Hypo & Hyper thermia

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Hypo & Hyper Thermia

Dr. Mohammed Saleh Madadin

Forensic Medicine

College of Medicine – university of



Thermal Injuries

Exposure To cold

Exposure to

Heat

Generaleffects

Localeffects General

effectsLocaleffects



Definitions

Thermal Death

Internal Heat

Enviromental Heat

Heat Load ( gain)

Heat Loss

1 C = 33.8 F



Heat loss and Heat gain

Heat is gained:

by conduction from warm air surrounding the body

by the body’s metabolic activity ( liver & muscles)

Heat is lost:

by conduction and radiation to cold air (or water)

by evaporation of sweat from the body surface



Mechanism Of regulation of

body Temp.Whenever the heat load exceeds the heatloss body heat rise and body start loss heat

How body decrease temp:

1-vasodilation of bl.v due to inh. Of symp.centre in post.hypothalamus

2-sweating

3- decrease heat production ( inhibitchemical thermogenesis)



How body increase temp .?

1- V.C due to stim. Of post.hypothalamus

2- piloerection due to stim. Of sympathetic sys.

3- increase heat production by promoting shivering

Internal heat maintained despiteenviromental variations bythermoregulatory mech.



nerves

Less heat generated

More water covers theskin.

More evaporation

Skin arteries dilateMore blood to the

skin.More radiation &conduction of heat

Muscles of

skin arteriolewalls relaxSweatglands

increasesecretion

Musclesreduceactivity

Core bodytemperature

>37°C

Hypothalamus

Thermoreceptors



nerves

More heat

generated

Less water covers theskin.

Less evaporation

Skin arteriesconstrict

Less blood to theskin.

Less radiation &

conduction of heat

Muscles of

skin arteriolewallsconstrict

Sweatglands

decreasesecretion

Musclesshivering

nerves

Core bodytemperature

<37°C

Thermoreceptors

Hypothalamus



Hyperthermia

Systemic hyperthermia

Endogenous \ Febrile hyperthermia

Exogenous\ non-febrile hypothermiaHeat Cramps

Heat Exhaustion ( Heat prostration)

Heat Syncope ( Heat collapse)

Malignant hyperthermia



Heat Stroke

Increase in body temp. above 41C inpresence of environmental heat.

ability to cool the body can no longercompensate for the heat load

life-threatening conditionhot, dry skin, altered sensorium,tachycardia, hypotension ,

hyperventilation



Predisposing Factors:

alcoholism, dehydration, obesity,preexisting disease (cardiac and

neurological), diuretics and majortranquilizers such asphenothiazines,tricyclic antidepressants,and monoamine oxidase inhibitors ,sympathomimitic e.g cocain and amphet..Relative humidity , DM



Obese individuals show a greatersusceptibility to heat stroke ….. Why ?

This is due to :(1) Increased adipose tissue creates

an greater demand on the heart

(2) the fat provides extra insulationfor the body, preventing loss of heat

(3) since metabolic heat is produced

in proportion to the bulk of the tissue



Heat stroke is generally seen in twosettings

1- that involving relatively youngindividuals exposed to high

temperatures while undergoingextreme exertion — military recruitsand football players in training

2- a prolonged heat wave. In this lattercircumstance affected individuals are



also occur in children left unattendedin automobiles for long periods of timein the summer

Symptoms of heat stroke may come on

suddenly or be preceded by prodromicsymptoms — nausea, vomiting,vertigo, muscle cramps, dyspnea, afeeling of warmth.

increase in heart rate Paresthesias



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Complication:

If lives short time after acute insult :

PneumoniaTub. Necrosis of kidney

adrenal Hmg

hepatic necrosis

myocardial fiber necrosis &

subendocardia HMG



If the diagnosis of heat stroke has not

been made prior to death, thediagnosis is often circumstantial basedon history, exclusion of other causes of death

If an individual’s time of death is

known and if a rectal temperaturetaken shortly thereafter showshyperthermia, a diagnosis of heatstroke can be made



Cause of death in hyperthermia

Cardiac dyasarrythmia and collapse

seizures

Shock

Autopsy finding:not specific



Heat acclimatization

tolerance to exercise in heat

Due to Subsequent to repeated bouts

of exercise in a hot environment The 1ry benefit evident as a reductionof the incidence or severity of symptoms of heat illness, andincreased work output concurrent withreduced cardiovascular, thermal, andmetabolic strain.

in metabolic biochemical



Saunas

Exposure to hot & dry environment

60- 120 C

10 – 30 min.

Core Temp begin to rise 1-3 min. ,constant increase rate

Once outside temp back to normal (

30 min.)

Sweating the only way to cooling

Pt with severe heart dis. At risk




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Hypothermia

In the past, injury and death from theeffects of low temperature wasthought to occur almost exclusively

among those subjected to extremes of climate out of doors.

Now, generally appreciated that

hypothermia was a common andwidespread danger in temperateclimates and indoors.



Case

In Germany , December 2002 , mancalled a police , reporting he found hisdisabled GirlFriend lying dead on the

living room Floor.

She lives alone

DecemberDisabledLive alone



Either :

1- General2-Localized

Dry or in water

Considered hypothermia when templess 35C

External parts of body : enviromentalDependentInternal part : constant temp. ( core

Temp.)



Case

In December 2002 , man called apolice , reporting he found his disabledGirlFriend lying dead on the living

room Floor.

She lives alone , last time seen last 2days

Crime scene Inv.:

The floor was flooded with water

The ambient temp. was 19C



Loss of heat in water faster than in air

The aged and the infants are mostvulnerable

Very high mortality of hypothermia in firstfew weeks of life ( relation of surface areato mass and heat regulation centreimmature)



Pathophysiology of hypothermia

Internal temp. regulated by

- Heat production :metabolism , muscular activity

- Heat loss :

increasing blood flow through skin or

sweating



Brown fat play role in chemicalthermogenesis by increase rate of metabolism

in children heat production up to 100%while in adult no brown fat ( 10-15%heat production)



Circumstances of hypothermia :

- exogenous : environmental (less 10C)

- Endogenous : dis. Of endocrine glands ,drugs (barb. , diazepam) , mental dis.

- Other :

Age and physiqueSocial and financial factors



LOW ENVIRONMENTALTEMPERATURE:

Critical temp. of air to maintain eqili.

25 CNo specific figure , depend on otherfactors

10 C consider to be danger to causehypothermia

External winds will worse the effect



HYPOTHYROIDISM

Myxoedema , women , over 70

DrugsImipramine , chlorpromazine ,diazepam , barb.,alcohol

clothing

Women tolerate cold better due tothick layer of s.c fat



Alcohol tend to aggravate the loweringof body temp rather than rising ( theheat generated by alcohol is due

internal combustion which thereforelowers the temperature of inner core of the body)

Cutaneous diltation of peripheralvessels (loss of heat and warm flush

feeling)



Alcohol have a secondary effectcausing incapacity and immobility.



Mechanism of death

As temp. falls decrease indissociation of oxyheamoglobin lesssupply of O2 to tissue (most affected

nervous tissue)

utilizing capacity of tissue is reducedat lower temp., all these depress the

oxidative process in the tissue andleading to tissue hypoxia

Therefore the immediate cause of

death is circulatory failure



Clinical Manifestation

36°C -32°C: feeling of being cold,shivering and constriction of bloodvessels

32°C -24C :dulling of consciousness, afall in respiration and heart rate, and alowering of blood pressure

Loss of reflexes , cold necrosis ,



Hypothermia can causeheamoconcentration by:

1- cold diuresis (15C) trigger diuresis

2-leaking of plasma into ECF ( coldedema)

Hyperglycemia :caused by action of glucocorticoid , and epinephrine on liver

which resultant depletion of glycogen.

Case



CaseIn December 2002 , man called a police , reporting he foundhis disabled GirlFriend lying dead on the living room Floor.

She lives alone , last time seen last 2 days

Crime scene Inv.:


The ambient temp. was 19CWomen rectal temp. was 16 C

The tap water temp was 16 CAutopsy :Rigor fully developedHypostasis pinkFrost erythema on her kneesMultiple erosion spots on

gastric mucosa



Autopsy

There may be no signs at autopsy

history may be all-important

If pt admitted to hospital and 'warmed-up', death may supervene at any timeup to a few days later.

signs of hypothermia: patches of pinkto brownish pink discoloration may beseen

The color of hypostasis cherry red or





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extremities may be cyanosed or theymay be white

Sometimes the feet are blue to theankles, above which is pale.

Oedema may be seen

blistering of the skinSigns of pre-existing disease



Lesions with hypothermia

ACUTE GASTRICEROSIONS(Wischnevsky’s Gastriclesion):

The stomach mucosa have numerousshallow ulcers, the floor of eachcontaining a dark brown plug of alteredblood

the stomach contents sometimescontain dark acid-affected blood.





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PULMONARY OEDEMA: common butnot specific

PENVASCULAR HAEMORRHAGES:

in the brain, especially in the walls of the third ventricle, they are notparticularly specific

Microinfarcts are common in manyorgans in hypothermia.

Case



CaseIn December 2002 , man called a police , reporting he found his disabledGirlFriend lying dead on the living room Floor.

She lives alone , last time seen last 2 daysCrime scene Inv.:


The ambient temp. was 19C

Women rectal temp. was 16 C

The tap water temp was 16 C

Autopsy :Rigor fully developedHypostasis pinkFrost erythema on her kneesMultiple erosion spots on gastric mucosa

Toxicology And Histology

toxicology : -veHistology : Wischnevsky’s spots

Diagnosis Made as Fatal



THE 'HIDE-AND-DIE'SYNDROMEAlso called terminal burrowingbehavior

In some cases of hypothermic death inthat it is associated with the victimundressing and hiding away from sight

The signs of hypothermia are usuallypresent

problem then arises as to whether thevictim became hypothermic first,which led to mental confusion that



Paradoxical undressing

Perimortem act in wich the victimremoves his clothing

Due to

- Terminal hallucination

- Physiologically when failure of V.C

lead to warm blood flow back to theskin lead to burning sensation



Biochemical markers of hypothermia

catecholamines appear in the bloodand then urine in the early stages, butthen decline, as the adrenals becomeexhausted.

- There is a variation in theadrenaline:noradrenaline ratio, allthese changes being manifestations of

stress induced by low temperature



Hypothermia in Water

70-90 min. to die if immersed in water4-9C and in 30 min at 0 C

Critical temp. of water to maintaineqili. 35 C

Thickness of individual S.C fat is mostimp. Factor



Cause of Death

Sudden cooling of the skin const. of bl.v reflex stim. Of heart incr. blpressure and C.O Sudden increase inwork of Lt vent Vent. fibrillation (bothatrial and vent. Ectopic beat common

during 1st few min. of cold imerssion)reflex disturbance of breathing:involuntary Controlled breathig lead to

inhl. Of water



Post immersion Death

Occur following rescue from cold water

Conc. When taken out

Because of continuous drop of temp.for period of time even if rewarmed

Cause of death : cardiac arrest



LOCAL INJURY DUE TO COLD

There are a number of different clinicallesions caused by the effect of

prolonged cold on the extremities.

1- 'Immersion foot' and 'trench foot'

refer to damp cold damage lead tonecrosis and gangren

- ' '




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Case # 2

In Japan , a morning in January, amale in his early sixties was founddead in an outdoor parking area.

The minimum temperature during thenight before he was found dead wasestimated to be 4.0°C.

Autopsy revealed the pinkness of hypostasis, slight abrasions andbruises on the face and the

extremities, collapse of the lungs, and



Expalanation

Hyperacetonemia : occurin hypothermia

Ubiquitin: one of the

Hypo & Hyper thermia

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