2/13/2014 Lori Weichenthal, MD, FACEP Associate Professor of - - PDF document

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Lori Weichenthal, MD, FACEP Associate Professor of Clinical Emergency Medicine UCSF Fresno

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INTRODUCTION

• Th

Thermoregulat lation

• n
• Acclimatization

Acclimatization

• Field Managem

Field Management nt of Heat Illness

• f Heat Illness
• Solar Injur

Solar Injury

• Questions and Conclusion

Questions and Conclusion THERMOREGULATION

• The

The body regulat body regulates t s temperature lik erature like a a furnace furnace

• The h

The hypo pothalamus is the thermostat thalamus is the thermostat

• It responds

It responds to v variou rious recept receptors s

• Adjust t

just to keep eep core t core temperature betw erature between 36.5 een 36.5 and 3 and 37.5 .5 degrees degrees Celsius Celsius

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THERMOREGULATION

• Reactions at a

actions at a cellular le cellular level are l are mainly e mainly exothermi rmic

• At rest,

rest, a a human generat human generates es about 1 about 100 kcal/hr 00 kcal/hr.

• Moderat

Moderate activity adds activity adds an an additional 300-600 kcal/hr additional 300-600 kcal/hr.

• Solar radiation adds

Solar radiation adds 150 50 kcal/hr kcal/hr.

• Heat can be lost

Heat can be lost and gained fr and gained from

• m

the body b the body by:

• Ev

Evaporation aporation

• Radiation

Radiation

• Conduction

Conduction

• Con

Convection ection

THERMOREGULATION

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EVAPORATION

• Most ef

Most efficient cooling mechanism cient cooling mechanism

• Respirat

spirator

• ry loss and

y loss and sw sweat eat

• Acco

counts f unts for 30 % of heat dissipation at r 30 % of heat dissipation at average e erage external t rnal temperatures eratures

• Major cooling mechanism at

Major cooling mechanism at temperatures eratures great greater that 35 degrees Celsius r that 35 degrees Celsius

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RADIATION

• Transf

ansfer of heat betw er of heat between the body and een the body and the the en envir vironment via electr nment via electromagnetic w

• magnetic waves
• Ov

Over 50 % of cooling when ambient er 50 % of cooling when ambient temperature is erature is less than body t less than body temperature erature

• Wh

Why y it is im it is impor portant ant to co cover up when it is cold r up when it is cold

CONDUCTION

• Transf

ansfer of heat betw er of heat between tw een two objects that are

• objects that are

in direct in direct contact contact

• Heat loss is

Heat loss is minimal e minimal except with: cept with:

• Water immersio

r immersion

• Lying on cold gr

ing on cold ground

• und

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CONVECTION

• Heat transf

Heat transfer betw er between the body and een the body and a a mo moving ving gas or liq gas or liquid id

• Rat

Rate of heat transf

• f heat transfer is

er is dependent on: dependent on:

• Speed of air

Speed of air or w

• r water
• Temperature of each substance

erature of each substance

• In still air

In still air, 25 25 % of heat % of heat loss is loss is via con via convection tion

• As wind speeds up, becomes

As wind speeds up, becomes great greater

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HEAT ACCLIMATIZATION

• Re

Requ quires u up to to 1 14 d days

• Ear

Early

• Reduced heart rate
• Expanded plasma volume
• Autonomic nervous system habituation
• Lat

Late

• Increased sweat rate/production
• Conservation of sodium

HEAT ILLNESS

• Ph

Physiologi ysiologic R c Response sponse

• Pat

Pathoph

• physiology

siology

• Presentation

Presentation

• Management

Management

• Pre

Prevention ention

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PHYSIOLOGIC RESPONSE TO HEAT

• Hypo

pothalamus at thalamus attempts t ts to maintain id maintain ideal eal bod body te temp mperature

• Shun

Shunts bloo ts blood

• Vasodilation, es

dilation, especially o cially of s skin

• Splanchnic v

lanchnic vasoconstriction constriction

• Increases ca

Increases cardia iac out c output ut

• Increased cat

Increased catecholam cholamines ines activ activate sw sweat glan eat glands ds

• Ad

Adaptive ve r responses

PATHOPHYSIOLOGY OF HEAT ILLNESS

• Ph

Physiologi ysiologic response de c response deteriorat riorates as es as car cardiac iac

• utpu
• utput

and and vasodilatatio sodilatation reach their limits reach their limits

• Electr

Electrolyt

• lyte losses and

e losses and deh dehydration contribut dration contribute to pr progr

• gression

ssion

• Serious heat illness o

Serious heat illness occur ccurs when when normal body normal body temperature can erature can no not be t be maintained maintained

• Is a spectrum

Is a spectrum

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• Elderly

Elderly

• Neonat

Neonates es

• Obesity

Obesity

• Alco

Alcoho holis lism

• Deh

Dehydratio dration

• Hyper

Hyperthyroidism idism

• Medicatio

Medications

• Drugs of abuse

Drugs of abuse

• Socioeconomic

Socioeconomic

• Conf

Confinement inement

• Extre

Extreme activ e activities ties

RISK FACTORS FOR HEAT ILLNESS TYPES OF HEAT ILLNESS

• Heat edema

Heat edema

• Heat rash

Heat rash

• Heat cram

Heat cramps ps

• Heat synco

Heat syncope

• Heat e

Heat exhaus haustio tion

• Heat str

Heat stroke

Mild to severe

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CASE SCENARIO You u are ser are serving ing as a medical as a medical volunt lunteer eer for the Badw r the Badwat ater Ultra maratho er Ultra marathon at at an an aid aid station at station at St Stovepipe W epipe Wells, at lls, at the 42 mile point f the 42 mile point for the race, when a r the race, when a bystander appr stander approaches y

• aches you concerned

u concerned that she that she has increased lo has increased lower r extremity edema since arriving t tremity edema since arriving to Deat ath V Valley f y from Ont

• m Ontario, Canada
• , Canada .

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HEAT EDEMA-PRESENTATION

• Sw

Swelling of e elling of extremities associat tremities associated with high ed with high temperatures eratures

• Occurs during heat w

Occurs during heat waves or when a s or when a per person

• n

fr from a

• m a cool climat

cool climate tra e travels t els to a a warm one rm one

• Body retains w

Body retains water and r and has tr has trouble e

• uble excre

creting ing salt salt

• Due t

Due to an an increase in increase in aldost aldoster erone

• ne

HEAT EDEMA-TREATMENT

• Mo

Move t to a a cool space cool space

• Pr

Provide cool fluids ide cool fluids

• Ele

Elevat ate sw e swollen e

• llen extremities

tremities

• Allo

Allow time f w time for acclimatization r acclimatization

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CASE SCENARIO

Still at Still at your post at ur post at St Stovepipe W epipe Wells, a lls, a staf staff f memb member f er for the race a r the race appr pproaches

• aches y

you with the u with the com complaint of a laint of a red red itch itchy rash. y rash. She is She is extremely tremely uncomf uncomfor

• rtable

table and and is asking y is asking you what u what to do. do.

HEAT RASH-PRESENTATION

• Also kno

Also know as prickly heat or milaria as prickly heat or milaria

• De

Develops when sw lops when sweat du eat ducts beco cts become me blo blocked

• Presentation ranges fr

Presentation ranges from

• m super

superficial blist ial blisters to deep, deep, red bum red bumps

• Usually in

Usually in folds of skin or where clo lds of skin or where clothing hing causes friction with skin causes friction with skin

• Symp

mptoms ms r range f from a

• m asymptoma
• matic r

ic rash t to se severe itch re itchy/prick y/prickly rash y rash

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HEAT RASH-MANAGEMENT

• Usually g

goes aw away ay o

• n its o
• wn
• Keeping skin

eeping skin cool cool and pre and preventing enting sw sweat eat is is helpfu helpful

• Dress in

Dress in loose, lightw loose, lightweight clo eight clothing hing

• Sta

Stay in in air air conditioning conditioning

• Af

After bathing, let y r bathing, let your skin ur skin air air dr dry

• Use calamine lo

Use calamine lotio tion or coo

• r cool com

compresses

• In

In se severe cases, st re cases, ster eroids ma

• ids may be

y be req require ired

CASE SCENARIO

As As the runner the runners star s start t t to reach y reach your aid ur aid station, a station, a 45 y 45 year old male par ar old male participant presents with icipant presents with se severe right calf cra re right calf cramping that ping that mak makes him him unable t unable to w walk or run. lk or run.

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HEAT CRAMPS-PRESENTATION

• Pain

Painful mu ful muscle s le spasms d asms due t to sustai sustaine ned sk d skel eletal al musc muscle contrac contractions

• ns
• Of

Often unilat n unilateral and in eral and involving calf lving calf muscles muscles

• Caused by

by r relative ve hy hyponatremia d due to to replacement of replacement of water losses with r losses with hypo potonic solutions

• nic solutions

HEAT CRAMPS-MANAGEMENT

• Rest and

st and cool do cool down wn

• Oral salt reh

Oral salt rehydration with electr dration with electrolyt yte e containing spor containing sport drink or salt solution t drink or salt solution

• Gentle range

Gentle range of mo

• f motion and

tion and massage massage

• Avoid strenuous activity f
• id strenuous activity for se

r several hours ral hours

• In

In se severe cases, IV h re cases, IV hydration ma dration may be req y be required ired

• Ma

May be able t y be able to re retu turn rn to e event ent

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CASE SCENARIO

A A 25 y 25 year old ar old female par male participant st icipant stops at

• ps at your

ur aid aid station f station for w r water and r and pr prom

• mptly passes out.

ptly passes out. One of the w One of the water att r attendants catches her and endants catches her and lo lowers her t rs her to the gr the ground.

• und. She pr

She prom

• mptly

ptly regains consciousness and regains consciousness and wants t nts to return t return to the race. the race.

HEAT SYNCOPE-PRESENTATION

• Syncop

Syncope due t e due to or

• rtho

thostatic h tatic hypo potension nsion

• Of

Often not pr n not prof

• foundly deh
• undly dehydrat

drated or ed or hy hyperthermic

• Usually in

ually in the p the poorly acclimatized o

• rly acclimatized or

elderl elderly

• Of

Often occur n occurs when per when person is standing/

• n is standing/

stationar stationary

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HEAT SYNCOPE-TREATMENT

• Place patient in

Place patient in supine position supine position

• Ele

Elevat ate the f e the feet et

• Re

Remove ve f from d direct s sunlight

• Oral reh

Oral rehydration dration

• Should no

Should not return t t return to the e the event ent

• Need fur

Need further her medical e medical evaluation aluation

CASE SCENARIO

A A 63 y 63 year old ar old male runner appr male runner approaches y

• aches your aid

ur aid station but collapses prio station but collapses prior t r to reaching it. reaching it. When When he is carried he is carried int into y your t ur tent he is sw ent he is sweating eating pr profusely

• fusely, v

vomiting, and miting, and com complaining of laining of headache.

• headache. He is

He is awak ake and e and aler

• alert. When y
• t. When you

u measure his measure his temperature it erature it is is 39.4 39.4 C C (1 (103 F). 03 F).

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HEAT EXHAUSTION-PRESENTATION

• Symp

mptoms ms i include:

• Nausea, v

Nausea, vomiting miting

• Fatigue, w

tigue, weakness, dizziness akness, dizziness

• Headache, muscle cram

Headache, muscle cramps ps

• Patients are usually sw

Patients are usually sweating eating

• Temperature is

erature is typically < 40 C (1 typically < 40 C (104 F) 04 F)

• Mental status is normal

Mental status is normal

HEAT EXHAUSTION-MANAGEMENT

• Mo

Move t to cool, shaded area cool, shaded area

• Remo

move constrictiv constrictive clo clothing hing

• Oral reh

Oral rehydration or IV dration or IV fluids fluids

• Apply activ

Apply active cooling measures cooling measures

• If patient stabilizes, transf

If patient stabilizes, transfer f er for medical r medical att attention ention

• If no

If no im impr provement, e ement, evacuat acuate immediat immediately ely

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CASE SCENARIO A 42 y A 42 year old w ar old woman is transpor man is transported t d to your aid ur aid station af station after ha r having a ving a witnessed witnessed seizure.

• seizure. She is

She is obtunded, tach

• btunded, tachycar

ardic, dic, ho hot and dr t and dry t y to t touch.

• uch. Her t

Her temperature is erature is 40.5 40.5 C (1 C (105 05 F). F).

HEAT STROKE-PRESENTATION

• Sym

Symptoms similar t ms similar to heat e heat exhaustion haustion

• Patien

Patients freq ts freque uently lose the ability t ntly lose the ability to sw sweat eat

• Temperatur

ure is > 40 is > 40 C (1 C (104 04 F) F)

• Patien

tients do no ts do not ha t have a a norma normal menta l mental status status

• Organ syst

Organ system failure occur em failure occurs

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HEAT STROKE-MANAGEMENT

• Address the ABCs

ddress the ABCs

• Plan f

Plan for r immediat immediate e evacuation acuation

• Remo

move as as mu much clo ch clothing as ng as possible possible

• Perform ac
• rm active c

cooling m

• ling measures

asures

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HEAT ILLNESS-PREVENTION

• Allo

Allow w for acclimatization r acclimatization

• 7-1

7-10 da days f ys for adults r adults

• 10-1
• 14 da

4 days f ys for children and r children and the elderly the elderly

• Monit

Monitor w r weather conditions ather conditions

• Good h

Good hydration dration

• Goal of clear urine

Goal of clear urine

• Wear

ar light w light weight, light colored clo ight, light colored clothing hing

SOLAR INJURY

• Pr

Prol

• long
• nged sun e

ed sun exposure can cause skin posure can cause skin and e and eye damage e damage

• People with light skin, hair and e
• ple with light skin, hair and eyes are

es are more at more at risk risk

• Cer

Certain medications increase risk ain medications increase risk

• Re

Remember t the f five ve S S’s

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MEDIC MEDICATI TIONS ASSOCI ONS ASSOCIATED WITH SUN SENSI WITH SUN SENSITIVI IVITY

NS NSAIDs AIDs ibup uprofen, napr naproxen en, ketoprofen en, celeco celecoxib, b, pir piroxicam cam Antib Antibiotics tetracyclines, f lines, fluoroquinol quinolone

• nes

(ciproflo floxacin, o , ofloxaci cin), n), sul sulfon

• nam

amides Stat Statins at ator

• rva

vast stati atin, fl fluvastati tin, lo lovastatin, pra , pravastatin, sim simvas astatin Hypogly Hypoglycem emics ics sul sulfon

• nylurea

eas (gli (glipizide, , gl glyburi yburide) Diur uretics etics furos

• semid

ide, h hydroclorothi thiazi zide Sun Sunscreen eens para-amino minobe benzoic nzoic a acid ( (PABA), cinna nnamates, be s, benzophe henone nones, s, sa sali licyla lates Fragran agrances ces musk ambre musk ambrette, , 6- 6- me meth thylcou ylcoumari arin, sandalw sandalwood

THE FIVE S’S

• Slip o
• n p

prot

• tectiv

ective clothing clothing

• Slop on sunsc

Slop on sunscreen een

• Slap on a

Slap on a br broad-brimmed

• ad-brimmed hat

hat

• Seek

Seek shade shade

• Slide on sung

Slide on sunglasse sses

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