Chemical Burns & Radiation Injuries

1. Chemical Burns & Radiation Injuries Moritz Haager Dec. 04, 2003

2. Objectives • Approach to chemical burns • Acids, alkali, HF • Approach to radiation injuries • Chemical & nuclear warfare agents

3. Perspective • > 65,000 chemicals in use; 60,000 new ones added yearly • Impossible to know each of these • Health effects mostly unknown • Important to have a general approach • Know the common agents • Important to make use of MSDS sheets & Poison Centers

4. Chemical Exposure • Dermal • Ocular • Inhalation • Ingestion • Systemic effects

5. Determinants of injury severity • Chemical agent(s) • Duration of exposure / Penetration • Concentration & pH • Type of exposure

6. Acids Coagulation necrosis Coagulate proteins forming barrier to further penetration More superficial burns Tissues have intrinsic acid buffering capacity Strong acids have pH < 2 Alkali Liquefaction necrosis Combine w/ proteins & saponify lipids Deep ongoing tissue penetration Difficult to access with hydrotherapy Strong bases have pH > 11 Acids vs. Alkali

7. General Approach • Prehospital • ED care • Post-ED care

8. Pre-hospital Management • Scene safety • Remove pt from danger • ABC’s & primary survey • Immediate decontamination • Remove contaminated clothing • Brush off dry chemicals first • Copious low pressure irrigation • Identify agent(s) & obtain MSDS sheets if possible

9. ED Care • Continue hydrotherapy • Strong acids: 2-3 hrs • Strong alkali: 12 hrs or more!! • Copious amounts to offset any exothermic reaction & maximally dilute • Low pressure to prevent spray contamination

10. ED Care • Provide analgesia • Antibiotic prophylaxis & Tetanus prn • Identify & Tx Systemic Sx • Poison center consult to guide ongoing management

11. Case 1 • 12 mo M spilled “Resolve” multi-purpose cleaner on his leg • Mom did not notice for ~15 min • Presents w/ obvious erythema and areas of excoriation on R ant leg & R wrist • Also lips red & cracked • No stridor, wheeze, or resp distress • Vitals normal, rest of exam normal

12. Case 1 • MSDS sheet: • Ethylene glycol monobutyl ether, trisodium phosphate, nonoxynol-10 • pH 12.0

13. Case 1 • Management • Flush, flush, flush • Observe cautiously for airway involvement • IV placed for analgesia & possible airway management • Lytes incl. Mg, Ca • PADIS consult (prior to obtaining MSDS)

14. Case 2 • 17 yo M comes in c/o severe pain in all digits of his hand worsening since y/d • Cleaning rusty bicycle chain with rust cleaner y/d • Indurated, tough, whitish finger tips

15. Hydrofluoric Acid • Found in rust cleaners, metal cleaners • Also used for glass etching & electronics manufacturing • Dilute solutions penetrate deeply & cause delayed Sx onset & more severe burn; pain can last days • 14.5% w/v  immediate Sx • 12% w/v  Sx w/in ~ 1hr • < 7% w/v  hrs before Sx develop

16. Hydrofluoric Acid • Mechanism of Injury • Corrosive burn (H+ ions) • Chemical burn (Fluoride ions) • Penetrate tissue & form insoluble salts w/ Mg2+ & Ca2+ • Local (tissue destruction & necrosis) & systemic effects (hypocalcemia, hypomagnesemia, hyperkalemia)  arrhythmias • Concentrated HF (>50%) to 2.5% BSA has been fatal

17. HF: Approach • Determine type & timing of exposure • Concentration & contact time • Rule out co-exposures • Rule out & monitor for systemic effects • Cardiac monitor • Trousseau’s & Chvostek’s signs, tetany • Lytes, Ca2+, Mg2+, ECG (QT) • Tx for local & systemic toxicity

18. HF: Local Treatment • Copious irrigation 15-30 min • Persistent pain indicates deep penetration  need to eliminate Fluoride ion • Debride blisters & necrotic tissue • Fluoride chelation • Ocular burns • sterile water or saline irrigation (may need local anesthetic drops) • Persistent pain  1% calcium gluconate irrigation (10% solution in 10x volume of NS) • Inhalation burns • 100% oxygen by mask, 2.5% calcium gluconate by nebulizer • Watch for pulmonary edema • Ingestions (Usually fatal) • Consider gastric lavage with calcium chloride (i.e., 20 mmol calcium in 1000 cc NS) if early presentation • Intubate prior to lavage

19. Fluoride Chelation: Calcium gluconate* • Topical gel • 2.5% = 10% Ca gluconate in 3x volume of muco or KY jelly e.g. 25 ml in 75 ml muco) in latex glove – persistent pain after 30 min indicates need for SC or intraarterial Ca2+ • Wear glove for 24 hrs • SC infiltration of 5-10% Ca gluconate at 0.5 ml/cm2 • Consider regional anesthesia b/c severe pain • Intraarterial infusion • 10 ml 10% Ca gluconate in 50 ml D5W over 4 hrs into radial or ulnar artery; repeat if pain persists / returns within 4 hrs • 20 ml of 20% Ca gluconate in 80 ml D5W; repeat in 12 hrs prn • Watch for pain, arterial spasm, thrombosis  tissue necrosis and digit loss have occurred following extravasation of calcium salts • *NB: KCL is more irritating & damaging therefore use Ca gluconate

20. HF: Systemic Treatment • Evidence of hypocalcemia • 10 ml of 10% CaCL IV empirically • Repeat prn • Follow w/ serial lytes & ECG until normalizes

21. Case 3 • 24 yo F grad student spilled phenol on her sleeve – brief rinse then continued to work • Presents feeling lightheaded, nauseated, and drowsy

22. Phenol • Aromatic acidic alcohol • Plasticizer, antiseptic, used for DNA extraction in labs • Dilute solutions less likely to cause papillary necrosis therefore tend to penetrate more quickly • Locally causes acidic burn • Systemic absorption leads to CNS depression  coma & resp arrest, as well as hypotension, metabolic acidosis, hypothermia

23. Phenol: Treatment • Copious irrigation • Polyethylene glycol 200 or 400 or isopropyl alcohol most effective, but can use water (just use LOTS) • PEG can be used for ocular exposures • Physiologic support for systemic Sx • Tx in well ventilated room

24. Case 4 • You are w/ MSF in the jungles of Cambodia • A young boy is brought in w/ severe burns after a friend stepped on unexploded ordinance which then blew up in a brilliant white flash killing his friend and showering him with burning debris

25. Phosphorus • Waxy yellow solid; spontaneous ignition in air > 34oC • Used in munitions, insecticides, rodenticides, & pesticides • Will continue to burn on skin • Firebombing of Dresden in WWII • Primarily causes thermal burns • Systemic effects metabolic in nature • Hypocalcemia, hyperphosphatemia  bradyarrhythmias

26. Phosphorus • Treatment • Submerse affected areas in COOL water, or cover in wet towels • Wash off w/ 5% Na bicarb & 3% CuSO4 in 1% hydroxyethyl cellulose solution • Phosphorus particles turn black • Phosphorus particles fluoresce under UV light

27. Highlights • Formic acid • Bicarb for acidosis, may need HD or exchange transfusions for systemic toxicity • Anhydrous ammonia • Alkali burns • High danger of inhalational injury • Elemental metals • Na+ & K+ react w/ water to produce heat & H2 gas & OH- • Remove metal fragments & place in mineral oil or isopropyl alcohol (Na+) or terbutyl alcohol (K+)

28. Part II: Chemical Warfare Agents

29. Why we should know this • Increased potential for terrorist use • Relatively easy to make or obtain • Most are simple derivatives of precursor compounds in manufacture of plastics, pesticides, & fabrics • Non-traditional chemical agents can be used as weapons in the right setting • Bhopal – methyl isocynate (2000 dead)

30. Chemical Warfare Agents • Choking (pulmonary) agents • Chlorine, Phosgene • Vesicants (Blister agents) • Mustards, halogenated oximes • Nerve agents • G agents (Sarin, tabun, soman), VX • Cyanide agents • Improvised agents

31. Vesicants • 3 subclasses • Mustards • Arsenicals • Halogented oximes • Produce cutaneous, ocular, mucous membrane, & pulmonary burns • Less lethal (primarily kill via pulmonary involvement) but highly morbid • Effects tend to be delayed • Easy to manufacture or obtain

32. Mustard Agents • Sulfur mustard = prototype • Designated H, or HD • Easy & inexpensive to produce • Most dangerous agent in WWI • Low lethality (1-3%) but high morbidity • Most recent use by Iraq in Iran-Iraq war • Low volatility, high persistence • Delayed Sx onset (may take up to 12 hrs)  prolonged exposure

33. Mustard: MOA • “Radiomimetic” • Contaminates environment • Penetrates clothing & skin easily w/o visible or perceptible effects • Precise cellular action unknown but acts similar to alkylating agents • Inhibits glycolysis  cellular death • Primary tissue irritant • DNA, RNA, & protein damage • Mutagenic, carcinogenic, teratogenic • Poorly soluble in water; dissolves readily in skin oils • Predilection for moist areas of body • (eyes > resp tract > scrotum > face > anus)

34. Mustard: Clinical Effects • Ocular • Corneal ulceration, iritis, blindness • Respiratory • URT irritation, chemical pneumonitis respiratory failure, death • GI • N &V • Hematologic • Bone marrow suppression, pancytopenia • CVS • CV collapse, shock, death • Immune system • Immunosupression, sepsis • Dermal • Cutaneous burns

35. Mustard: Treatment • Decontamination • Prior to entry into medical facility • Protect workers • Remove all clothing (contaminated) • 0.5% hypochlorite (bleach) irrigation • Debride & decontaminate bullae • US Military kits: • 2 sets of paper towels soaked with phenol & hydroxide followed by chloramine • Adsorbents (flour, talcum powder) • Water less ideal b/c poor solubility but may use in large amounts if nothing else available • Ocular exposures should be rinsed w/ 2.5% thiosulfate sol’n & then topical abx, & cycloplegics  optho consult

36. Mustard: Treatment • No antidote; Tx is supportive • Bronchodilators, O2, steroids, bronchoscopy, mechanical ventilation • Analgesia • Tx cutaneous injuries like burns • Most pts recover completely • Factors associated w/ poor prognosis • Erythema >50% BSA • Dyspnea w/in 4-6 hrs of exposure • Respiratory failure • Bone marrow suppression

37. Mustard Burns

38. Mustard as a terror weapon • Difficult to detect, delayed onset • Potent, w/ significant morbidity • Easy to make, store, transport, & deliver • Bombs, aerosol, vapour, rockets, canisters • 9 openly documented manufacturing methods that can be done with high school lab supplies in someone's basement (the MDA of terrorism if you will) • Cheap • Persistent; difficult to clean up • Sig. experience in mid-east due to use in Iran-Iraq war

39. Halogenated Oximes • Phosgene oxime (CX, dichloroform oxime) • Also known as urticariants or nettle gases • Fair water solubility • Immediate Sx onset; unpleasant odor • No confirmed battlefield use • Penetrates clothing, rubber, & skin rapidly (sec’s) • Enhances penetration of other agents • 2 proposed MOA’s • Direct injury due to corrosive effect & enzyme inhibition • Indirect injury due to alveolar macrophage activation & secondary pulmonary injury (delayed)

40. CX: Clinical effects • Immediate effects & absorption • Mild irritation  severe pain • Skin has grayish blanched appearance & surrounding erythema which can go on to blister or form hives & pruritus • Turns brown & into dark eschar over 24h – 1 wk • Also immediate conjunctivitis & ocular pain

41. CX: Treatment • No antidote • Decontaminate & Supportive Care • US military • M291 decontamination kits • Flush w/ large amounts of water

42. Improvised Agents • Military & terrorist mission goals differ • Many chemical deemed poor for warfare more than appropriate for terror attacks • Thousands of commercial compounds can potentially become weapons • E.g. 911 – jetliners turned into bombs • CDC threat list • 11 categories of diverse potential biological & chemical weapons • Underscores need for generalized approach & disaster planning

43. General Guidelines • Prehospital decontamination ideal • Assume decontamination has NOT occurred • Protective clothing • No PPC suit can protect against all agents, but Level A suits are best • Latex gloves useless; nitrile much better

44. Part III: Radiation Injury

45. Quiz • How large were the atomic (fission) bombs dropped on Hiroshima & Nagasaki? • Equivalent to 12,500 & 20,000 tons of TNT respectively • 66, 000 people instantly died & 69,000 injured in Hiroshima • Blast radius was 3 miles in diameter • What are modern (fusion) thermonuclear warhead yields? • In the mega ton range (largest ever detonated 100 MT) • What was is the lethal radius of a 10 KT weapon? A 20 MT weapon? • 3 miles vs. 35 miles • How many nuclear devices have been detonated? • A: > 2000 tests, >500 above ground • How many nuclear warheads were held at the height of the Cold War? • Over 69,000 in 1985 • How many now? • 32, 000 = > 10,000 MT TNT

46. Basics • Ionizing radiation • Short wavelength, high frequency • High energy: 1 billion x that of non-ionizing • UV, X, & γ rays; α & β particles; neutrons • Released by unstable atomic particle decay = radioactivity • Ability to knock electrons out of orbit of other atoms (ionize them)

47. Ionizing Radiation

48. Units • SI Units • Sievert (Sv) = exposed dose or dose equivalent • 1 Sv = 1 Gy • Gray (Gy) = absorbed dose • 1 Gy = 1 joule energy absorbed / Kg tissue • Becquerel (Bq) = activity • Older Units • Rem = radiation equivalent man • 1 rem = 0.01 Gy • Rad = radiation absorbed dose • 1 rad = 0.01 Sv • Roentgen (R) = exposure • 1 R = 0.01 Gy • Curie (Ci) = activity • 1 Bq = 27 pCi

49. Real Life Examples • 1 CXR = 0.02 mSv • Background radiation ~3 mSv / yr (150 CXR’s) • AXR 1.5 mSv (75 CXR’s) • Abdominal CT 6 – 8 mSv (300-400 CXR’s) • Background radiation in affected parts of Belarus, Ukraine, & Russia 6 -11 mSv / yr (300 – 550 CXR’s) • Firefighters in Chernobyl 0.7 – 13 Sv (35,000 – 650,000 CXR’s)

50. Types of exposure • External radiation • E.g. X-rays • Only neutrons can produce radioactivity • I.e. a pt exposed to other radiation is NOT radioactive & poses no risk to others • External contamination • E.g. radioactive spill in lab • Incorporation & internal contamination • Ingestion, inhalation, open wounds