#Epi 105 - ICU Primary Snippet - Fever, Hyperthermia and Paracetamol

So today we are going to dive into the fever and hypothermia.

So can you please compare and contrast fever and hypothermia using the following headings? Physiological mechanisms, causes.

So fever and hypothermia.

They're both elevation of the core temperature of the body, but the underlying mechanism is different.

So for a fever, that's a normal part of the innate immune response.

So it's physiological, whereas hypothermia is elevation of the core temperature due to a failure of thermoregulatory responses to manage internal or external heat gain.

So with a fever, hypothalamus is like your body's thermometer or thermostat.

The hypothalamus controls the temperature what is meant to be a normal core body temperature.

So with a fever, that set point is increased and it inappropriately triggers body's heat generation and conservation mechanisms.

So you get shivering and vasoconstriction.

So the body thinks that this new set point is the normal core temperature for the body.

Whereas with hypothermia, the hypothalamic set point remains unaltered, but the body's cooling mechanisms such as basal dilatation and sweating are overwhelmed.

And the increased temperature that it results in causes increased oxygen consumption and metabolic rate.

So you'll see things like increased heart rate, respiratory rate, and then eventually a cytokine-mediated inflammatory response.

So you'll see people with severe hypothermia they can get multi-organ dysfunction.

And then that's also how people can die in these situations.

And we've seen it like recently, there's been that heat wave, speaking of Europe, in Europe, in Paris, where people have actually died because of hypothermia.

So From a cause perspective, from fever, it's often exogenous pyogenes.

So the things we usually think about is some sort of microbiome, usually things like bacteria.

So for example, if we think about gram-negative sepsis, so the gram-negative bacteria have lipopolysaccharide endotoxins.

which can trigger this fever response.

Or, for example, gram-positive organisms like Staph aureus have enteroexotoxins.

Or things like fungi can also stimulate the T cells and the MHC class 2.

So this also basically caused the hypothalamic set point to increase.

Non-infectious causes can also result in fever.