Hazardous Material Medical Care Corrosives and Oxidizing Agents Methemoglobin forming agents

1. Hazardous Material Medical CareCorrosives and Oxidizing AgentsMethemoglobin forming agents น.พ. สัมมน โฉมฉาย สาขาพิษวิทยาคลินิค อาชีวเวชศาสตร์ และ เวชศาสตร์สิ่งแวดล้อม ภาควิชาเวชศาสตร์ป้องกันและสังคม คณะแพทยศาสตร์ศิริราชพยาบาล มหาวิทยาลัย มหิดล toxbuster@hotmail.com

2. Outline: • Corrosives & Oxidizing agents • Phosphorus • Corrosives with systemic effects • Hydrofluoric acid • Phenol and related agents • Methemoglobinemia Corrosives, Oxidizing & MetHb forming Agents

3. Corrosive • Corrosives: Any chemical with corrosive effects and can cause chemical burns • Acids • Bases • Oxidizers • white phosphorus Corrosives, Oxidizing & MetHb forming Agents

4. Acid, Base and Oxidizing Agents • Arrhenious system, following a swedish chemist • Acid: A substance that dissolves and ionizes in water to produce hydrogen ion, H+ • Base: A substance that dissolves and ionizes in water to produce hydroxide ion, OH- • Oxidizing agents: A substance that reacts with other substances by taking an electrons. Corrosives, Oxidizing & MetHb forming Agents

5. Common industrial and house bases • Sodium and potassium hydroxide: cleaning • Calcium hydroxide: concrete • Lithium hydroxide: photographic industry • Ammonium hydroxide: fertilizers • Ammonium compounds: glass, tub, tile cleaner • Sodium hypochlorite: bleach Corrosives, Oxidizing & MetHb forming Agents

6. Common industrial and house acids • Hydrochloric and sulfuric acid: cleaning • Hydroflouoric acid: glass and metal cleaning • Phosphoric acid: Fertilizers, detergents • Acetic acid: Polymer, rayon, plastic and rubber production • Chromic acid: metal plating • Formic acid: leather tanning, rust remover • Sulfuric acid: automobile batteries Corrosives, Oxidizing & MetHb forming Agents

7. Common oxidizing agents • Chlorine dioxide: Bleaching, water treatment • Hydrogen peroxide: rocket fuel, bleaching food, denture cleaner • Sodium chlorate: Dye production, leather tanning Corrosives, Oxidizing & MetHb forming Agents

8. Alkali burns • Contact with tissue: ‘Liquefaction necrosis’ • Protein dissolution • Collagen destruction • Fat saponification • Penetration of alkali until the excess OH- are consumed • Heat generation from reaction with tissue • Determinants: Strength of alkali (pKa 14 or more is strong), concentration Corrosives, Oxidizing & MetHb forming Agents

9. Acid burns • Protein denaturation and precipitation • Eschar formation • Most acid burns are limited to superficial layer • Determinants: • pH less than 2.5 • volume of acid solution Corrosives, Oxidizing & MetHb forming Agents

10. Oxidizing agent injury • Oxidizing agents react quickly with tissue • Oxidation of tissue • Free oxygen radical production • Heat production Corrosives, Oxidizing & MetHb forming Agents

11. Exposure to corrosives • Inhalation: • The commonest route of exposure • Fume of concentrated acid or base • Aerosols of sprayed acid or base • Skin or mucous membranes:The second commonest route of exposure • Ingestion Corrosives, Oxidizing & MetHb forming Agents

12. Corrosive injury: clinical manifestations • With skin and mucosal exposure, respiratory involvement should always be considered. • Skin: pain, reddening and inflammation, swelling Corrosives, Oxidizing & MetHb forming Agents

13. Ingestion: • Oropharyngeal pain, dysphagia, throat and chest pain, abdominal pain • Absence of oral lesion does not preclude esophageal and gastric lesion • Upper airway obstruction, respiratory distress • GI tract performation Corrosives, Oxidizing & MetHb forming Agents

14. Systemic effects after ingestion • Alkali only cause local contact injury. • acid absorption with acute metabolic acidosis • Anion gap: sulfuric acid • Non-anion gap: hydrochloric acid • Oxidizing agents may be absorbed and cause methemoglobinemia Corrosives, Oxidizing & MetHb forming Agents

15. Corrosive Ingestion: treatment • Airway management • Decontamination • Gastric lavage and induction of emesis is contraindicated: • Repeated corrosive exposure • Perforation risks • Activated charcoal is relatively contraindicated • No proven benefit • Worsen endoscopic visibility Corrosives, Oxidizing & MetHb forming Agents

16. Dilution may be done with drinking 1 cup (250 mL) of water or milk in patients • Ingestion within 30 minutes • No vomiting • No signs of perforation • Neutralization is contraindicated Corrosives, Oxidizing & MetHb forming Agents

17. Endoscopy: • Flexible fiberoptic endoscopy • Indicated in all intentional patients and symptomatic patients • Determine: Location and severity of the injury • Treatment plans and prognosis • A delay of 4-6 hours after ingestion to prevent underestimation of the lesion • Perform no later than 24 hours after the ingestion to minimize risk of perforation Corrosives, Oxidizing & MetHb forming Agents

18. Corrosive skin burn: Management • Thorough decontamination with water or saline • Alkali burns may need longer irrigation and soft soap • Chemical blisters should be broken and irrigated because corrosive substances may be collected within the blister Corrosives, Oxidizing & MetHb forming Agents

19. Ocular corrosive injury: Management • Irrigate affected eye with large amount of water or saline • Nitrazine (pH) paper checked • Irrigate until pH 7.5-8 • Complete ophthalmologic examination after the irrigation Corrosives, Oxidizing & MetHb forming Agents

20. Yellow or white phosphorus • Colorless or yellow wax-like crystalline solid • Garlic-like odor • Insoluble in water • Industries: • Fireworks • Fertilizers Corrosives, Oxidizing & MetHb forming Agents

21. Phosphorus: Skin exposure • Spontaneous combustion when exposed to oxygen in air • Releases phosphorus oxide: • Upper and lower respiratory system irritation • Non-cardiogenic pulmonary edema • Severe skin burns Corrosives, Oxidizing & MetHb forming Agents

22. Phosphorus: Ingestion • Severe GI tract burns • fluid and electrolyte loss & shock • Hyperphosphatemia and hypocalcemia • Tetany • QT-interval prolongation and cardiac arrhythmias • Diarrhea with smoking stool • Acute hepatitis and renal failure on day 2-3 Corrosives, Oxidizing & MetHb forming Agents

23. Phosphorus: Treatment • Decontamination • If solid embedded in tissue: keep the area submerged in water before surgical debridement • Identification of embedded phosphorus is often difficult • Paint with 1-3% copper sulfate solution: blue solids of copper phosphide • Removed phosphorus placed under water Corrosives, Oxidizing & MetHb forming Agents

24. Fluid replacement • Calcium replacement for hypocalcemia Corrosives, Oxidizing & MetHb forming Agents

25. Corrosives with systemic involvement • Hydrogen fluoride • Phenol Corrosives, Oxidizing & MetHb forming Agents

26. Hydrofluoric acid • An acid with industrial and household applications • Glass and ceramic • Cleaning sand stone and marble • Semiconductor • Exposure • Topical skin and mucosal exposure • inhalation of fume • Ingestion Corrosives, Oxidizing & MetHb forming Agents

27. Hydrofluoric acid • Ionize after penetration into tissue • H+ release like other acids • F- ion binds calcium and magnesium • Insoluble calcium fluoride and magnesium salt in tissue • Deplete intracellular calcium and magnesium Corrosives, Oxidizing & MetHb forming Agents

28. Hydrofluoric acid: skin exposure • Household agents: • concentration less than 20% may not result in immediate pain and delay up to 24 hours • concentration 20-50 % may not result in immediate pain and delay up to 8 hours • Concentration >50% causes immediate pain and rapid onset of hypocalcemia Corrosives, Oxidizing & MetHb forming Agents

29. Tissue burns may progress gradually over a week • Facial exposure may be very susceptible for systemic toxicity • Lesion starts with mild erythematous area that progresses to second or third degree burns in low concentration • Immediate pale and blanched area with surrounding erythema for high concentration Corrosives, Oxidizing & MetHb forming Agents

30. Commonly exposed area is hand. • Nail involvement • needs aggressive management • nail bed necrosis and distal phalanx demineralization Corrosives, Oxidizing & MetHb forming Agents

31. Hydrofluoric acid: Ingestion • Severe pain in mouth and throat, esophagus • Inflammation, necrosis and perforation of esophagus • Gastrointestinal hemorrhage • Systemic toxicity usually occur after GI symptoms • Onset of systemic toxicity within 6 hours (mostly within 1 hour) Corrosives, Oxidizing & MetHb forming Agents

32. Hydrofluoric acid: inhalation • Industrial setting: HF concentration of 50% or more • Indicators for suspicion • Burn with > 50% BSA • Burn in head and neck • Confined space burn • Delayed removal of soaked clothing • Upper and lower respiratory irritation • Possible systemic toxicity Corrosives, Oxidizing & MetHb forming Agents

33. Hydrofluoric acid: ocular injury • The eye is very sensitive to HF fume in the air: severe irritation • Severe conjunctival injection and chemosis • Keratitis and corneal opacity • These pathology may be delayed for up to 24 hours Corrosives, Oxidizing & MetHb forming Agents

34. Hydrofluoric acid: systemic toxicity • Hypocalcemia • Muscle weakness and tetany • Fatigue • Prolonged QT interval • Refractory torsade de pointes and ventricular fibrillation • Seizures and alteration of consciousness Corrosives, Oxidizing & MetHb forming Agents

35. Hydrofluoric acid skin burn: management • Decontaminate with large amount of water (at least 20 minutes) • Patients with burn should be treated with topical calcium gluconate therapy • Cover burned areas with 2.5% calcium gluconate gel • Gel may be applied using surgical glove • Pain should be relieved within 45 minutes • Change gel when pain recurs or every 4 hours • In small, severe burns, surgical debridement may facilitate topical treatment Corrosives, Oxidizing & MetHb forming Agents

36. Preparation of calcium gluconate gel • Mix 10 ml of 10% calcium gluconate in 60 mL of KY gel • Mix 10 tablets of 10 g calcium carbonate (crushed) in 60 mL of KY gel Corrosives, Oxidizing & MetHb forming Agents

37. Tissue infiltration • Indications • 1. Failure to respond to 30 minutes of topical treatment • 2. Severe burns • 5% calcium gluconate not more than 0.5 mL per cm2 • Gauge 27 or 30 needle • Normal tissue 0.5 cm away from necrotic margin • Calcium chloride should not be used Corrosives, Oxidizing & MetHb forming Agents

38. Recurrence or persistence of pain indicates on-going tissue damage • and more aggressive treatment is indicated • Limitations of tissue infiltration • 1. Pain due to calcium • 2. Nail involvement needs nail extraction Corrosives, Oxidizing & MetHb forming Agents

39. Intravenous regional infusion ‘Bier Block technique’ • Indicated if tissue infiltration is ineffective • 1. An IV cannula place on dorsum of affected hand • 2. Elevated the extremity for 5 minutes • 3. Apply pneumatic cuff tourniquet just proximal to the elbow • 4. Apply pressure to 100 mmHg above systolic BP • 5. 10 ml of 10% calcium gluconate in 30 mL of D5W is infused into the cannula • 6. Release tourniquet at 25 minutes by gradually decrease cuff pressure over 3-5 minutes Corrosives, Oxidizing & MetHb forming Agents

40. Muscle cramping may develop • Diazepam 5-10 mg IV • Repeat the treatment if pain recurs Corrosives, Oxidizing & MetHb forming Agents

41. Hydrofluoric acid ocular burn: management • Irrigation with water or saline, if available Lactated Ringer’s solution is preferable. • Irrigate with calcium gluconate solution: 10% calcium gluconate solution 50 ml in normal saline 500 ml • Apply 1% calcium gluconate as eye drops every 2-3 hours Corrosives, Oxidizing & MetHb forming Agents

42. Hydrofluoric acid: management • Monitor Calcium level hourly in first 6 hours • Monitor ECG • Patients should be monitored for at least 24 hours Corrosives, Oxidizing & MetHb forming Agents

43. Hydrofluoric acid: Treatment of systemic toxicity • Prolonged QT syndrome • 10 ml of 10% calcium gluconate over 5 minutes (bolus if in emergency) • 20 mL of 20% magnesium over 20 minutes Corrosives, Oxidizing & MetHb forming Agents

44. Phenol • White crystalline, pink, red • Exposure • Disinfectant • Pharmaceuticals • Lab. Reagent • Wood preservatives Corrosives, Oxidizing & MetHb forming Agents

45. Low concentration (5%) can kill • Well absorbed through skin and mucosa • Skin burn: white layer of precipitated protein (keratocagulation) • Ingestion: GI irritation, nausea & vomiting Corrosives, Oxidizing & MetHb forming Agents

46. Systemic effects onset of 15-60 minutes: • excitation • CNS depression • hypotension: vasodilation and negative inotropic effects • respiratory depression • convulsion Corrosives, Oxidizing & MetHb forming Agents

47. Phenol: Management • Removal of soaked cloth • Initial decontamination with dry decontamination and large amount of water ASAP • Then: further decontamination • If skin area less than 5% BSA use 70% isopropyl alcohol or polyethylene glycol • If skin area larger than 5% BSA use polyethylene glycol (Colyte) or olive oil, mineral oil, vegetable oil Corrosives, Oxidizing & MetHb forming Agents

48. For ingestion: • Gastric lavage if present within 1 hours • Activated charcoal if presented after 1 hour • Supportive and symptomatic care • Observe for 6 hours for asymptomatic patients Corrosives, Oxidizing & MetHb forming Agents

49. Methemoglobinemia • Hemoglobin binding to oxygen needed heme iron in ferrous state (Fe2+) • Methemoglobinemia • Oxidized Hb (1 electron taken) • Heme iron in ferric state (Fe3+) • Do not bind oxygen & impaired oxygen release to tissue • In normal human body less than 1% metHb: maintained by reduction system Corrosives, Oxidizing & MetHb forming Agents

50. Methemoglobin reduction system • Regular pathway in human body • High energy compound (NADH) from glycolysis • NADH reduces (donates 1 electron) cytochrome B5 • Reduced cytochrome B5 reduces MetHb to Hb2+ Corrosives, Oxidizing & MetHb forming Agents