Hyperthermia

What are the 5 methods of heat loss?

behavior control (you feel hot and decide to take a break/go inside, etc.)

sweating (increased cholinergic stimulation)

vasodilation (decreased sympathetic tone)

conduction of heat

convection of heat

What is the hemodynamic response when your body is hot?

hot makes you vasodilate to try to cool down

this causes stroke volume to diminish and to maintain cardiac output, the heart rate increases

• older pts or pts on certain meds may have a diminished tachycardic response so the output falls and may result in myocardial ischemia

water loss estimation and at what temp you start to swaet

sweating begins as body temp rises above 37C (38.5C for elderly)

every pound of water weight lost is equiv to 500mL of water (that’s what is needed to repace each pound)

What are some of the medications that interfere with heat removal? (6)

anticholinergic agents, diuretics, phenothiazines, beta bockers and calcium channel blockers, sympathomimetic agents like meth and cocaine, and alcohol (ethanol)

with acclimation, there is _____ sweating and ______ aldostereone which results in ____

increased sweating, increased aldosterone and sodium concentration results in more efficient sweating

explain heat edema

we have cutaneous vasodilation and this leads to venous pooling (seen in feet and ankles mostly)

treat by elevation

Explain the prickly heat/heat rash

you get inflammation over clothed areas of blocked sweat glands

treat with loose clothing, antihistamines, topical calamine, etc.

explain heat cramps and what they are thought to be due to

painful involuntary contractions during or shortly after physical exertion in the heat

thought to be due to fluid and electrolyte distrubances (esp. sodium)

treat: cool the patient, replace fluids and electrolytes, and slowly stretch muscles

What is this?

body temp is normal or slightly elevated (<40C) and mental status is normal

can see: HA, malaise, N/V, orthostatic changes, dehydration, etc.

swaeting remains intact

heat stress/ heat exhaustion

How do we treat heat stress/exhaustion?

elevate the legs, move to shady area f outside, replace water and leectrolytes orally or IV

can be treated outside of the hospital

What is this?

body temp >40C with altered mental status

often no sweating

multisystem organ failure

vacular permeability activates the coagulation cascade which leads to DIC

heat stroke

Classic heat stroke examples

elderly or very young

volume and electrolyte disturbances common

affects those with physiologic, psychologic, or pharmacologic impairment more (ex: raynaud’s)

What are teh two classic examples of confinement hyperpyrexia

children left in cars and stowaways

What are some CNS effects we see with heat stroke?

irritability, confusion, hallucinations, bizarre behavior, abnormal plantar repsonses (toes go up), decorticate or decerebrate positions, hemiplegia, coma

seizures are common

What are some organ dysfunctions we see with heat stroke? (7)

hypotension, electrolyte distrubnces (usually hyperkalemia), renal failure (rhabdo common- tea colored urine), heart failure, liver failure, acute respiratory distress syndrome, and DIC

What are some labs we should get? (don’t memorize, just be familiar)

glucose, cbc, complete metabolic panel, ABG, creatine phosphokinase, and ECG

with a heat stroke what do we see on ABG?

metabolic acidosis and respiratory alkalosis (breathing more to compensate)

What is the prefered method to cool someone down (we have a lot of options but this is prefered)

spray and fan them (evaporative method)

cheap, easy, and readily available

note that you don’t want to cause shivering bc that will raise body tem so sometimes need to use a benzo to stop that from happening

What is the goal with cooling methods? (what temp?)

cool the core oto normothermia (37C)

explain the role of antipyretics like acetaminophen and ibuprophen on treating heat-related illness

they have no role (not effective, don’t do anything)

heat stroke pts go ____ and heat stress/edema/cramp pts go ____

stroke go to ICU

all others can be discharged (as long as they are healthy)