INJURY BY PHYSICAL AGENTS Nancy L. Jones, M.D. Department of Pathology

Injury by Physical Agents Injury due to ionizing radiation Injury due to ionizing radiation Diagnostic and therapeutic modalities Diagnostic and therapeutic modalities Mutagen and cell destroyer Mutagen and cell destroyer

Figure 9-16 Solar elastosis with basophilic degeneration of the connective tissue in the upper layer of the dermis. (American Registry of Pathology © 1990.) Downloaded from: Robbins & Cotran Pathologic Basis of Disease (on 17 February :49 PM) © 2005 Elsevier

Figure 9-11 Acute vascular injury with fibrinoid necrosis and edema after exposure to ionizing radiation. (American Registry of Pathology © 1990.) Downloaded from: Robbins & Cotran Pathologic Basis of Disease (on 17 February :49 PM) © 2005 Elsevier

Injury by Physical Agents Types of radiation Types of radiation Electromagnetic Electromagnetic X rays and gamma rays X rays and gamma rays High energy neutrons and particles High energy neutrons and particles Alpha and beta particles and protons Alpha and beta particles and protons

Injury by Physical Agents Ionizing radiation displaces electrons from molecules and atoms Ionizing radiation displaces electrons from molecules and atoms Alterations are transient or permanent Alterations are transient or permanent DNA is primary target in living cell DNA is primary target in living cell Direct target theory Direct target theory Indirect target theory Indirect target theory Free radical formation Free radical formation

Injury by Physical Agents Other targets include lipids in cell membranes and enzymes Other targets include lipids in cell membranes and enzymes Biologic effect may be seen in minutes or only after decades Biologic effect may be seen in minutes or only after decades

Injury by Physical Agents Roentgen (R) quantity of electrical charge produced in air by X or gamma radiation Roentgen (R) quantity of electrical charge produced in air by X or gamma radiation Radiation absorbed dose (rad) or grays (Gy) absorption of 10 4 ergs/gm of tissue Radiation absorbed dose (rad) or grays (Gy) absorption of 10 4 ergs/gm of tissue 1 centigray =100 R or absorption of 100 ergs of energy/gram tissue 1 centigray =100 R or absorption of 100 ergs of energy/gram tissue Relative biological effect x absorbed dose (gy) is expressed in Sievert (Sv) biological not physical effects of radiation Relative biological effect x absorbed dose (gy) is expressed in Sievert (Sv) biological not physical effects of radiation Curie represents disintegrations per second 1 ci = 3.7 x disintegrations/sec Curie represents disintegrations per second 1 ci = 3.7 x disintegrations/sec Linear energy transfer (LET) Linear energy transfer (LET) Relative biologic effectiveness (RBE) Relative biologic effectiveness (RBE)

Injury by Physical Agents Morphology Morphology Molecular level Molecular level Cellular level Cellular level Cytoplasmic changes Cytoplasmic changes

Radiation effects

Radiation Injury

Injury by Physical Agents Radiation effects on organ systems Radiation effects on organ systems Hematopoietic Hematopoietic Lymphoid Lymphoid Vascular changes Vascular changes Malignant transformation Malignant transformation Total body irradiation Total body irradiation Hematopoietic syndrome rad Hematopoietic syndrome rad Gastrointestinal syndrome rad Gastrointestinal syndrome rad Cerebral syndrome >5000 rad Cerebral syndrome >5000 rad

Acute Radiation Syndrome Subclinical Subclinical Whole body dosage <200 rem Whole body dosage <200 rem Mild nausea and vomiting with <1500/цL lymphs Mild nausea and vomiting with <1500/цL lymphs 100% survival 100% survival Hematopoietic Hematopoietic Whole body dosage rem Whole body dosage rem Intermittent N/V petechiae hemorrhage, nadir of PMN’s and platelets at 2 weeks<1000/цL lymphs Intermittent N/V petechiae hemorrhage, nadir of PMN’s and platelets at 2 weeks<1000/цL lymphs Infections, may need BM transplant Infections, may need BM transplant

Acute Radiation Syndrome Gastrointestinal Gastrointestinal Whole body dosage rem Whole body dosage rem N/V, diarrhea, hemorrhage and infection in 1-3 weeks, severe neutrophil and platelet ↓↓ N/V, diarrhea, hemorrhage and infection in 1-3 weeks, severe neutrophil and platelet ↓↓ <500/цL lymphs <500/цL lymphs Central nervous system Central nervous system Whole body dosage >1000 rem Whole body dosage >1000 rem Intractable N/V, confusion, somnolence, seizures, coma in 15 min to 3 hr. Intractable N/V, confusion, somnolence, seizures, coma in 15 min to 3 hr. No lymphs No lymphs

Injury by Physical Agents Mechanical trauma Mechanical trauma Shape of object causing injury Shape of object causing injury Kinetic energy discharged at impact Kinetic energy discharged at impact Organs/tissues affected Organs/tissues affected

Injury by Physical Agents Abrasions Abrasions Contusions Contusions Lacerations Lacerations Sharp injuries Incised wounds Stab wounds Chop wounds Puncture wounds Penetrating perforating

Abrasions Tissue piles up along direction of force

Contusions Hemorrhage in subcutaneous fat

Lacerations Tearing of tissue with surrounding abrasions and tissue bridges

Stab wounds Penetrate deeply into body

Incised wounds Long shallow sharp injuries without abrasions or tissue bridges

Chop wounds Sharp and blunt features

Puncture Wounds Contact and distant Gunshot wounds

Puncture Wounds

Motor Vehicle Accidents Impact with interior of vehicle or objects entering vehicle Impact with interior of vehicle or objects entering vehicle Thrown from vehicle Thrown from vehicle Trapped in burning vehicle Trapped in burning vehicle Asphyxial injury Asphyxial injury

Motor vehicle accidents

Patterns of injury modified by use or lack of use of restraints Patterns of injury modified by use or lack of use of restraints Airbag injuries Airbag injuries Severity of eternal injury doesn’t always correlate with severity of internal injury Severity of eternal injury doesn’t always correlate with severity of internal injury

Motor vehicle accidents

Aortic laceration from MVA

Injury by Physical Agents Thermal Injury Thermal Injury Thermal burns Thermal burns Cause ~ 5000 deaths/year Cause ~ 5000 deaths/year Most victims are children or the elderly Most victims are children or the elderly Scalding burns Scalding burns Chemical burns Chemical burns Hyperthermia Hyperthermia Hypothermia Hypothermia

Injury by Physical Agents Thermal Burns Thermal Burns Full thickness Full thickness White or charred, dry and anesthetic White or charred, dry and anesthetic Partial thickness Partial thickness Pink or mottled with blisters and pain Pink or mottled with blisters and pain Complications Complications Fluid shifts, infections, inhalation of toxic substances Fluid shifts, infections, inhalation of toxic substances

Thermal Injury Partial thickness burns spare adnexal structures Full thickness burns destroy adnexal structures

Thermal burns Partial thickness Full thickness

Thermal Injury Escharotomy incisions done to prevent compartment syndrome from fluid shifts due to burns

Thermal Injury Soot in nostril Inhalation injury to trachea

Thermal Injury scald burns

Chemical burns

Injury by Physical Agents Hyperthermia Hyperthermia Heat cramps Heat cramps Heat exhaustion Heat exhaustion Heat stroke Heat stroke

Injury by Physical Agents Hypothermia Hypothermia Cold exposure Cold exposure Frost bite Frost bite Direct effects due to high salt concentrations from crystallization of intra and extra cellular water Direct effects due to high salt concentrations from crystallization of intra and extra cellular water Indirect effects due to circulation disturbances Indirect effects due to circulation disturbances Gangrene of devitalized tissues Gangrene of devitalized tissues

Thermal Injury cold exposure gastric petechiae in hypothermia frost bite

Osborn wave seen in EKG in Hypothermia

Injury by Physical Agents Electrical injury Electrical injury Low voltage Low voltage High voltage High voltage Burns Burns Ventricular fibrillation Ventricular fibrillation Respiratory or cardiac center standstill Respiratory or cardiac center standstill Amperage, path through body and time of exposure important Amperage, path through body and time of exposure important

Histology of Electrical Injury

Low voltage electrical burns Small blister on thumb

High voltage electrical burns

Lightening causes high voltage injuries

Lightening Fern pattern, singed hair and fused coins seen in victims of lightening

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