THERMAL INJURIES--> What is Thermal injury/ death?Injury/ death which results from the effects ( direct or remote) due to localised or systemic exposure to extremes of temperature- heat or cold.

--> Classification of Thermal injuries: COLD HEAT

1. Trench foot EXTREMES OF HEAT BURNS2. Immersion foot3. Frost bite 1. Heat cramps 1. Highly heated solid body4. Neonatal cold injury 2. Heat stroke or 2. Flame burns Heat hyper pyrexia 3. Petroleum products 3. Hear prostration 4. Moist heat ( scalds) 5. Chemical burns 6. Corrosive burns Electrocution 7. Radiation injury Lightening stroke 8. Electrical injury

-->INJURIES DUE TO COLD:1. Hypothermia- Oral or axillary temperature less than 35 degree Celsius.2. Immersion foot- moist cold- can be less tolerated than other types which are “dry cold”.3. Chief target tissue are : a) Fatty tissue b) Myelinated nerve fibres c) Vascular system4. Temperature regularatory centers may get affected in hypothalamus gets affected when temperature goes below 30 degrees Celsius.5.Trench foot % Immersion foot = 5 to 8 degrees temperature+dampness6. Frost bite= Minus 2-3 degrees temperature.

7. LOCAL EFFECTS: a)Blanching and paleness of skin( vascular spasm)b) Erythema(vaso dilatation) & oedema(increased capillary permeability)c) Blister formation( dehydration )d) Necrotic changes( ischemia, arterial/capillary occlusion )

8. SYSTEMIC EFFECTS:

a)Stage-1: Patient perceives cold & shivers with fall of body temperature.

b) Stage-2: --> Shivering stops if temperature further falls. --> Patient becomes depressed, sleepy, lethargic & passes into stupor & coma. --> Partial cessation of RS, CVS, enzymatic & metabolic activities.c) Stage-3: Coma, collapse & death.9. PM FINDINGS:

a) External- Pale patches, blisters, gangrene on face and extremities.

b) Internal--> Finding ice crystals in vessels( if examined at same temperature and not otherwise ) --> bright red colour of blod --> Fatty necrosis in pancreas( HPE)

--> INJURIES DUE TO HEAT:1. Heat Cramps- Due to rapid dehydration in workers engaged at high temperature.2. Heat Hyper pyrexia- Rectal temperature more than 41 degrees Celsius. Pupils CONSTRICTED.3. Heat prostration- Collapse without increase in body temperature.

--> BURNS:1. ANATOMY OF SKIN:

2. DEGREE OF BURNS DUPUYTREN’S classification WILSON’S classification 1st degree= Only erythema 1st degree= Epidermal 2nd degree= Acute inflammation & blister

3rd degree= Destruction of epidermis 2nd degree= Dermo epidermal4th degree= Involvement of dermis

5th degree= Deep fascia & muscles 3rd degree= Deep6th degree= Bones / internal organs

3. PERCENTAGE OF BURNS Front Back

RULE OF NINES:11 compartments of 9%= 991 compartment of 1%= 01 total = 100PARKLAND’S FORMULA:( amount of I/V fluids)ADULTS:-- Per 24 hrs: TBSA x wt x 4

--1st half in 8 hrs 2nd half in 16 hrsCHILD: (24 hrs)-- 100 ml /kg- for first 10 kg-- 50 ml / kg – for next 10 kg -- 20 ml / kg – for each kg> 20CAUTION:If urine output is less than 0.5 to1.0 ml/ kg infusion rate shall beincreased.

Age Area 0 yr A= 9+1/2 B = 2+3/4 C= 2+1/2 1 yr A= 8+1/2 B = 3+1/4 C= 2+1/2 5 yr A= 6 +1/2 B = 4 C= 2+3/4 10 yr A= 5+1/2 B = 4+1/4 C= 3 15 yr A= 4+1/2 B = 4+1/2 C= 3+1/4 Adult A= 3+1/2 B = 4+3/4 C= 3+1/2 FRONT BACK

Lund & Browder Chart: A= ½ of head, B= ½ of thigh,C= ½ of one leg

--> TBSA( Total Body Surface area) affected by burn is helpful to:1. Clinical application to calculate amount of IV fluids required.2. Determine prognosis-50% or more are usually fatal.3. Surface covering trunk more fatal .

--> EFFECTS OF BURNS:1. Degree of heat- usually temperature up to 650 degrees is generated. - 1000 degrees for half to one hour( used for cremation) reduces whole body into 2-3 kg of ashes.

2. Duration of exposure- more damage with prolonged exposure.3. Percentage of burns- 50% or more are usually fatal

4. Prognosis- Poor if Head, neck or trunk is involved.5. Age- Extremes of age groups -more vulnerable

6. Sex- Females more vulnerable7. State of health- Pre exisiting disease- poor prognosis

--> CAUSES OF DEATH FROM BURNS:A. Immediate( more common)1. Primary shock: Neurogenic shock due to pain2. Secondary shock: Fluid loss--> Dehydration--> Hypovolaemic shock3. Irrespirable shock: Produced due to combustion- CO, Co2, cyanide 4. Falling of structures in case of fire in buildingB. Delayed( Less common)5. Infection & septicaemia: 36-72 hrs, Gram Negative organisms ( Pseudomonas, Clostridia Welchi etc)6. Toxemia: Due to absorption of toxic products from burnt tissue- Urea, Non proteinous Nitrogen ( NPN) substances.7. Inflammatory changes- Meningitis, Pericarditis,bronchitis, peritonotis8. Biochemical disturbances: Hypokalaemia, protein loss9. Acute oedema of glottis10. Acute renal failure- due to acute tubular necrosis C. Remote ( Rare)11. Pyaemia, gangrene, tetanus 12. Pulmonary embolism13.Jaundice 14. GIT- Hemorrhagic gastritis, Curling’s ulcer

--> POST MORTEM FINDINGS: [A] EVIDENCE OF BURNS:1. On clothes: --> Smell of inflammable medium i.e. Kerosene, petrol --> Blackening due to smoke particle deposition --> Destruction: partial / complete due to burns2. External examination of body: --> Smell of inflammable medium i.e. Kerosene, petrol --> Blackening due to smoke particle deposition --> Loosening and pealing of epidermis leading to “partial degloving” of hands and “partial destocking” of feet. --> Singeing of hair: Gross: Fragile, wrinkled, bulbous appearance of tip of hair Micro: Loss of normal contour with irregular bulbous projections on surface and irregular vacuoles in the substance( cortex).3. Internal examination of body: --> Absence of signs of ante mortem burns & --> Finding of any other cause of death- injury etc. in case of post mortem burns.

[B] EVIDENCE / SIGNS OF ANTE MORTEM BURNS: 1. On external examination of body LINE OF REDNESS BLISTERS VITAL REACTION

Due to hyperaemia due to dehydration due to cellular exudation

at the junction of Red inflamed base oedema healthy & burnt contains serous fluid areas rich in protein and Chlorides2. On Internal examination of body--> Soot ( carbon) particles- Interspersed in midst of frothy mucoid secretions in nasopharynx, pharynx, larynx, trachea and lower bronchial tree. ( May be absent ?)--> Cherry / bright red colour of blood- due to CoHb formation--> Congestion and oedema of internal organs

3. Investigations:a. Histo pathological examination of skin: --> Dmaged epidermis or/ and demis( depending on degree of burns) --> Swollen nuclei with eccentric displacement of chromatin --> Vesicle( blister)- suprabasilar / intradermal --> Hyperemia and congestion.b. CoHb Levels: --> Blood tobe collected amd sealed with liquid paraffin. --> Analysis bu Skip’s apparatus id done at FSL. --> In smokers( other than burns) level up to 10% is found. --> Level above 35-40% are conclusive for ante mortem burns.c. Enzyme Histo Chemistry: Positive for enzyme activity.[C] AGE OF BURNS:a. Redness-Immediate b. Blisters- 1 to 2hoursc. Inflammation & exudate- 6 to 12 hoursd. Drying of exudate – 12 hours e. Crust formation- 1-3 daysf. Infection and pus formation- 36 to 72 hoursg. Granulation tissue- 5 to 6 days.

[D] EVIDENCE OF PROLONGED EXPOSURE: 1. Heat Contracture Rigor mortis ( Boxing / Pugilistic attitude)a. Cause - Coagulation of proteins Depletion of ATPb. Sequence – All at a time In an orderc. Nature - Can be ante mortem Always post mortemd. Duration- Rigor mortis & other Decomposition PM changes does not follows follow/ are delayed.

2. Heat rupture Mechanical Injurya. Site- Extensor surface Any whereb. Bleeding - Absent Presentc. Floor- Intact vessels & nerves cut/ laceratedd. Vital reaction- Absent Present

3. Heat Fracture Mechanical fracturea. Cause- Increased ICT due to sharp/ blunt force steamb. Site- Sides of skull Underneath external injury above templesc. Sutures-May be crossed Not so.

4. Heat hematoma Traumatic ED hematomaa. Site- Parieto-temporal area Any whereb. Mechanism- Shrinkage of brain Sources of EDH sinus/ veinsc. Colour- Pink/ chocolate Redd. Consistency- Soft, friable Firme. Appearence- Honey comb Evenly smoothf. Neighbours- Heat effect present Heat effect absentg. CoHb- Elevated Normal5. Cooked appearance of tissues and organs/ charred : dry, hard, black,fragile.

--> MANNER AND CIRCUMSTANCES:

1. Scene of crime in spot deaths.

2. Dying declaration in hospitalised deaths/ cases.

3.Smell and type of inflammable fluid used.

4. Patten and percentage of burns

5. Association with other cause- poisoning, injury.

TRAIT DRY HEAT MOIST HEAT CHEMICAL BURNS ( SCALDS)1.Cause Flame/ heated liquid or steam corrosives/ chemicals solid body above 60 degrees 2. Site At & above At & below At & below impact area impact area impact area3. Splashing Absent present present

4. Skin dry, wrinkled & soddened & Brown, hard with charred bleached destruction5. Blisters At margins At affected area rare

6. Redline At margins At margins Absent

7. Colour Blackening Bleached Brown/ yellow / of corrosive

TRAIT DRY HEAT MOIST HEAT CHEMICAL BURNS ( SCALDS)

8. Charring Present Absent Absent

9. Singeing Present Absent Absent

10.Ulceration Absent Absent Present

11. Clothes Burnt& black Wet Brown/ yellow / of corrosive12. Soot in Present Absent Absent trachea & CoHb

13. Examples Flame burns Hot water/ milk Vitriolage

14. Common Suicidal Accidental Vitriolage manner

ELECTRICAL INJURIES

1. FACTORS AFFECTING:

A] Type of current- Alternate current (AC) is 4-5 times more dangerous than Direct current.

B] Amount of current = CV/ R Where CV= Current in Volts R= Resistance in body in Ohms. - Current up to 100 Volts is tolerable. - More than 200 Volts is usually fatal. - In India, 220-240 Volts , AC with 50 cycles per second is in use.

C] Path of current – Brain/ Heart in the path of current is more fatal.

D] Duration of flow( exposure)- Severity is directly proportionate to duration.

2. LOCAL EFFECTS:Current produces heat Normal skin Electrolysis of tissue

UlcerSkin explodes and marginsroll back on the surface and lead to CRATER formation

4.FLASH/ SPARK BURNS--> No direct contact with the conductor but burns produced due to spark from the conductor, specifically in high voltage conductors/ HT lines.--> Crocodile flash burns:A large surface of body is involved showing multiple burnt and punched out lesions.5. SPLIT BURNS--> More extensive in depth.--> Dry, hard, firm, charred area with ragged edges with aseptic necrosis of deeper tissues.6. EXIT MARK--> larger in size than entry.--> Split ridges with tissue damage.

7. POST MORTEM APPEARENCE:--> Entry and exit marks( absent if path is interrupted with bed conductor. --> No evidence if the contact surface/ s is/ are wet.

--> Internal findings:a) Of asphyxia

b) Current pearls- small balls of molten metal driven deep in to tissue near entry wound.

c) Bone pearls or Wax droppings- Calcium phosphate( in bone) get melted due to heat transmitted to bones leading to round denesity foci demonstrable radiologically.

8. HISTO LOGICAL APPEARENCE:--> Micro vesicles in the epidermis.--> “Nuclear streaming”- pyknotic epidermal nuclei with elongation and arranged in parallel or palisading alignments.--> Separation of lower dermis.--> Trans- cutaneous coagulation extending in to dermis.

9.CAUSES OF DEATH IN ELECTROCUTION:

A) Limb to head --> brain stem & upper cervical cord--> Paralysis of medulary centres of respiration.

B) Arm to Arm --> Upper cervical cord --> Paralysis of medulary centres of respiration

C) Left arm to any limb--> Heart -->Ventricular fibrillation

10. MEDICO LEGAL ASPECTS:a) Improper handling of electrical gazettes.

b) Faulty insulation in wiring.

c) Farmers pass electrical current ( illegal) in the fence to prevent entry of animals, thieves etc. The subject unknown to fact may become victim. d) Act of urination in water having electric current( also a method of torture)

:LIGHTENING STROKE:1. INTRODUCTION:--> Electrical discharge from a cloud to earth worth 1000 million Volts or more.--> Higher points are attracted.--> Electrical gazettes in “live” state also can attract.

2. TYPE OF BURNS

a)Linear: more common in moist creases.

b)ARBORESCENT or FILIGREE BURNS:Found at the path of current on superficial parts of body due to Staining of tissue by lysed red cells – fern like pattern of erythema DOES NOT CORRESPOND TO PATTREN OF VASCULAR CHANNELS.

c) Surface burns / true burns

3. CAUSE OF DEATH: same as electrocution but more severe. 4. MEDICO LEGAL ASPECTS: Thunder storm in monsoon.

:RADIATION INJURY:

1. INTRODUCTION- Decomposition of certain atoms( Thorium, Uranium, Cadmium) liberate radiant energy i.e. Alpha, beta, gamma rays etc. which converts infra red frequencies into thermal heat which causes damage to tissues.2. MODE OF EXPOSURE- a. Industrial Infra red sterilisation, nuclear energy reactors, Radio diagnosis, Radio therapy. b. Radio Immuno Assay (RIA) c. Iodine in thyroid, phosphorous in bones- cause localised irradiation.3. ACTION : Production of ions--> alter chemical structure of enzymes, cells undergoing mitosis are most sensitive ones-->leads to chromosomal damage--> abnormality of growth including neoplasms.

4. FACTORS:a. Age & sex- foetus, child, female.

b. DOSE--> 50 rads – Hematological changes possible. --> 50-100 rads - Hematological changes likely --> 100-200 rads - Mild manifestations --> 200-250 rads – Manifestations with likely mortality --> 250-500 rads – Rising mortality --> 500 rads and above – 100% mortality

c. Type of radiation: X-radiation( internal), infra redd. Rate: Shorter duration

e. Surface area exposed: Proportionate damagef. Half life of RA material: More risk with long half life

g. Type of tissue: Bone marrow, epithelial tissue

5. RADIATION SYNDROME:--> Dose less than 500 rads.--> Due to damage to nervous system--> Features: of dehydartion--> Erythema and cutaneous burns

6. DELAYED EFFECTS: Hematological, reproduction, neoplasm.

7. RADIATION AND MEDICAL MEN:A] Radiology department- Design of unit, TLD( Thermo Labile Density) tags for staff, amount of exposure in a given duration is reflected on analysis of such tags.B] Autopsy & Disposal- Dead bodies with radio activity above 5 milli-curies need special precautions as: --> Heavy rubber gloves, shoe cover, spectacle, apron- all plastic. --> Instruments with long handles. --> Avoid spillage of fluids. --> Deep burial in isolated space.