WORK-WORK-RELATED HEAT RELATED HEAT

STRESSSTRESSMustafa Mustafa KhogaliKhogali

Dec.2006Dec.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 Evolution of Thermo.Reg.SysThermo.Reg.Sys

↑ ↑ H. Elimination V H. ConservationH. Elimination V H. Conservation

Survival► Maintenance of B.T 37˚CSurvival► Maintenance of B.T 37˚C

B.T. EQUILIBRIUMB.T. EQUILIBRIUM

Two Physiologic Mechanisms:Two Physiologic Mechanisms:

a.a. CardiopulmonaryCardiopulmonary

b.b. SweatingSweating

↓ ↓

Evaporation ↑SKBFEvaporation ↑SKBF

1. Factors Influencing H. S.1. Factors Influencing H. S.

Climate / Env. Conditions.Climate / Env. Conditions. Demands of work.Demands of work. Clothing.Clothing. Personal characteristics.Personal characteristics.

FACTORS MODIFYING HEAT FACTORS MODIFYING HEAT TOLERANCETOLERANCE

Physiological or pathological changes that alters Physiological or pathological changes that alters

body’s heat production or heat loss capacity modify body’s heat production or heat loss capacity modify

tolerance of hot environment:tolerance of hot environment:

1. 1. Physical Fitness (Exercise)Physical Fitness (Exercise) 2. 2. State of State of

Hydration Hydration

3. 3. State of AcclimationState of Acclimation 4. 4. EndotoxinsEndotoxins

5. 5. AgeAge 6. 6. DrugsDrugs

7. 7. OthersOthers

HEAT STRESSHEAT STRESS

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

H.S.INDICESH.S.INDICES

Rational: S=MRational: S=M±C±R-E±C±R-E EMPIRICAL : Subjective/Objective.EMPIRICAL : Subjective/Objective.

ETET

WBGT WBGT

PP44SRSR

WBGTWBGT

a)a) OUTDOOR = OUTDOOR =

WBGT = 0.7 WB + 0.2 GT + WBGT = 0.7 WB + 0.2 GT + 0.DB0.DB

b)b) INDOOR =INDOOR = WBGT = 0.7 WB + 0.3 GTWBGT = 0.7 WB + 0.3 GT

PERMISSIBLE HEAT EXPOSURE PERMISSIBLE HEAT EXPOSURE THRESHOLD LIMIT VALUES (WBGT THRESHOLD LIMIT VALUES (WBGT

°C)°C)WORK-REST CYCLEWORK-REST CYCLE

(% OF EACH HOUR)(% OF EACH HOUR)WORK LOADWORK LOAD

LIGHT MODERATE LIGHT MODERATE LIGHTLIGHT

CONTINUOUS WORKCONTINUOUS WORK 30.0 26.7 30.0 26.7 25.025.0

75 : 2575 : 25 30.6 28.0 30.6 28.0 25.925.9

50 : 5050 : 50 31.4 29.4 31.4 29.4 27.927.9

25 : 7525 : 75 32.2 31.1 32.2 31.1 30.030.0

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

HEAT STRESS: PRINCIPAL HEAT STRESS: PRINCIPAL SYSTEMIC RESPONSESSYSTEMIC RESPONSES

1.1. SweatingSweating 4.4. CNSCNS

2.2. Cardiovascular StatusCardiovascular Status5.5.HematologyHematology

3.3. Metabolic statusMetabolic status 6.6. HormoneHormone

MEASUREMENT OF MEASUREMENT OF BODY TBODY T

ORAL ToORAL To RECTAL TrRECTAL Tr TYMPANIC TtTYMPANIC Tt ESOPHAGEAL TeESOPHAGEAL Te Skin TsSkin Ts

1. HEAT DISORDERS1. HEAT DISORDERS

H.SyncopyH.Syncopy

H.CrampsH.Cramps

H.ExhaustionH.Exhaustion

H.StrokeH.Stroke

2. H.Induced Illnesses2. H.Induced Illnesses

T67 EFFECTS OF HEAT AND LIGHTT67 EFFECTS OF HEAT AND LIGHT

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

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

INTERACTING MECHANISM AND INTERACTING MECHANISM AND OUTCOME IN HEAT STROKE OUTCOME IN HEAT STROKE

PATIENTSPATIENTSMETABOLISM ENVIRONMENT

AGE, DRUGSCHRONIC DISEASES

HEAT AGAIN

VASODILATION SWEATING T

FLUID LOSS

CESSATION OFSWEATING

V V

V V V

SHOCKV V

RISE IN BODY CORE TEMPRATURE

VACIDOSIS HYPOXIA

RHABDO-MYOLSIS

MYOCARDIAL ACUTE RENAL DIC CIRCULATORY CNS

DYSFUNCTION FAILURE FAILURE

V V V

VV

HOST FACTORS REPORTED TO HOST FACTORS REPORTED TO INCREASE RISK OF HEAT STROKEINCREASE RISK OF HEAT STROKE

Lack of acclimitizationLack of acclimitization Obesity Obesity Lack of physical fitnessLack of physical fitness FatigueFatigue Lack of sleepLack of sleep DehydrationDehydration Febrile IllnessFebrile Illness Acute and convalescent infectionsAcute and convalescent infections Fever following immunizationFever following immunization Conditions affecting sweatingConditions affecting sweating Skin diseases Skin diseases Acute or chronic alcoholismAcute or chronic alcoholism Chronic diseases; e.g. diabetes, cardiovascular diseaseChronic diseases; e.g. diabetes, cardiovascular disease Lesions of hypothalamus, brainstem, and cervical part of the spinal cordLesions of hypothalamus, brainstem, and cervical part of the spinal cord Potassium deficiencyPotassium deficiency Sustained output of muscular metabolic heatSustained output of muscular metabolic heat Increased susceptibility due to biological variabilityIncreased susceptibility due to biological variability

MANAGEMENT OF HEAT MANAGEMENT OF HEAT STROKESTROKE

CRITICAL MANAGEMENT STRATEGIESCRITICAL MANAGEMENT STRATEGIES

Recognition of HyperthermiaRecognition of Hyperthermia

Rapid Effective CoolingRapid Effective Cooling

Supportive CareSupportive Care

Observation of H.R. Complications of Tissue InjuryObservation of H.R. Complications of Tissue Injury

COOLING MODALITIESCOOLING MODALITIES

1.1. Ice water immersionIce water immersion

2.2. Evaporation cooling (FANS)Evaporation cooling (FANS)

3.3. Ice packsIce packs

4.4. Lavage: peritoneal, rectal, gastricLavage: peritoneal, rectal, gastric

5.5. Alcohol sponge bathAlcohol sponge bath

6.6. Cardiopulmonary by passCardiopulmonary by pass

OBJECTIONSTO ICE WATER IMMERSIONOBJECTIONSTO ICE WATER IMMERSION

1.1. Intense peripheral vaso constrictionIntense peripheral vaso constriction

2.2. Induction of shiveringInduction of shivering

3.3. Extreme discomfort of patientExtreme discomfort of patient

4.4. Discomfort of medical attendanceDiscomfort of medical attendance

5.5. Difficulty: Cardiopulmonary resuscitationDifficulty: Cardiopulmonary resuscitation

6.6. Difficulty: Monitoring vital signsDifficulty: Monitoring vital signs

7.7. Unpleasant and unhygienic conditionsUnpleasant and unhygienic conditions

ALTERNATIVE METHODALTERNATIVE METHOD

Evaporative cooling from warm Evaporative cooling from warm skinskin

M.B.C.U.M.B.C.U.

Groups at RiskGroups at Risk

WORKERSWORKERS : In hot industries.: In hot industries.: Outdoor occupations.: Outdoor occupations.: Who wear protective : Who wear protective

clothingclothing ELDERLYELDERLY : Those with : Those with

chr.diseases.chr.diseases. EXERCISING CHILDEXERCISING CHILD

MAKKAH PILGRIMS (In hot season)MAKKAH PILGRIMS (In hot season)

Occup.H.ExposureOccup.H.Exposure

OUTDOOR: OUTDOOR: Agric./Farming;constructionAgric./Farming;construction

Cane sugar cuttingCane sugar cutting

Oil and gas drillingOil and gas drilling

Fire fighting etc.Fire fighting etc.

OCC.H.EXPOSURE--2OCC.H.EXPOSURE--2

INDOOR: BakeriesINDOOR: Bakeries

Forging/FoundriesForging/Foundries

Engine roomEngine room

Steel/Iron/Glass Steel/Iron/Glass manufacture manufacture

Laundries etc.Laundries etc.

Thermal Problems in Thermal Problems in SportSport

Outdoor sport activitiesOutdoor sport activities Mass Participation (Marathons)Mass Participation (Marathons)

(Aerobic Capacity imp)(Aerobic Capacity imp)

MAKKAH PILGRIMAGEMAKKAH PILGRIMAGE

H.Illness alert prog. H.Illness alert prog. (HIAP)(HIAP)

Strategies based on triad of Prev.Strategies based on triad of Prev. PrimaryPrimary SecondarySecondary TertiaryTertiary

PRIM.PREV.PRIM.PREV.

Adequate/Eff.Eng.DesignAdequate/Eff.Eng.Design

↓ ↓ Comfortable coolingComfortable cooling Good ventilationGood ventilation ↓↓WorkloadWorkload Education/AwarenessEducation/Awareness

SECOND.PREV.SECOND.PREV.

a)a) Preselection/AcclimationPreselection/Acclimation PE Med Ex.►Employees PE Med Ex.►Employees Preplac.Med Ex.► SportPreplac.Med Ex.► Sport

b)b) Appropriate Adm.ManagementAppropriate Adm.Management

(Work-rest cycle + Fluids)(Work-rest cycle + Fluids)

Information to PhysicianInformation to Physician

Detailed Job Description:-Detailed Job Description:-

* Length/Duration of work* Length/Duration of work

* Shift system* Shift system

* Freq./duration of rest* Freq./duration of rest

* Env.T* Env.T

Pre.Placement ExamPre.Placement Exam

a) Medical Historya) Medical History Occupational HistoryOccupational History Past History of H.R.IPast History of H.R.I Behav.habitsBehav.habits

b) Physical Exam b) Physical Exam

Tert.Prev.Tert.Prev.

Diag.H.I. SyndromesDiag.H.I. Syndromes FacilitiesFacilities Training Diff.CategoriesTraining Diff.Categories Protocol of ManagementProtocol of Management

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

PERSON.PERSON.

Alert ProgramsAlert Programs

Alert DangerAlert Danger

I. I. Permissible HeatPermissible Heat 0 0 0 0

Exposure TLVExposure TLV

II.II. Thermal LimitThermal Limit

1- Oral temperature Increase ˚c 1.51- Oral temperature Increase ˚c 1.5 2.5 2.5

2- Skin temperature Increase ˚c 3.0 2- Skin temperature Increase ˚c 3.0 4.04.0

Alert ProgramsAlert ProgramsAlert 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

H. S. TrainingH. S. Training

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

Conclusions Conclusions

a.a. Prevention of Heat illness in both Prevention of Heat illness in both

occupational and sport is crucial occupational and sport is crucial since they potentially lethal.since they potentially lethal.

b.b. Appreciation of Heat illnessAppreciation of Heat illness: : Physician/Administrator/ Param Physician/Administrator/ Param industrial & military/Organizers.industrial & military/Organizers.

c.c. Principles of Prev and Management Principles of Prev and Management

- All members of community- All members of community

ConclusionsConclusions

d. Success achieved through:d. Success achieved through: Awareness and education.Awareness and education. Acclimatization (Matching Activity Acclimatization (Matching Activity αα

T+H).T+H). Liberal Water Replacement.Liberal Water Replacement. Use of Proper clothing.Use of Proper clothing. Appropriate history of medical exam.Appropriate history of medical exam. Adoption of Heat Alert Prog.Adoption of Heat Alert Prog.