heat exhaustion / stroke presented by –capt manish khandare rmo, 1stc chairperson – lt col p v...
Post on 29-Dec-2015
219 Views
Preview:
TRANSCRIPT
HEAT EXHAUSTION / STROKE
Presented by –Capt Manish Khandare RMO , 1STC
Chairperson – Lt Col P V Padman Cl spl (Med)
HIGH TEMP. + HIGH HUMIDITY + PHYSICAL WORK = HEAT ILLNESS.
When the body is unable to cool itself through sweating , serious heat illness may occur.
The most severe heat induced illnesses are heat exhaustion and heat stroke . If left untreated heat exhaustion could progress to heat stroke and possible death.
Normally the body temperature undergoes a regular circadian fluctuation of about 0.6*C being lowest in the morning and highest in the evening.
Body temperature is controlled by the hypothalamus.
Preoptic anterior and posterior hypothalamus receives two kinds of signals
1 – from peripheral nerves – reflects warmth / cold receptors.2 -- from the temperature of the blood bathing the regions.
Thermoregulatory center of the hypothalamus integrates these signals to maintain normal temperature.
A normal body temperature is ordinarily maintained , despite environmental variations , because the hypothalamic thermoregulatory center balances the excess heat production derived from metabolic activity in muscle and the liver with heat dissipation from the skin and the lungs.
The mean oral temperature is 36.8*+/-0.4*C ( 98.2*+/-0.7*F).
Heat disordersCirculatory instability
Heat syncope Heat edema
Heat induced skin disorders
Prickly heat (milaria rubra)
Water and electrolyte imbalance
Heat cramps Water depletion heat exhaustion Salt depletion heat exhaustion
Hyperthermic failure of thermoregulation
Heat stroke
Heat syncope
Orthostatic dizziness and fatigue Precipitated by prolonged standing Maybe a prelude to more serious heat effects due to
peripheral vascular pooling Collapse of venomotor tone
Heat oedema
Unacclimatized people in tropics due to cutaneous vasodilatation Venous stasis Expansion of ECF space
HEAT CRAMPS:
MUSCLE SPASMS USUALLY 1 TO 3 minsMAY RECUR UPTO SEVERAL HOURSDUE TO : MILD WATER INTOXICATION SALT DEPLETION
PRICKLY HEAT:PRICKLY HEAT:
ACUTE OR CHRONIC BLOCKAGE OF SWEAT DUCTS DUE TO ACUTE OR CHRONIC BLOCKAGE OF SWEAT DUCTS DUE TO MACERATION OF STRATUM CORNEUM.MACERATION OF STRATUM CORNEUM.
Manifests as erythematous , pruritic ,maculopapular rash.Manifests as erythematous , pruritic ,maculopapular rash.
Core temperature is less than 40*C (104*F)
No evidence of CNS dysfunction though some patients may be anxious or irritable.
HEAT EXHAUSTIONCLINICAL FEATURESincreased thirstweaknessfatiguefrontal headacheimpaired judgmentvertigonausea, vomitingmuscle crampsincreased core temp upto 40 degrees C (104 degree F )
Move patient to a cold room.
Remove clothes.
Cold sponging with cold water
Replacement of fluids and electrolytes.
HEAT STROKE
Triad of - hyperpyrexia (core body temperature >41.1*C /106*F )
- CNS dysfunction (delirium, convulsions or
coma)
- Hot dry skin
Heat stroke
Classic heat stroke: exposure to high
environmental temp in sedentary persons.
Exertional heat stroke: from strenuous physical
exercise in hot climate in healthy persons.
Non exertional heat stroke: Alcohol ,
MAOIs,amphetamines and by illicit use of
phencyclidine , lysergic acid diethylamide
(LSD).
Pathogenesis
Heat stroke: a syndrome of
multi organ dysfunction in which
encephalopathy is a dominant
feature.
Pathogenesis (contd)
Multi organ dysfunction is due to:
direct cytotoxic effects of heat
Inflammatory response of host
Direct cytotoxic effects of heat
Direct tissue injury: body temp 41.6-42oC (105*F-107*F) for 45 min to 8 hours
Attenuated heat shock response: decreased production of heat shock proteins (stress proteins)
PATHOGENESIS – HEAT STROKEHeatHeat
GIT(Gut ischaemia)Leakage of EndotoxinsMonocytes
Acute phaseresponse
TNF AlphaI L-1, 6, 10Endothelial cell activation
-- Interferes with thermoregulation-- Activation of coagulation-- Alters vascular-tone
Multi organfailure
Clinical manifestations
Hyperthermia and CNS dysfunction are the essential criteria for diagnosis
Hyperthermia: core temp -41*C (106*F)Hot dry man: absence of sweating
CNS dysfunction:Inappropriate behaviour, confusion, impaired
cognition, psychosis or coma
Clinical manifestationsTemperature – 106*F
Pulse – approx 130 beats /min is common
Blood pressure – usually hypotensive.
CNS – delirium , confusions ,delusions ,convulsions , coma.
Eye – may reveal nystagmus , pupils may be pinpoint or normal.
Clinical manifestations… GIT manifestations:
Diarrhoea, vomiting, GI hemorrhage, hepatic injury
Myocardial injury:Nonspecific ST-T changes on ECGElevated CK-MB enzyme
Renal – Acute Renal Failure is a common complication
37*C ( 98.6*F) – Normal body temperature.
38*C (100.4*F) – Sweating , feeling uncomfortable .
39*C (102.2*F) – Severe sweating , tachycardia and breathlessness.
40*C (104*F) – Fainting , dehydration , weakness , vomiting , headache ,dizziness , confusion , hallucination , delirium and drowsiness.
41*C (105.8*F) – condition worsens , palpitations may occur.
42*C (107.6*F) – May be comatosed , severe delirium , convulsions , tachycardia.
1. Complete blood count – elevated levels of WBCs as high as 40,000 /cu mm have been reported.
2. Serum electrolytes– hypokalaemia , hypocalcaemia and hypophosphataemia.
3. Blood sugar estimation – hypoglycemia usually seen.
4. Renal function tests – Elevation in serum uric acid levels , blood urea nitrogen , serum creatinine are common.
5. Hepatic function tests – Aminotransferases (AST/ALT) commonly rises in the early phases of heat stroke.
6. Cerebrospinal fluid analysis – CSF may show nonspecific pleocytosis , CSF proteins level may get elevated as high as 150mg/dl.
7. Muscle function test – Creatinine Kinase (CK) , Lactate dehydrogenase ( LDH ) , aldolase , and myoglobin are commonly released due to muscle necrosis. CK levels may exceed upto 100000 IU/ml.
Management
Principles
Rapid cooling of body
Support of failing organ systems
Heat stroke is an Medical emergency.Rapid reduction of core body temperature is the cornerstone of treatment.
Cooling of body
Two methods1. Ice water immersion
2. Evaporative cooling
Ice water immersionAdvantages:
Faster coolingNo sophisticated equipment
Disadvantages:
Vasoconstriction of skin vesselsCoronary spasmUncomfortable to patient
Evaporative coolingDone by spraying warm water over body and
blowing air
Advantages:No vasoconstriction of skin vessels
DisadvantageSlower cooling
i.v fluids initially 4 units of Normal saline in 1 hourfollowed by Ringer Lactate / D5%.
Inj. Paracetamol .1amp. IM stat.
Muscle relaxants such as Benzodiazepines and neuroleptic agents such as chlorpromazines used to inhibit shivering and as prophylaxis for seizures.
PREVENTION OF HEAT RELATED
ILLNESSES
ACCLIMATISATION2 WeeksShort periods of work every day to beginDuration and frequency lengthened after a
weekConstant vigilance during the processSevere tests of endurance avoided
Training
Always in consultation with med authPreferable in morning hrs
Clothing
Wear light , loose clothing ,made of wicking fibers. These fibers have tiny channels that wick the moisture from your skin to the outer layer of the clothing where it can evaporate more easily.
THANK YOU
top related