. Both authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.