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Environmental pathology พยาธิวิทยาสิ่งแวดลอม
นพ.จตุวิทย หอวรรณภากร
ว.ว. (พยาธิกายวิภาค)
ว.ว. (นิติเวชศาสตร)
ภาควิชาพยาธิกายวิภาคและนิติเวชศาสตร
คณะแพทยศาสตร มหาวิทยาลัยนเรศวร
Definition
It is the study of disease caused by exposure to harmful external agents.
A. Toxic agents B. Physical damage
Toxic agents
• Smoking • Alcoholism • Drug abuse • Oral contraceptives • Environmental chemical อาจมาจากการทํางานหรือการประกอบอาชีพ (Occupational pathology or occupational disease)
– respiratory alkalosis followed by metabolic acidosis that may be fatal
• Chronic aspirin toxicity (salicylism) – headache, dizziness, ringing in the ears (tinnitus), mental confusion, drowsiness, nausea, vomiting, and diarrhea
• Analgesic nephropathy (renal papillary necrosis) • Erosive gastritis is a major cause of GI bleeding • May be implicated in Reye syndrome (fatty liver with encephalopathy) in children < 15 years old, especially with influenza and chicken pox
Cocaine
• Alkaloid extracted from Erythroxylon coca • เพิ่มการกระตุนของcathecolamineทําใหเพิ่มความดันเลือด ชีพจรเตนเร็ว รวมกับการหดตัวของหลอดเลือดโคโรนารีที่หัวใจ
• Mycotoxin alfatoxin liver cancer • Phytotoxin solanine neurotoxin • Animal toxin venoms snakes, bees tetrodotoxin puffer fish
RADIATION INJURY
Ionizing radiation Nonionizing radiation
Ionizing radiation
• Degree of injury depend on amount of radiation – Large amount (>10 Gy) severe tissue necrosis
– Moderate amount (1‐2 Gy) injury to dividing cells
– Small amount (< 0.5 Gy) gene mutation
• Cellular injury – Acute effects
• DNA damage gene instability • Protein damage necrosis
– Delayed complication • Fibrosis
– Carcinogenesis
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Fibrinoid necrosis from radiation
Raiation dermatitis
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• Acute radiation syndrome (radiation sickness) whole‐body exposure – Subclinical or prodromal <200 rem – Hematopoietic system 200‐600 rem – Gastrointestinal system 600‐1000 rem – Central nervous system >1000 rem
Acute Whole Body Radiation • LD50 @ 6 wks 2.5 to 4.0 Gy (250 to 400 rad) • Hematopoietic
– 200–600 REM – Maximum neutrophil and platelet depression in 2 wk
• Gastrointestinal – 600–1000 REM – Nausea, vomiting, diarrhea – Hemorrhage and infection in 1–3 wk
• Central nervous system – >1000 REM – Intractable nausea and vomiting – Confusion, somnolence, convulsions – death in 14–36 hr
Radiation Dosimetry • Roentgen: unit of charge produced by x‐rays or gamma rays
that ionize a specific volume of air
• RAD (radiation absorbed dose): the dose of radiation that will produce absorption of 100 ergs of energy per gram of tissue; 1 gm of tissue exposed to 1 roentgen of gamma rays is equal to 93 ergs
• Gray (Gy): the dose of radiation that will produce absorption of 1 joule of energy per kilogram of tissue; 1 Gy corresponds to 100 rad (SI unit for absorbed dose)
• REM (radiation equivalent man): the dose of radiation that causes a biologic effect equivalent to 1 rad of x‐rays or gamma rays
• Sievert (Sv): the dose of radiation that causes a biologic effect equivalent to 1 Gy of x‐rays or gamma rays; 1 Sv corresponds to 100 rem (SI unit)
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Nonionizing radiation
• UVA, UVB, UVC • Erythema and burn • Hyperpigmentation • Premature aging • Structural change of DNA
– basically a scrape – superficial epidermis is torn off by friction or force – regeneration without scarring usually occurs
• Laceration vs. Incision – a laceration is an irregular tear in the skin produced by overstretching. The wound margins are frequently hemorrhagic and traumatized
– an incision is made by a sharp cutting object. The margins of the incision are usually relatively clean
• Contusion – an injury caused by a blunt force that damages small blood vessels and causes interstitial bleeding, usually without disruption of the continuity of the tissue (cf ecchymosis)
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Abrasion wounds
Cut wounds
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Contusion or bruises
Thermal injury
• Cutaneous burn – Partial thickness
• First degree burn • Second degree burn
– Full thickness • Third degree burn
BURNS• 1st, 2nd, 3rd, 4th “Degree” • FULL vs. PARTIAL Thickness • Survival
– PERCENT of body using the rule of NINES – DEGREE (i.e., Depth) – Respiratory Tract Involvement – AGE – Speed of access to Burn Unit – Immune System (Pseudomonas, S. aureus, Candida)
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LIGHTNING/ELECTRICAL • ELECTRIC DISTURBANCES
– NEURAL – EKG
• THERMAL INJURY, depends upon a particular tissue’s RESISTANCE to electrical flow
• “LIGHTNING” MARKS
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HYPO‐THERMIA • Often in setting of homelessness or alcoholism or both –< 90ºF(35C) often fatal, assoc. w. • BRADYCARDIA • ATRIAL FIBRILLATION
HYPER‐THERMIA • HEAT
–CRAMPS: Electrolyte loss via sweat –EXHAUSTION: Water depletion and lack of cardiovascular compensation
– “STROKE”: Extensive peripheral vasodilatation, i.e., “shocky”, very serious, T>106º, over 110º have been reported, high mortality.
– HIGH ALTITUDES (>4000 m) – OBTUNDATION – INCREASED CAPILLARY PERMEABILITY – ACUTE PULMONARY EDEMA (HAPE)
BLAST INJURIES
• RELATED TO RAPID ATMOSPHERIC PRESSURE CHANGES – LUNGS – VISCERA, especially GAS filled viscera
• Rupture, Hemorrhage, etc. • IMMERSION BLAST also possible, causing more of a total body compression syndrome
DECOMPRESSION • Related to GAS SOLUBILITY in divers ascending rapidly, especially the more NON‐SOLUBLE gasses, like NITROGEN, and, to a lesser extent, XENON