Legal Medicine - Thermal, Mechanical & Electrical Injuries PDF

**OUTLINE** I. **Generalized Heat Injuries** A. Heat cramps B. Heat exhaustion C. Heat stroke II. **Local Heat Injuries** A. Classification of burns B. Flame burns C. Scalds III. **Investigation of Death in a Conflagration** IV. **Chemical Burns** V. **Electrical Injuries** VI. *...

**OUTLINE** I. **Generalized Heat Injuries** A. Heat cramps B. Heat exhaustion C. Heat stroke II. **Local Heat Injuries** A. Classification of burns B. Flame burns C. Scalds III. **Investigation of Death in a Conflagration** IV. **Chemical Burns** V. **Electrical Injuries** VI. **Lightning Injuries** +-----------------------+-----------------------+-----------------------+ | **LEGEND** | | | +=======================+=======================+=======================+ | ⭐ | 🖊️ | 📖 | | | | | | Must | Lecture | Book | | | | | | Know | *\[lec\]* | *\[bk\]* | +-----------------------+-----------------------+-----------------------+ GENERALIZED HEAT INJURIES {#generalized-heat-injuries.TransOutline} ========================= **Usually accidental** May involve **negligence**. May be intentional in child / elderly abuse cases Medicolegal concern: Elimination of the possibility of **foul play** 3 types: **Heat cramps** **Heat exhaustion** **Heat stroke** A. HEAT CRAMPS {#a.-heat-cramps.TransSubtopic1} -------------- A.K.A. **Miner's cramp, Fireman's cramp, Stoker's cramp** Involuntary spasmodic painful contraction of muscles 🖊️due to exposure to heat Due to dehydration and **excessive loss of NaCl by sweating** Usually not fatal (very painful) Typical in those doing heavy labor in rooms with high temperatures and sweating profusely Prominent features: ⭐ **Sudden onset painful muscle cramps** Nausea, vomiting Flushed face Increased pulse rate Decreased urine production 🖊️ Because this is due to dehydration, the simple fix to heat cramps would simply be to hydrate with a normal saline solution B. HEAT EXHAUSTION {#b.-heat-exhaustion.TransSubtopic1} ------------------ **A.K.A. Heat collapse, Syncopal fever, Heat syncope, Heat prostration** Usually not fatal 🖊️ but this is more concerning compared to heat cramps because it can quite mimic rapidly fatal heat stroke Due to **failure of circulation** caused by **high environmental heat** and precipitated by muscular exertion and warm clothing Prominent features: ⭐**Sudden syncope** Headache, general body weakness, giddiness, staggering movement 🖊️ Premonitory symptoms that you usually see in heat stroke Intense thirst ⭐**Pale, cold skin** Dilated pupils, dimness of vision ⭐**Weak, thready pulse** ⭐**Core temperature may be normal or slightly elevated** 🖊️ How do you know that you're dealing with just heat exhaustion and not heat stroke? You just look for the symptoms highlighted in bold because they are in stark contrast to heat stroke 🖊️ The fix for this is to **simply remove the person or the victim from the heated environment** C.HEAT STROKE {#c.heat-stroke.TransSubtopic1} ------------- **A.K.A. Sunstroke, Heat hyperpyrexia, Thermic fever** **Collapse of central thermoregulation** due to an increase in core body temperature 🖊️ or rapid increase in body temperature, **especially in the brain** Death in **½ to 1 hour from onset** Typical scenarios: Laborers in ill-ventilated places with high environmental temperature Athletes/workers under direct sun exposure Elderly during heat waves Infants left in motor vehicles 🖊️ You can see how a generalized heat injury such as heat stroke which is usually accidental might easily be actionable and be of medicolegal concern like the laborers in ill-ventilated places, there might be some labor standard violations there, or infants left in motor vehicles there might be on child abuse and neglect there, as forensic physicians/medico-legal officers this is something you have to probe. Prominent Features: ⭐**Sudden rise in core body temperature to \>40 degrees Celsius** Premonitory: Headache, general body weakness, giddiness, staggering movement ⭐ **Dry flushed skin** ⭐ **Full and pounding pulse** Irregular respiration Constricted pupils ⭐ **Delirium, seizures, coma** II. LOCAL HEAT INJURIES {#ii.-local-heat-injuries.TransOutline} ======================= A. CLASSIFICATION OF BURNS {#a.-classification-of-burns.TransSubtopic1} -------------------------- DEPTH AND EXTENT OF BURNS The depth and extent of burn injury may not be as clear as the injury progresses in the **first 24-48 hours** 🖊️ **revisit the patient after 24 to 48 hours** the injury may not be more severe or more extensive. **\>20% TBSA** cause systemic physiologic derangements through various proinflammatory mediators **\>33% of TBSA** involved considered fatal (unless treated) 🖊️ Nowadays because of modern medicine, even if there is more than 33 percent of total body surface area involvement, they don't usually die unless you leave them untreated. However according to Solis, this percentage is already a fatal injury A person and a baby Description automatically generated Figure 1. Body Surface Area Estimation for ≥ 2^nd^ degree burns FIRST DEGREE BURNS {#first-degree-burns.TransSub-subtopic2} ------------------ **A.K.A. Sunburns** Thermal penetration ⭐ limited to **epidermis** Dermis and all elements of its appendages remain intact ⭐ Skin regeneration typically within **5 to 10 days** Damaged epidermal layer desiccates and sloughs off 🖊️ from a forensic standpoint, it's important to know the **expected time when healing or skin regeneration** happens because you might be asked how long these injuries to heal and that goes into determining the question of whether safe or say for instance the **proper charge would be a serious physical injury or less serious physical injuries or slight physical injuries** Prominent features: Erythematous Blanches with touch ⭐ **Painful** 🖊️ because your nerve sensory are intact ⭐ **Does NOT blister** SECOND DEGREE BURNS {#second-degree-burns.TransSub-subtopic2} ------------------- A.K.A. **Partial thickness burns** ⭐ Extends into the **dermis** Prominent features: Erythematous Blanches with touch ⭐ **Moist** ⭐ **Blisters** pink raw base which becomes red in \~6 hours Classified as: [SUPERFICIAL PARTIAL THICKNESS (SPT) BURN] ⭐ Extends to the superficial layer of the dermis 🖊️Better healing than deep partial thickness Spontaneous reepithelialization From the margins and epithelial remnants ⭐Typically complete in **14 days (up to 3 weeks)** Discoloration and scarring can occur 🖊️ Prognosis and healing can be good Prominent feature: ⭐ **Tends to be more painful than DPT burns** 🖊️ because you have more sensory nerves that are intact [DEEP PARTIAL THICKNESS BURN] ⭐ Extends to deep dermal layer May heal spontaneously, but the rate and quality of that healing is often poor **(3-9 weeks)** Higher propensity to convert to full-thickness burns, develop infections, and form contractures 🖊️ Important to note from a medicolegal standpoint because you'd like to know, you'd be like to be able to prognosticate for the court, prosecution, and defense the extent of the injury, just how long will it take for these types of injuries to heal plus the possibility of a deformity occurring which if it happens, would automatically make the injury a serious physical injury. Prominent feature: Tend to be **less sensate due to the damage to the sensory elements** THIRD DEGREE BURNS {#third-degree-burns.TransSub-subtopic2} ------------------ A.K.A. Full-thickness burns ⭐ Extends to the **subcutaneous fat** Epidermal and dermal elements are destroyed Spontaneous wound closure takes place by **contracture formation** from the wound edges 🖊️ You don't expect reepithelialization here, expect a deformity. Scars as a rule Prominent features: ⭐ I**nsensate** 🖊️ Sensory nerve endings are destroyed ⭐ **Appears leathery and dry** Absence of tissue edema If left untreated, will form a classic burn eschar FOURTH DEGREE BURNS {#fourth-degree-burns.TransSub-subtopic2} ------------------- Extensive thermal destruction of **subcutaneous tissue, fascia, muscles, and bone** ⭐ **Charred in appearance** B. FLAME BURNS {#b.-flame-burns.TransSubtopic1} -------------- [CHARACTERISTICS OF A FLAME BURN] Varies from simple erythema to complete carbonization of the body - 🖊️ depending on the depth/severity of the burn Usually with singeing of hair and carbon deposits on the burnt area - 🖊️ because the burn is secondary to a flame/fire Generally, no demarcation line between the burnt and unburnt area Clothing in burnt areas is also burnt Burns occur at or ABOVE the site of contact of the flame [FACTORS INFLUENCING THE EFFECT ON THE BODY:] Severity of heat and duration of contact TBSA involved Depth of wounds Portions of the body involved - 🖊️ Face and trunk burns are treated more seriously compared to limbs Sex - 🖊️ ⭐male gender tends to withstand flame burn injuries better than women Age - 🖊️ ⭐ Adults can withstand better than elderly and children C. SCALDS {#c.-scalds.TransSubtopic1} --------- Tissue destruction by **moist heat** Injuries produced by the application of **hot liquids or gases to the body surfaces (**i.e boiling water or steam) Not as severe and fatal as flame burns 🖊️ for example, as boiling water is poured over the body, heat dissipates, so that's why it's not as severe, liquids generally don't retain that much heat or generate heat as a flame Death is usually due to **septic complications** [CHARACTERISTICS OF SCALDS:] ⭐ **"Geographical lesion"** - 🖊️ has **clear demarcation lines** between the burnt area and the unburnt area - Occur at or **BELOW** the site of the contact of the liquid ⭐ May be located in covered portions of the body **without affecting the clothing** No singeing of hair No soot on the skin Typically, does not result in fourth-degree burns Internal injuries are rare unless inhaled or ingested [FACTORS THAT AFFECT THE DEGREE OF TISSUE DESTRUCTION:] Severity of heat and duration of contact - Water at **60 degrees Celsius** can cause full-thickness burns in **3 seconds** Scalding agent - Thick soup and sauce, cooking oil and grease - 🖊️ can be as hot as 2000 degrees Celsius, and molten metal tends to cause deep burns - 🖊️ Different agents would retain heat at different levels Scalds under light clothing tend to be worse than on exposed skin areas - 🖊️ Light clothing retains heat more SUICIDAL or HOMICIDAL or ACCIDENTAL {#suicidal-or-homicidal-or-accidental.TransSub-subtopic2} ----------------------------------- **Usually accidental**, rarely homicidal or suicidal Accidental Injuries are predominantly "spill injuries" - 🖊️ or ⭐ **spill pattern injuries** Intentional scalding is seen in **child or elder abuse** 🖊️ pattern of abuse is forced immersion The most common intentional thermal injury in children #### SPILL PATTERN {#spill-pattern.TransSub-subtopic3} 🖊️ What you see in accidental scalding **Irregular margins** **Irregular depth**  Figure 2. Spill pattern in scalds #### FORCED IMMERSION PATTERN {#forced-immersion-pattern.TransSub-subtopic3} ⭐ Limbs: "**glove and stocking" pattern** ⭐ Trunk: often **symmetrical** involving left and right limbs equally with clear demarcation Uniform depth of scald 🖊️ unlike in spill patterns There may be sparing of areas of folded skin Sparing of areas where the child might have been gripped by the perpetrator 🖊️ or the skin might be in contact with a cold surface area 🖊️ for instance, a child was forcibly immersed in hot water in a bathtub, you would expect a clear demarcation line just where the water has been in contact with the skin only. Gluteal cleft can also be spared because it's a folded skin, and the most independent portion of the butt might also be spared if it also comes into contact with the bottom of the bathtub. This is a red flag we don't see this to be accidental, and might have to report as suspected child abuse. A baby in a womb Description automatically generated with medium confidence Figure 3. Forced immersion in a child III.INVESTIGATION OF DEATH IN A CONFLAGRATION {#iii.investigation-of-death-in-a-conflagration.TransOutline} ============================================= - Hours of exposure to temperatures over 1000 degrees - Celsius is typically required to cremate a human body - Children, clothed, fatty people burn faster - Most set fires on a body and most house fires do not achieve those conditions, even with accelerant use - 🖊️ gas, kerosene - Regardless of the severity of surface destruction, **organs are usually well-preserved** enough for a meaningful autopsy A. PARTICULAR AUTOPSY CONSIDERATIONS {#a.-particular-autopsy-considerations.TransSubtopic1} ------------------------------------ - 🖊️not particularly for investigation of death in a conflagration, but can be challenging in this situation - **Who is the victim?** - 🖊️challenging because the whole body might be charred. - **Was the victim alive at the time the victim was burned?** - 🖊️ The victim might be a victim of a homicide and not an accidental fire - If alive, why couldn't the victim escape the fire? 🖊️there might be certain aspects that would render the victim incapable of escaping, maybe the victim was intoxicated, the victim has a physical debility or medical condition - **What is the cause of death?** - 🖊️matter of concern in death in a conflagration, because the victim might have died in a homicidal injury and not a fire - **Are the injuries ante-mortem or post-mortem?** - 🖊️are the injuries due to antemortem injuries or merely artifacts of thermal injury? Because there are certain artifacts or changes in the body that are due to the fire due to exposure to the fire or heat that might be mistaken or simulate antemortem injuries, this would have to be ascertained by a medicolegal officer - **Is there anything that may indicate a possible cause of the fire?** - 🖊️Suicidal? Homicidal? Accidental? - **Site of origin of the fire?** - 🖊️ There can be tell-tale signs in the body that can suggest where the fire is coming from. Based on the where is the maximal effect seen on the body relative to the other objects in the scene? B. ESTABLISHING THE IDENTITY OF THE VICTIM {#b.-establishing-the-identity-of-the-victim.TransSubtopic1} ------------------------------------------ - **Personal effects** - ID, jewelry, clothing, footwear, property in the pockets - **Sex, age, color of hair** - 🖊️only as presumptive identification. The color of hair may change in exposure to high heat, although black hair remains black at any rate - Weight, height, color of eyes: **UNRELIABLE** - 🖊️ Exposure to fire for a long period of time, the body would **desiccate or shrink**. The color of the eyes won't be appreciated because of coagulation of proteins in the cornea - **Fingerprint** - 🖊️if fingers are not charred. If it desiccated, you could just soak it in water and recover the fingerprints from there - **DNA** - 🖊️ The best place to recover may be in the bone marrow - ⭐**Teeth\*** - 🖊️ Very reliable, definitive identification due to high resistance to fire - **Natural disease or stigmata** - Scars, tattoos, old deformities, injuries, old surgeries, implants and prosthesis C.CAUSES OF DEATH IN RELATION TO CONFLAGRATION {#c.causes-of-death-in-relation-to-conflagration.TransSubtopic1} ---------------------------------------------- - **Immediate:** - Neurogenic shock - Concomitant physical injuries - Asphyxia - 🖊️from carbon monoxide or inhalation of noxious gas that is generated in a fire, or glottis closing because of inhalation of very hot gases - **Delayed:** - Hypovolemic shock - Acute lung Injury - 🖊️ Inhalation of noxious hot gases - Renal failure - 🖊️ Dehydration and widespread tissue destruction - Hypothermia - Sepsis, pneumonia SUICIDAL or HOMIDICAL or ACCIDENTAL {#suicidal-or-homidical-or-accidental.TransSub-subtopic2} ----------------------------------- - ⭐Usually accidental, but occasionally homicidal or suicidal - **Suggestive of accidental origin:** - Children, mentally deficient persons, and intoxicated individuals - Natural disease that may cause collapse (e.g. stroke, epilepsy, myocardial infarction) - **Suggestive of homicidal intent:** - **Teeth are charred** but internal organs are significantly less burnt - 🖊️if there is a patchy scarring especially on the head, trying to conceal the identity of the victim - **Patchy charring:** suggests the use of accelerants - **Unburnt patch over wrists/ankles:** may suggest the victim was bound before the fire started - **An unburnt horizontal and strap-like patch over the neck** suggests ligature strangulation D.INDICATIONS OF THE VICTIM WAS ALIVE WHEN BURNED {#d.indications-of-the-victim-was-alive-when-burned.TransSubtopic1} ------------------------------------------------- - **Vital reaction in burnt areas.** - 🖊️It means that there was **circulation** when the burning was happening. - 🖊️⭐Do note however that a victim may be alive when burned but there are no vital reactions in the burn areas. That's when the burning might have **occurred way too soon or way too fast,** so the body is unable to mount a vital reaction in time. - E.g., Dermal erythema, edema, blister formation, hemorrhage - **Carboxyhemoglobin in the blood** - Cherry red appearance and lividity - 🖊️You should probe deeper because it's said that you will be able to appreciate the cherry red appearance in lividity with carbon monoxide saturation as low as **30%** and it is said to be not good enough evidence of the victim being alive when burned - **≥50% CO saturation**: good evidence - Frequent absence in victims of flash fire - 🖊️Do note however that the victim may be alive when burned even if the carbon monoxide saturation is lower than 50% or even lower than 30% because this is frequently absent in **victims of flash fire.** - 🖊️So in victims of flash fire **you don't see increased carboxyhemoglobin in their blood** - 🖊️E.g., mga pagawaan ng fireworks - ⭐**Soot in the airways, esophagus, stomach** - 🖊️ Is said to be ⭐**incontrovertible evidence** that the victim was alive when burned because this tells us that the victim was ⭐**breathing** when she/he was burned. The only way for soot to come down to your airways is if there is inhalation. E. ARTIFACTS OF THERMAL INJURY {#e.-artifacts-of-thermal-injury.TransSubtopic1} ------------------------------ - 🖊️There are a lot of changes to the body that would be due to simply it being exposed to the fire or being exposed to the heat from the fire and the medicolegal doing the autopsy should be able to differentiate those from actual antemortem injury - **Blackening of the body surface** - **Singeing of hairs** - 🖊️ Whether or not the victim was alive at the time of the fire the skin will be blackened because of the carbon deposits and the hair will be singed by the fire - **[Heat stiffening]:** ⭐ **"Pugilistic attitude" or "Fencing posture"** - 🖊️ Often seen in **victims of conflagration** - 🖊️ Due to the contracture of the muscles or the desiccation of the muscles and the denaturation of the proteins - 🖊️ Because the **flexor muscles are generally stronger**, the tendency is for the limbs to flex when exposed to prolonged heat or to fire that's why is said to have a pugilistic attitude because the arms would be flexed, the lower libs would likewise be flexed, and the fingers are also expected to be flexed that they would look like they would box somebody, hence pugilistic attitude. - 🖊️ This would not settle. **Until the onset of decomposition** - **Skin, muscle, and subcutaneous splits** - Exposure of internal organs - 🖊️Particularly in the abdomen - 🖊️Might be mistaken for antemortem lacerations or antemortem stab wounds or incisions. The way to differentiate them from that would be: - **Location** - 🖊️Seen over the head, over the extensor surfaces of the limbs, over or around joint areas, and across the abdomen. - Orientation with respect to the myofibers - Tend to follow the **orientation of the muscle fibers** so they're parallel to that. - When you see what looks like a **split perpendicular to the direction of the muscle fibers**, don't think artifact of the thermal injury. Think this might have been an antemortem injury whether a laceration or a stab wound or an incised wound. - **Tongue protrusion** - **Breast shrink, erect, and increase in firmness.** - **"Heat fractures"** - ⭐Commonly over the temples, sometimes bilateral - 🖊️sometimes unilateral - Characteristically consists of several lines radiating from a **common center** - **Does not originally involve sutures.** - Commonly **outward bursting** with protrusion of brain tissue - Also seen in the long bones of the limbs - 🖊️due to the pull of the shrinking muscles due to desiccation - 🖊️After the body is exposed to the heat for a long period of time and now is cooling down that's when these heat fractures typically occur. - **Fluid may collect between layers of the skin.** - Skin in the hands and feet may detach as gloves 🖊️or stockings. - **Brain and spinal cord shrunken** (firm and yellow to light brown due to cooking) - Blood expressed accumulates in **epidural space** **(⭐"heat hematoma)** - 🖊️Must be differentiated from an actual antemortem epidural hematoma - 🖊️**⭐**The heat hematoma typically looks spongy, foamy, and red-brown whereas the actual antemortem epidural hematoma looks more uniform, smooth, not spongy, deep red. - **Lungs shrunken** - Blood is expressed in the airways, alveolar space, mouth, and nostrils. - 🖊️One must be careful not to immediately consider this as evidence of antemortem trauma - **Dilation of the anus** - 🖊️Why do we take note of this? The dilation happens because of the shrinkage of the perianal soft tissues. - 🖊️Why do we know that this can happen in case of death in a conflagration? Because you **⭐** might mistake it for evidence of sodomy. Just because the anus is dilated doesn't mean that the victim was sodomized. IV.OTHERS {#iv.others.TransOutline} ========= A. CHEMICAL BURNS {#a.-chemical-burns.TransSubtopic1} ----------------- - "Corrosive burns" - Burns due to strong acids and alkalis and other irritant chemicals interacting with the molecular structures of the tissues. - E.g., sulfuric acid, nitric acid, hydrochloric acid, caustic soda, potash, Lysol, etc. - **⭐**Usually accidental but may be intentional. - When suicidal, typically by **ingestion** FACTORS AFFECTING THE DEGREE OF TISSUE DESTRUCTION {#factors-affecting-the-degree-of-tissue-destruction.TransSub-subtopic2} -------------------------------------------------- - **pH of the offending agent** - **⭐alkali more destructive than acids** in general (except hydrofluoric acid) - 🖊️**Alkalis=liquefactive necrosis, Acids=coagulative necrosis.** When the acids cause coagulative necrosis, the coagulant, the denatured proteins of the soft tissues, tend to halt the further penetration of the acid. That's why it is less destructive than an alkali. - **The concentration of the offending agent** - **Duration and volume of contact** - **The extent of irrigation** - 🖊️If one were able to irrigate immediately the area that came in contact with the chemical, then you might expect less tissue destruction. GENERAL CHARACTERISTICS OF CHEMICAL BURNS {#general-characteristics-of-chemical-burns.TransSub-subtopic2} ----------------------------------------- - **"Geographic lesion"** - **No vesication** - 🖊️Compared to heat injuries, you don't see vesication typically in chemical burns. You see them in flame burns, scalding, particularly in the case of second-degree burns. - Staining of the skin or clothing by the chemical - Presence of chemical substance - Ulcerative patches of the skin - 🖊️In chemical burns, the tendency is **to ulcerate** and not to blister - Inflammatory redness of the skin surface - Delayed healing (increased risk of scarring and keloid formation) - 🖊️Because of the retained chemicals in the soft tissues CHARACTERISTIC LESIONS BY DIFFERENT CHEMICALS {#characteristic-lesions-by-different-chemicals.TransSub-subtopic2} --------------------------------------------- - Sulfuric acid **(A.K.A. Oil of Vitriol)** - Very destructive - **Blackish-brown sloughs** - Nitric acid - **Yellow, yellowish-brown, or brown** slough - Destroys clothing - Hydrochloric acid - Not as destructive as sulfuric acid and nitric acid - Localized red or reddish-gray ulcerations - Caustic soda (NaOH) or Caustic Potash (KOH) - Bleached appearance and greasy feeling to the skin - Becomes brown or parchment-like B. ELECTRICAL INJURIES {#b.-electrical-injuries.TransSubtopic1} ---------------------- - Electrocution produces high-temperature burns - Variety of effects - **⭐**External signs of injury **can be deceptively benign compared to the extent of soft-to-tissue damage** - 🖊️When it comes to electrical injuries, the external injuries might be benign and they have very severe internal injuries. You might have **very small electrical burns on the surface of the skin and yet you have a dead victim**, or you might have extensive burn injuries to the skin but the victim is alive - Mostly accidental - **High voltage:** \>1000 V - **Low voltage:** \