New Delhi: As India continues to reel under extremely high temperatures, the reports of people dropping dead due to severe heat conditions have been hitting headlines.
The statistics by the National Centre for Disease Control (NCDC) under the Union health ministry, accessed by ThePrint, show that 40,211 heat stroke cases and 110 deaths due to conditions have been registered between 1 March and 18 June. Most of these fatalities, 52, were recorded in June.
Ministry officials, however, concede that the actual figures could be way higher as many states are not updating data regularly. They also admit that while the NCDC has been capturing this data for the last few years, the magnitude this year appears much higher.
ThePrint explains what exactly leads to a human body giving in to extremely high temperatures and why every fever during the heatwave conditions should be keenly monitored.
The stress heat puts on human body
The typical body temperature hovers around 37ºC (36.1–37.8ºC/ 96.98—100.04ºF), regulated by the thermo regulatory centre in the hypothalamus of the brain. It maintains equilibrium between internal heat production and external heat exchange, primarily through sweat evaporation and some other methods include convection, respiration, and conduction.
Dr Neeraj Nischal, additional professor in Department of Medicine at AIIMS- Delhi, explained that as external temperatures approach or surpass skin temperature, heat loss through convection diminishes, leaving sweat evaporation as the sole avenue, influenced by humidity levels.
Extreme temperatures and humidity impede efficient heat dissipation, while physical exertion generates internal heat, which, when coupled with environmental factors, can quickly lead to heat accumulation.
If heat gain exceeds loss, the body temperature rises, triggering the hypothalamic regulatory system to prompt responses like sweating, peripheral vasodilation, and increased cardiac activity, redistributing blood from the body core to the skin to lower temperature.
Prolonged exposure to high temperatures and excessive sweating can deplete salt and water levels. Inadequate replenishment of fluids and electrolytes leads to dehydration and hyponatremia, resulting in heat cramps and potentially progressing to heat exhaustion if left untreated.
Failure of the thermoregulatory mechanism further raises core body temperature. The concept of a “thermal maximum” was devised to gauge the intensity and duration of heat exposure that cells can endure before sustaining damage, Nischal said.
For humans, the thermal maximum is typically recognised as a core body temperature of around 42°C (107.6°F) lasting between 45 minutes and eight hours.
Elevated body temperatures exceeding 40.5°C (104.9°C) can cause harm to cellular structures, triggering the release of inflammatory factors and increasing gastrointestinal permeability, potentially allowing endotoxins to enter the bloodstream. This can lead to multi-organ failure (including kidney and liver), acute respiratory distress syndrome, and disseminated intravascular coagulation.
Body temperatures surpassing 41.1°C (106°F), on the other hand, are linked to neurological dysfunction.
“The heightened cardiovascular strain induced by heat, characterised by vasodilation and dehydration, can exacerbate existing health conditions such as cardiovascular disease. Intrinsic factors like chronic dehydration, limited cardiovascular capacity, and lack of acclimatisation can hinder the body’s response to heat stress,” Nischal said.
Additionally, certain medications such as beta blockers, vasoconstrictors, and sedatives can disrupt thermoregulatory responses.
Heat-related illnesses also occur when the body’s ability to regulate temperature is overwhelmed, particularly in chronically ill individuals or those at extreme ages where cardiovascular function may be compromised.
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How heat can kill
Heat-related illness represents a spectrum of conditions stemming from the body’s struggle to regulate heat. This encompasses minor ailments like heat edema, heat rash, cramps, tetany, syncope (fainting), and exhaustion, with heat stroke being the most severe manifestation.
Heat exposure can exacerbate respiratory, cardiovascular, electrolyte, and renal issues, leading to mild to fatal outcomes. Heat cramps, the mildest form, result from dehydration and sodium depletion, often during intense physical activity, characterised by elevated body temperature and painful muscle spasms.
Heat exhaustion, a moderate form of heat illness, on the other hand, involves elevated core temperature but preserved central nervous system (CNS) function, presenting symptoms such as nausea, weakness, and confusion.
But without intervention, it can progress to heatstroke, marked by hyperthermia, CNS impairment, and potentially life-threatening complications affecting multiple organs.
Specialists stress that classic and exertional heat stroke represent distinct categories, affecting sedentary individuals and those engaged in strenuous activity, respectively, with both posing high risks of morbidity and mortality if cooling therapy is delayed.
The symptoms of heat exhaustion typically include extreme weakness, lightheadedness, syncope, profuse sweating, muscle cramps, headache, difficulty continuing physical activity, and core body temperature of 101-104°F (38.3°C-40°C).
However, absence of significant CNS dysfunction such as seizures or altered consciousness, distinguishes it from heat stroke and the preventive measures include maintaining hydration by drinking fluids 4-6 hours before physical training, avoiding exercising in severe heat or humidity.
Warning signs of heat stroke, on the other hand, include headache, dizziness, nausea, confusion or disorientation, loss of consciousness, seizures, and hot, red, dry, or moist skin with a temperature exceeding 105°F (40.6°C).
These symptoms are particularly significant following prolonged exposure to the sun or outdoor activities, compounded by factors such as dehydration and pre-existing medical conditions like hypertension.
Dr Tushar Tayal, consultant with the department of internal medicine at C.K. Birla Hospital in Gurugram, explained that heat-stroke occurs when the body is unable to regulate its temperature due to prolonged exposure to high temperatures.
Normally, the body regulates its temperature through sweating and increasing blood flow to the skin. But in heat stroke, these mechanisms fail, causing body temperature to rise uncontrollably, often exceeding 104°F (40°C).
“Also, there is cell damage leading to the breakdown of proteins and cell membranes which can lead to multiple organ failure. Heat stroke can also affect the blood pressure causing it to drop significantly again leading to organ failure. It can also disrupt the blood’s ability to clot, leading to widespread bleeding. Finally there is widespread inflammation leading to sepsis-like conditions — all of which may lead to death of the patient,” Tayal said.
Experts, however, maintain that while those particularly vulnerable include kids and elderly, manual labourers and people with comorbidities, most deaths can be prevented if the symptoms are identified quickly and medical management is initiated.
Though not very common, there is another flipside of people suffering heat exhaustion and heat stroke. Even those who survive the extreme heat-related complications sometimes end up with severe disabilities such as stroke which results in permanent disability.
“Also, in people with underlying health conditions such as kidney disease, severe heat-related illness may trigger a permanent damage to the organ, forcing them to go on dialysis,” Nischal said.
(Edited by Tony Rai)
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