Hazmat, Emergency Medicine

Basics

Description

Hazmat refers to exposure to hazardous materials causing local or systemic toxicity.
Pathophysiology:
- Acids cause coagulation necrosis with eschar, usually limiting penetration to deeper tissue.
- Alkalis cause liquefaction necrosis and soluble complexes that penetrate into deep tissues.
- Damage also occurs through oxidation, protein denaturation, cellular dehydration, local ischemia, and by metabolic competition/inhibition.

Etiology

Hazardous materials are encountered in household, industry, agriculture, transportation accidents, and in criminal/terrorist activities.
The toxicity of the materials relates to the particular substances and their effects.

Diagnosis

Signs and Symptoms

Skin:
- Chemical burns; may appear deceptively mild initially
- Visible liquid or powder on skin
- Absorption through skin may cause systemic toxicity.
Mucous membranes (eyes, nasopharynx; see Corneal Burn):
- Ranges from subjective irritation to serious mucosal burns
- Potential airway compromise
Pulmonary:
- Cough
- Pleuritic chest pain
- Bronchospasm
- Dyspnea
- Pulmonary edema (immediate or delayed)
Systemic (after skin or pulmonary absorption):
- Altered mental status
- Seizures
- Tachy/brady dysrhythmias
- Hypotension/HTN
- GI symptoms
- Electrolyte disturbances
- Carboxyhemoglobinemias and methemoglobinemias
- Cyanide toxicity
- Cholinergic syndrome (see Chemical Weapons Poisoning, Nerve Agents)

History
Elicit type, circumstances, and duration of exposure �

Essential Workup

Attempt to identify substance using pre-hospital providers, Material Safety Data Sheet (MSDS), and Chemical Transportation Emergency Center (Chemtrec).
MSDS:
- Identifies chemicals
- Differentiates vapor vs. skin hazard
- Determines need for decontamination
- Limited treatment data
Determine route and duration of exposure.
Inhalation injury more likely in an enclosed space
Determine toxicity using poison control; computerized databases, such as POISINDEX or TOXNET; or standard toxicology test.
Observe as needed for systemic toxicity.

Diagnosis Tests & Interpretation

Lab

Depends on substance
Electrolytes, BUN, creatinine, and glucose levels
LFTs
Calcium level
Magnesium level
Phosphorus level
Arterial blood gases:
- Metabolic acidosis
- Carboxyhemoglobinemias and methemoglobinemias
- Respiratory failure

Imaging
Chest radiograph for pulmonary edema �

Differential Diagnosis

Skin:
- Hypersensitivity reaction
- Thermal burns
Pulmonary:
- Pneumonia
- Pulmonary embolism
- Anaphylaxis
Systemic:
- Status epilepticus
- Overdose
- Psychiatric illness
- Myocardial infarction

Treatment

Pre-Hospital

Recognize a HAZMAT situation:
- Accident at industrial/agricultural site
- Accident involving transport of hazardous materials
- Suspected terrorist mass casualty incident
- Cholinergic syndrome
- Irritant mucous membrane symptoms
- Chemical burns
Protect yourself:
- Approach from upwind.
- Do not enter scene until safety of material is determined.
- Use Level A protective gear if safety not established
- Anyone able to walk and talk is minimally contaminated.
Personal chemical protective equipment:
- Level A: Positive-pressure self-contained breathing apparatus (SCBA), fully encapsulated chemical-resistant suit, double chemical-resistant gloves, chemical-resistant boots, and airtight seals between suit, gloves, boots
- Level B: SCBA, nonencapsulated chemical suit, double gloves, boots
- Level C: Air-purification device, suit, gloves, boots
- Level D: Common work clothes
- Identify substance:
  - Department of Transportation (DOT) placard, MSDS, shipping papers, hazard labels
  - If unsuccessful, call Chemtrec (1[800] 424-9300) to determine substance and toxicity.
  - Hazmat teams can do chemical testing.
Determine toxicity and need for decontamination:
- Poison control (1[800] 222-1222)
- Chemtrec
Decontaminate:
- Hazmat team
Treat:
- Provide basic life support and advanced life support care as indicated.
- Generally basic list support only in a "hot zone"�
- Irrigate skin and ocular burns immediately and continue until arrival at hospital.

Initial Stabilization/Therapy

Protect ED personnel:
- Secondary contamination can occur from dermal contact or through inhalation of volatile gases/particles.
Keep patients outside in designated hot zones until decontaminated.
When in doubt, decontaminate.
Expect contaminated patients to arrive via emergency medical services or private vehicle.
If treatment is required before/during decontamination:
- Use minimum necessary staff in appropriate personal protection gear.
- Focus on life- and limb-saving care only.
Decontamination:
- Security to enforce hot zone
- Remove, label, and double-bag clothing (including contact lens).
- Copious irrigation with soap and water for 10-15 min with special attention to obviously contaminated areas, wounds, and exposed eyes
- Recapture water to prevent contamination of the sewer and downstream areas:
  - In an emergency or mass casualty situation, it is acceptable to let water drain into sewer.
- Hydrotherapy:
  - Mainstay of therapy for chemical burns
  - Contraindicated only for elemental metals (sodium and potassium)
- Allow patient to decontaminate himself or herself or use trained decontamination team.
- Decontaminate children, dependent elderly, mentally/physically challenged and their appliances (e.g., wheelchairs) with caregivers
- Gloves, masks, goggles, and disposable gowns provide some protection
- Remove/replace bandages, tourniquets, airway adjuncts, IV sets
- Retriage after decontamination.

Ed Treatment/Procedures

Provide supportive care as needed.
Determine if antidotal treatment would be effective and available.
Hazmat incidents provoke extreme fear:
- Expect casualties suffering from collective hysteria.
- Knowledge of toxicologic profile can exclude contamination in these patients.
ED staff may become symptomatic even if chemical concentrations in the air are below toxic levels and may need to be escorted to fresh air.
Chemical burns:
- Irrigation should be started as soon as possible and, if owing to a strong alkali, may need to be continued for hours.
- Aggressive fluid resuscitation with 2-4 mL/kg lactated Ringer solution per total burn surface area (TBSA) percent over 24 hr with 1/2 given over the 1st 8 hr
- Pain control
Pulmonary symptoms:
- Bronchodilators, oxygen, intubation, and mechanical ventilation
Selected special treatments:
- Hydrofluoric acid burns:
  - Calcium gluconate via topical cutaneous gel, SC, or intra-arterial
  - For systemic toxicity: IV calcium gluconate and magnesium
- Phenol burns:
  - Remove phenol from skin with polyethylene glycol 300 or 400 or with isopropyl alcohol.
- Nitrates:
  - Ingested or extensive burns may cause methemoglobinemia.
  - Treat levels >30% with high-flow oxygen and IV methylene blue.
- Elemental metals (sodium/potassium):
  - Water lavage is contraindicated and dangerous.
  - Cover with oil until substance can be d �brided from skin.
- Cyanide toxicity:
  - Hydroxocobalamin administration
- Organophosphates/carbamate insecticides (see Chemical Weapons Poisoning)

Medication

Albuterol: 2.5-5.0 mg nebulized
Calcium gluconate: 10 mL of 10% solution applied topically. Consult poison center for instructions.
Magnesium: 2 g IV over 20 min
Methylene blue: 1-2 mg/kg slow IV (peds: Not recommended for <6 yr old; >6 yr old: 1 mg/kg IV/IM over 5 min)
Hydroxocobalamin: 5 mg IV over 5 min, repeat once

Follow-Up

Disposition

Admission Criteria

Airway compromise, respiratory difficulty (hypoxia)
Significant systemic symptoms
Admit patients with chemical burns to burn center.

Discharge Criteria

Patients who are well after a period of observation and consultation with poison control
Superficial chemical burns owing to a toxin without potential for systemic toxicity (weak acid/alkali)

Followup Recommendations

Psychiatric or social work referral for victims of chemical terrorist attacks. �

Pearls and Pitfalls

Decontaminate stable victims on site when possible.
Protect medical providers (pre-hospital and ED) with appropriate personal protective equipment.
Provide specific antidotes for exposures when indicated.
Victims who can walk and talk are minimally contaminated.

Additional Reading

Clarke �SF, Chilcott �RP, Wilson �JC, et al. Decontamination of multiple casualties who are chemically contaminated: A challenge for acute hospitals. Prehosp Disast Med. 2008;23(2):175-181.
Freyberg �CW, Arquilla �B, Fertel �BS, et al. Disaster preparedness: Hospital decontamination and the pediatric patient-Guidelines for hospitals and emergency planners. Prehosp Disaster Med. 2008;23(2):166-172.
Goldfrank �LR, Flomenbaum �NE, Howland �MA, et al. Goldranks Toxicologic Emergencies. 8th ed. New York, NY: McGraw-Hill; 2006;1764-1774.
Streets �KW, Johnson �DA. Development and Implementation of a Multidisciplinary Emergency Department Hazmat Team. International Nursing Library. 2011; http://hdl.handle.net/10755/162923

Codes

ICD9

V87.09 Contact with and (suspected) exposure to other hazardous metals
V87.2 Contact with and (suspected) exposure to other potentially hazardous chemicals
V87.39 Contact with and (suspected) exposure to other potentially hazardous substances
V87.19 Contact with and (suspected) exposure to other hazardous aromatic compounds

ICD10

Z77.018 Contact with and (suspected) exposure to other hazardous metals
Z77.098 Contact w and expsr to oth hazard, chiefly nonmed, chemicals
Z77.128 Contact with and (suspected) exposure to other hazards in the physical environment
Z77.028 Contact with and (suspected) exposure to other hazardous aromatic compounds
Z77.29 Contact with and (suspected) exposure to other hazardous substances

SNOMED

420239005 exposure to toxin (event)
102435003 Exposure to chemical pollution (event)
418715001 Exposure to potentially harmful entity (event)
418307001 Exposure to biological agent (event)

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