WORK-RELATED HEAT STRESS Mustafa Khogali Dec.2006

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WORK-RELATED HEAT STRESSMustafa KhogaliDec.2006
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INTRODUCTION

• Is our climatic environment a threat to our
  physiological adaptation?
• Animals are better suited!
• Humans attained sophisticated control But?
• Both are suited to risk of HEAT ILLNESS?

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Evolution of Thermo.Reg.Sys

• ? H. Elimination V H. Conservation
• Survival? Maintenance of B.T 37C

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B.T. EQUILIBRIUM

• Two Physiologic Mechanisms
• Cardiopulmonary
• Sweating
• ?
• Evaporation ?SKBF

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• 1. Factors Influencing H. S.
• Climate / Env. Conditions.
• Demands of work.
• Clothing.
• Personal characteristics.

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FACTORS MODIFYING HEAT TOLERANCE

• Physiological or pathological changes that alters
  bodys heat production or heat loss capacity
  modify tolerance of hot environment
• 1. Physical Fitness (Exercise) 2. State of
  Hydration
• 3. State of Acclimation 4. Endotoxins
• 5. Age 6. Drugs
• 7. Others

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HEAT STRESS

• Are there safe limits??
• Wide variability in Human TL.
• Complexity of H.Exchange.

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H.S.INDICES

• Rational SMCR-E
• EMPIRICAL Subjective/Objective.
• ET
• WBGT ?
• P4SR

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WBGT

• OUTDOOR
• WBGT 0.7 WB 0.2 GT 0.DB
• INDOOR
• WBGT 0.7 WB 0.3 GT

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PERMISSIBLE HEAT EXPOSURE THRESHOLD LIMIT VALUES
(WBGT C)
WORK-REST CYCLE ( OF EACH HOUR) WORK LOAD LIGHT MODERATE LIGHT
CONTINUOUS WORK 30.0 26.7 25.0
75 25 30.6 28.0 25.9
50 50 31.4 29.4 27.9
25 75 32.2 31.1 30.0
ADAPTED FROM ACGIH THRESHOLD LIMIT VALUES FOR
CHEMICAL AND PHYSICAL AGENTS AND BIOLOGICAL
EXPOSURE INDICES, 1992-1993, CINCINNATI, 1992,
THE CONFERENCE. LIGHT 200 Kcal/hr or less
Moderate 201-300 Kcal/hr Heavy above
300 Kcal/hr
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HEAT STRESS PRINCIPAL SYSTEMIC RESPONSES

• 1. Sweating 4. CNS
• 2. Cardiovascular Status 5. Hematology
• 3. Metabolic status 6. Hormone

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MEASUREMENT OF BODY T

• ORAL To
• RECTAL Tr
• TYMPANIC Tt
• ESOPHAGEAL Te
• Skin Ts

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• 1. HEAT DISORDERS
• H.Syncopy
• H.Cramps
• H.Exhaustion
• H.Stroke
• 2. H.Induced Illnesses

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T67 EFFECTS OF HEAT AND LIGHT

• T67.0 HEAT STROKE AND SUN STROKE
• T67.1 HEAT SYNCOPE
• T67.2 HEAT CRAMP
• T67.3 HEAT EXHAUSTION, ANHYDROTIC
• T67.4 HEAT EXHAUSTION DUE TO SALT DEPLETION
• T67.5 HEAT EXHAUSTION, UNSPECIFIED
• T67.6 HEAT FATIGUE, TRANSIENT
• T67.7 HEAT OEDEMA
• T67.8 OTHER EFFECTS OF HEAT AND LIGHT
• T67.9 EFFECTS OF HEAT AND LIGHT, UNSPECIFIED

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DEFINITION ( CLASSIC TRIAD )

• Heat stroke is a state of thermoregulatory
  failure characterised by
• (A) CNS Dysfunction
• (Poor limb coordination, delerium,
  convulsions, grand mal seizures and coma).
• (B) Generalised Anhidrosis
• (C) A Rectal Temperature Above 40.6 C

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INTERACTING MECHANISM AND OUTCOME IN HEAT STROKE
PATIENTS
AGE, DRUGS CHRONIC DISEASES
ENVIRONMENT
METABOLISM
V
V
HEAT AGAIN
V
V
V
SWEATING T
VASODILATION
CESSATION OF SWEATING
FLUID LOSS
V
V
V
V
V
ACIDOSIS HYPOXIA
SHOCK
RISE IN BODY CORE TEMPRATURE
RHABDO-MYOLSIS
V
V
V
MYOCARDIAL ACUTE RENAL DIC
CIRCULATORY
CNS DYSFUNCTION FAILURE
FAILURE
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HOST FACTORS REPORTED TO INCREASE RISK OF HEAT
STROKE

• Lack of acclimitization
• Obesity
• Lack of physical fitness
• Fatigue
• Lack of sleep
• Dehydration
• Febrile Illness
• Acute and convalescent infections
• Fever following immunization
• Conditions affecting sweating
• Skin diseases
• Acute or chronic alcoholism
• Chronic diseases e.g. diabetes, cardiovascular
  disease
• Lesions of hypothalamus, brainstem, and cervical
  part of the spinal cord
• Potassium deficiency
• Sustained output of muscular metabolic heat
• Increased susceptibility due to biological
  variability

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MANAGEMENT OF HEAT STROKE

• CRITICAL MANAGEMENT STRATEGIES
• Recognition of Hyperthermia
• Rapid Effective Cooling
• Supportive Care
• Observation of H.R. Complications of Tissue Injury

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COOLING MODALITIES

• 1. Ice water immersion
• 2. Evaporation cooling (FANS)
• 3. Ice packs
• 4. Lavage peritoneal, rectal, gastric
• 5. Alcohol sponge bath
• 6. Cardiopulmonary by pass

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OBJECTIONSTO ICE WATER IMMERSION

• 1. Intense peripheral vaso constriction
• 2. Induction of shivering
• 3. Extreme discomfort of patient
• 4. Discomfort of medical attendance
• 5. Difficulty Cardiopulmonary resuscitation
• 6. Difficulty Monitoring vital signs
• 7. Unpleasant and unhygienic conditions

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ALTERNATIVE METHOD

• Evaporative cooling from warm skin
• M.B.C.U.

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Groups at Risk

• WORKERS In hot industries.
• Outdoor occupations.
• Who wear protective clothing
• ELDERLY Those with chr.diseases.
• EXERCISING CHILD
• MAKKAH PILGRIMS (In hot season)

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Occup.H.Exposure

• OUTDOOR Agric./Farmingconstruction
• Cane sugar cutting
• Oil and gas drilling
• Fire fighting etc.

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OCC.H.EXPOSURE--2

• INDOOR Bakeries
• Forging/Foundries
• Engine room
• Steel/Iron/Glass
  manufacture
• Laundries etc.

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Thermal Problems in Sport

• Outdoor sport activities
• Mass Participation (Marathons)
• (Aerobic Capacity imp)

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MAKKAH PILGRIMAGE
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H.Illness alert prog. (HIAP)

• Strategies based on triad of Prev.
• Primary
• Secondary
• Tertiary

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PRIM.PREV.

• Adequate/Eff.Eng.Design
• ?
• Comfortable cooling
• Good ventilation
• ?Workload
• Education/Awareness

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SECOND.PREV.

• Preselection/Acclimation
• PE Med Ex.?Employees
• Preplac.Med Ex.? Sport
• Appropriate Adm.Management
• (Work-rest cycle Fluids)

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Information to Physician

• Detailed Job Description-
• Length/Duration of work
• Shift system
• Freq./duration of rest
• Env.T

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Pre.Placement Exam

• a) Medical History
• Occupational History
• Past History of H.R.I
• Behav.habits
• b) Physical Exam

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Tert.Prev.

• Diag.H.I. Syndromes
• Facilities
• Training Diff.Categories
• Protocol of Management

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WORK PRACTICE

• ENV.ASSESSMENT.
• PROG.OF ACCLIMATIZATION.
• ADEQUATE WATER SUPPLY.
• FIRST AID TRAINING.
• GENERAL TRAINING FOR HEALTH SAFETY.
• ADAPTIVE WORK SCHEDULE.
• WORK-REST REGIMEN
• PREPLACEMENT/PERIODICAL MED.EXAM.
• OBSERVATION/MONITORING BY TRAINED PERSON.

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Alert Programs

• Alert Danger
• I. Permissible Heat 0 0
• Exposure TLV
• II. Thermal Limit
• 1- Oral temperature Increase c 1.5 2.5
• 2- Skin temperature Increase c 3.0 4.0

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Alert Programs
Alert Danger
III. Heat Illnesses
1. Heat Exhaustion Headache Dizziness
Feeling of fatigue Insecure galt
To 38 c Confusion
Fast pulse To 38.5 c
2. Heat Stroke Disorientation Collapse
Peculiar behaviour Loss of consciousness
wanders around To 40.0 c
To 39.5 c

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• H. S. Training
• Rev. of H. S. Disorders.
• Risk factors of HRD.
• Recognition of signs or symptoms.
• Prev. measures to be used.
• Fluid replacement options.
• Expectations.

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Conclusions

• a. Prevention of Heat illness in both
• occupational and sport is crucial since they
  potentially lethal.
• Appreciation of Heat illness
  Physician/Administrator/ Param industrial
  military/Organizers.
• Principles of Prev and Management
• - All members of community

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Conclusions

• d. Success achieved through
• Awareness and education.
• Acclimatization (Matching Activity a TH).
• Liberal Water Replacement.
• Use of Proper clothing.
• Appropriate history of medical exam.
• Adoption of Heat Alert Prog.