Heat stroke (HS) is a serious and fatal disease caused by thermal injury factors acting on the body, and is the most severe type of severe heatstroke. Patients often develop symptoms due to an imbalance between thermogenesis and heat dissipation, characterized by an increase in core temperature greater than 40 ℃ and abnormalities in the central nervous system. The main symptoms include high fever, consciousness disorders such as convulsions and coma, accompanied by multiple organ damage. In severe cases, the condition can be life-threatening.
Clinical classification
Heat stroke is divided into exertional heat stroke (EHS) and non exertional heat stroke, the latter also known as classical heat stroke (CHS).
epidemiology
contagious
Non infectious.
incidence rate
The incidence rate of classical type heat stroke in summer is about (17.6~26.5) per 100000 people, and the proportion of labor type heat stroke in labor type heat induced diseases is 8.6%~18%.
mortality
The in-hospital mortality rate of classic heat stroke is 14% to 65%, the mortality rate of ICU patients is>60%, and the mortality rate of exertional heat stroke with hypotension is>30%. The mortality rate of patients over 50 years old is as high as 80%.
incidence trend
The incidence of heat stroke and the resulting deaths in our country are increasing year by year.
Easy to reach people
- Soldiers, athletes, firefighters, construction workers, etc. who participate in summer training.
- Individuals with impaired thermoregulatory function, such as infants and young children, elderly people, alcohol or drug addicts, pregnant women, patients with chronic underlying diseases, long-term bedridden and obese patients, etc.
- Patients with systemic sclerosis, extensive skin scars, or congenital anhidrosis.
cause of disease
executive summary
Under normal circumstances, the hypothalamic thermoregulatory center of the human body maintains a relatively stable body temperature by controlling heat production and dissipation based on the external environment. Long term exposure to hot environments and/or intense exercise can lead to an imbalance between heat production and dissipation in the body, resulting in heat stroke.
underlying cause
- Increased heat generation
The main source of heat production in the human body comes from oxidative metabolism processes. During intense exercise, the amount of heat produced increases by 20 times compared to the resting state. For example, people who engage in physical labor, exercise, and military training have significantly increased body heat production; Fever, chills, tremors, sepsis, convulsions, hyperthyroidism, sympathomimetic drugs (such as amphetamines and ergotamine) can also cause the body to produce heat, raise body temperature, and easily trigger heatstroke.
- Get more heat
When the ambient temperature rises, some elderly, weak, and sickly individuals may experience impaired temperature regulation and reduced ability to adjust their body temperature at will, resulting in an increase in the amount of heat the body obtains from the environment and leading to heatstroke.
- Heat dissipation obstacle
(1) Reduced sweating: Dysfunction or loss of sweating and heat dissipation. If not careful to avoid high heat environments, it is prone to heatstroke, commonly seen in patients with extensive skin burns, scar formation, scleroderma, congenital sweat gland deficiency, and cystic fibrosis.
(2) Reduced central nervous system reactivity: seen in individuals with brain or hypothalamic dysfunction, those taking sedatives and hypnotics, the elderly, infants and young children, and drinkers.
(3) Reduced cardiovascular reserve function: seen in elderly people, those with heart dysfunction, insufficient blood volume, dehydration, and those who use beta blockers, calcium blockers, and diuretics.
(4) Application of drugs that affect sweating, such as anticholinergic drugs and antihistamines.
(5) External factors: high temperature and high humidity environment.
(6) Other: excessive obesity and poor breathability of clothing.
symptom
executive summary
Heat stroke is characterized by an increase in core temperature, exceeding 40 ℃. Patients often have central nervous system abnormalities, such as changes in mental state, delirium, convulsions, or coma. In severe cases, there may be multiple organ damage manifestations.
Typical Symptoms
- Exertional heat stroke
Commonly seen in healthy young people (such as officers and soldiers participating in training), after high-intensity training or heavy physical labor in a high temperature and high humidity environment for a period of time, they suddenly feel discomfort, fever, headache, dizziness, slow reaction, or suddenly faint, lose consciousness, accompanied by nausea, vomiting, shortness of breath, etc., and then their body temperature rapidly rises to over 40 ° C, resulting in delirium, drowsiness, and coma. Dry and hot skin, flushed or pale complexion, starting to sweat profusely or coldly, then turning into no sweat, may lead to tachycardia, shock, etc.
- Non exertional heat exhaustion (classic heat stroke)
More commonly seen in elderly and frail individuals as well as patients with chronic diseases. The vast majority of patients have no sweating symptoms, dry red skin and fever, and the highest rectal temperature can reach 46.5 ℃. At the beginning of the illness, it may manifest as abnormal behavior or epileptic seizures, followed by confusion, delirium, coma, etc. Severe cases may present with symptoms such as hypotension, shock, arrhythmia, as well as heart failure, pulmonary edema, and cerebral edema.
complication
- Central nervous system dysfunction
Severe central nervous system damage can occur in the early stages of heat stroke, manifested as delirium, drowsiness, epileptic seizures, coma, etc; Other neurological abnormalities may also occur, including strange behavior, hallucinations, kyphosis, and cerebral rigidity.
- Coagulation dysfunction
Clinical manifestations include skin bruising, ecchymoses, bleeding at puncture sites, conjunctival hemorrhage, black stools, bloody stools, hemoptysis, hematuria, intracranial hemorrhage, etc. Approximately 45% of patients have disseminated intravascular coagulation (DIC), indicating poor prognosis.
- Liver injury
Severe liver injury is an important characteristic of exertional heat stroke, with the most common clinical manifestations being fatigue, poor appetite, and jaundice of the sclera.
- Renal injury
Patients with heat stroke often have kidney damage, manifested as oliguria, anuria, and dark urine color (strong tea or soy sauce urine). 25% to 35% of patients with exertional heat stroke and 5% of patients with classical heat stroke experience acute oliguria renal failure.
- Abnormal respiratory function
Early symptoms include shortness of breath and cyanosis of the lips, and approximately 10% of patients may develop acute respiratory distress syndrome (ARDS).
- Gastrointestinal dysfunction
Gastrointestinal dysfunction can occur within 72 hours of the onset of heat stroke, manifested as nausea, vomiting, abdominal pain, diarrhea, and watery stools. In severe cases, gastrointestinal bleeding, perforation, peritonitis, etc. may occur. Due to damage to the intestinal endothelium, the translocation of intestinal bacteria and toxins can induce or exacerbate systemic inflammatory responses, intestinal infections, and even shock in heat stroke.
- Myocardial injury
Myocardial injury can occur on the first day of onset, mainly manifested as tachycardia and hypotension, with a few patients presenting as sinus bradycardia.
- Rhabdomyolysis
Rhabdomyolysis is a serious complication of heat stroke, characterized by muscle soreness, stiffness, muscle weakness, brownish urine, soy sauce urine, and later muscle swelling and compartment syndrome, ultimately leading to acute kidney failure.