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WORK-RELATED HEAT STRESS Mustafa Khogali Dec.2006

WORK-RELATED HEAT STRESS Mustafa Khogali Dec.2006. 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?. Evolution of Thermo.Reg.Sys.

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WORK-RELATED HEAT STRESS Mustafa Khogali Dec.2006

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  1. WORK-RELATED HEAT STRESSMustafa KhogaliDec.2006

  2. 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?

  3. Evolution of Thermo.Reg.Sys • ↑ H. Elimination V H. Conservation • Survival► Maintenance of B.T 37˚C

  4. B.T. EQUILIBRIUM • Two Physiologic Mechanisms: • Cardiopulmonary • Sweating ↓ Evaporation ↑SKBF

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

  6. FACTORS MODIFYING HEAT TOLERANCE • Physiological or pathological changes that alters body’s 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

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

  8. H.S.INDICES • Rational: S=M±C±R-E • EMPIRICAL : Subjective/Objective. ET WBGT  P4SR

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

  10. 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

  11. HEAT STRESS: PRINCIPAL SYSTEMIC RESPONSES • 1.Sweating4.CNS • 2.Cardiovascular Status5.Hematology • 3.Metabolic status6.Hormone

  12. MEASUREMENT OF BODY T • ORAL To • RECTAL Tr • TYMPANIC Tt • ESOPHAGEAL Te • Skin Ts

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

  14. T67 EFFECTS OF HEAT AND LIGHT • T67.0HEAT 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

  15. 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

  16. 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

  17. 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

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

  19. 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

  20. 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

  21. ALTERNATIVE METHOD • Evaporative cooling from warm skin • M.B.C.U.

  22. 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)

  23. Occup.H.Exposure • OUTDOOR: Agric./Farming;construction Cane sugar cutting Oil and gas drilling Fire fighting etc.

  24. OCC.H.EXPOSURE--2 • INDOOR: Bakeries Forging/Foundries Engine room Steel/Iron/Glass manufacture Laundries etc.

  25. Thermal Problems in Sport • Outdoor sport activities • Mass Participation (Marathons) (Aerobic Capacity imp)

  26. MAKKAH PILGRIMAGE

  27. H.Illness alert prog. (HIAP) Strategies based on triad of Prev. • Primary • Secondary • Tertiary

  28. PRIM.PREV. • Adequate/Eff.Eng.Design ↓ • Comfortable cooling • Good ventilation • ↓Workload • Education/Awareness

  29. SECOND.PREV. • Preselection/Acclimation • PE Med Ex.►Employees • Preplac.Med Ex.► Sport • Appropriate Adm.Management (Work-rest cycle + Fluids)

  30. Information to Physician • Detailed Job Description:- * Length/Duration of work * Shift system * Freq./duration of rest * Env.T

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

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

  33. 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.

  34. 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

  35. Alert Programs

  36. 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.

  37. 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

  38. Conclusions d. Success achieved through: • Awareness and education. • Acclimatization (Matching Activity α T+H). • Liberal Water Replacement. • Use of Proper clothing. • Appropriate history of medical exam. • Adoption of Heat Alert Prog.

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