Different types of cases related to heat in Ohc and management

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heat related illness types OHC occupational health centre management heat cramps exhaustion stroke

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https://www.cdc.gov/niosh/heat-stress/about/illnesses.html

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Heat-Related Illnesses in an Occupational Health Centre (OHC)

Workers exposed to hot environments - foundries, construction sites, mines, kitchens, agriculture - are at risk for a spectrum of heat-related conditions. The OHC must recognize, categorize, and manage each correctly.

Classification of Heat-Related Conditions

There are 6 main types, ranging from mild to life-threatening:

1. Heat Rash (Prickly Heat / Miliaria)

Cause: Excessive sweating causing blockage of sweat ducts
Symptoms:

Red clusters of small pimples or blisters
Appears on neck, upper chest, groin, under breasts, elbow creases
Itching and discomfort

OHC Management:

Move worker to a cooler, less humid area
Keep the rash area dry
Apply dusting powder to increase comfort
Avoid ointments and creams (block pores further)

2. Heat Cramps (Miner's / Stoker's / Fireman's Cramps)

Cause: Rapid dehydration with loss of water and salt through profuse sweating in high temperatures - classically seen in miners, stokers, and furnace workers.

Symptoms:

Sudden, severe, painful paroxysmal muscle cramps (arms, legs, abdomen)
Flushed face, dilated pupils
Dizziness, tinnitus, headache, vomiting

OHC Management:

IV normal saline gives rapid relief
Oral ORS / electrolyte drinks if mild
Rest in cool area
Gradual return to work after full recovery

3. Heat Syncope

Cause: Peripheral vasodilation in heat leads to pooling of blood in extremities, causing a sudden drop in blood pressure and transient loss of consciousness.

Symptoms:

Sudden fainting or near-fainting
Pale, cool, moist skin
Weak pulse; temperature is usually normal or only mildly raised

OHC Management:

Lay the worker flat, elevate legs
Move to cool area
Oral fluids once conscious
Monitor vitals; ECG if cardiac cause suspected

4. Heat Exhaustion (Heat Prostration / Heat Collapse)

Cause: A condition of collapse without a significant rise in body temperature, following exposure to excessive heat, precipitated by muscular work and unsuitable clothing. Results from loss of water and salt through excessive sweating.

Symptoms:

Extreme exhaustion and peripheral vascular collapse
Sudden weakness, dizziness, nausea
May stagger or fall
Face pale, skin cold and clammy, temperature subnormal (distinguishes from heat stroke)
Dilated pupils, small thready pulse, sighing respiration
Headache, heavy sweating, decreased urine output
No CNS impairment (core temp 37-40°C)

A dangerous variant - Hyponatremic Heat Exhaustion:

Occurs from voluntary overhydration with plain water
Can cause CNS symptoms and seizures; potentially fatal
Treat with normal saline per standard hyponatremia protocol

OHC Management:

Remove from heat source immediately
Lay flat, rest in cool environment
Oral or IV fluid and electrolyte replacement
Monitor vitals - if resolved in 20-30 minutes, educate and discharge
If symptoms persist beyond 30 minutes, treat as heat stroke
Prevent re-exposure to heat for at least 24 hours

5. Heat Stroke (Heat Hyperpyrexia / Thermic Fever / Sunstroke)

The most severe and life-threatening heat-related illness. A medical emergency with ~10% mortality.

Definition: Core (rectal) temperature >41°C (some sources >40°C) with neurological disturbances.

"Sunstroke" = heat stroke with direct sun exposure.

Types:

Feature	Exertional Heat Stroke	Classic Heat Stroke
Who	Athletes, military, laborers working hard in heat	Elderly (>60 years), chronically ill
Sweating	Present in ~50% (due to catecholamines)	Usually ABSENT (anhidrosis)
Setting	Active physical exertion	Passive heat wave exposure

Predisposing Factors:

High temperature + high humidity (at 100% humidity, even 32°C can cause heat stroke)
Lack of acclimatization
Minor infections, alcoholism, obesity
Major tranquilizers, anticholinergics, antihistamines, amphetamines (impair sweating)
Old age, pre-existing disease
Lack of air movement, unsuitable clothing

Clinical Features:

Sudden onset - collapse and loss of consciousness
Prodrome (sometimes): headache, dizziness, nausea, vomiting, weakness
Temperature 40-43°C or higher
Skin dry, hot, flushed - absence of sweating
Pupils contracted, pulse rapid (>130 bpm) and later irregular
Rapid deep Kussmaul-type breathing (>30/min)
Psychosis, delirium, stupor, coma, convulsions
When temp >42°C: vasodilation, circulatory collapse, cardiac failure
Fatal period: 5 minutes to 3 days

OHC Management (EMERGENCY - call 911 / ambulance):

Call for emergency transfer immediately
Move worker to cool, shaded area; remove outer clothing
Aggressive cooling is the primary treatment:
- Ice water immersion (15°C) is most effective
- Cold packs to axilla, groin, neck, and head
- Cooling blanket
- Wet skin and circulate air around the worker
Target: Bring core temperature to 38°C, then stop aggressive cooling (to avoid overshoot hypothermia)
Watch for shivering (counterproductive - may need benzodiazepines)
Monitoring: Use rectal/bladder/esophageal temperature probe (peripheral readings ~1°C lower than core)
Labs: Renal function, liver function, blood glucose, creatine kinase (CK), electrolytes
Monitor for complications: Arrhythmias, DIC, rhabdomyolysis, hepatic failure, renal failure (tubular necrosis)

6. Hyperthermic Anhydrosis (Desert Syndrome)

A less-commonly discussed condition, historically noted in U.S. soldiers training in deserts.

Features:

After several days of profuse sweating, perspiration suddenly stops below the neck (but persists on face and neck)
Caused by hyperkeratotic plugging of sweat glands - functional failure of sweat apparatus
Papular rashes over face and neck
Clinical features similar to heat exhaustion

Management:

Move to cool environment
Hydration and rest
Skin care for rash

Summary Comparison Table

Condition	Core Temp	Sweating	CNS Effects	Key Feature	Priority Management
Heat Rash	Normal	Excess	None	Blocked sweat ducts	Keep dry, cool area
Heat Cramps	Normal	Profuse	None	Painful muscle cramps	IV/oral saline
Heat Syncope	Normal / mild	Present	Transient LOC	Fainting episode	Lay flat, fluids
Heat Exhaustion	37-40°C	Profuse/cold skin	None	Collapse, subnormal temp	Rest, IV fluids, cool
Heat Stroke	>41°C	Absent (classic)	Severe (delirium, coma)	Hot dry skin, hyperpyrexia	Emergency cooling + ICU
Desert Syndrome	Elevated	Absent below neck	Mild	Sweat gland plugging	Cool environment, hydration

General OHC Preventive Measures

Acclimatization: Gradual exposure over 7-14 days for new workers
Hydration: Regular water/electrolyte drinks (200-250 mL every 20 minutes in heat)
Work-rest cycles: Scheduled breaks in cool areas
PPE review: Light, breathable clothing; avoid heavy PPE in high-heat areas where possible
Wet Bulb Globe Temperature (WBGT) monitoring: Combines air temp, humidity, radiant heat, and wind - better indicator of actual heat stress than temperature alone
Buddy system: Workers watch each other for early signs of heat illness
Medical screening: Flag workers with obesity, cardiac disease, diabetes, or those on anticholinergics/diuretics as high-risk

Sources:

The Essentials of Forensic Medicine and Toxicology, 36th Edition, pp. 312-313 (Heat Cramps, Heat Prostration, Heat Hyperpyrexia/Stroke)
Swanson's Family Medicine Review, pp. 812-813 (Heat Exhaustion, Heatstroke, Treatment)
NIOSH Heat-Related Illnesses - occupational guidance (updated March 2026)

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