WORKRELATED 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)
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

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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.