32.1

Chemical Injuries

Chapter 32

Chemical Injuries

The reader is strongly advised to supplement material

in this chapter with the Medical Management Of

Chemical Casualties Handbook, 3rd ed., 2000,

USAMRICD, Aberdeen Proving Ground, MD.

Personal Protection

 Prevention!

ο Avoid becoming a casualty.

ο Protect yourself and instruct your personnel to do the

same.

 Prevent further injury of the casualty by instructing him to

put on the protective mask and mission-oriented protective

posture (MOPP) ensemble, and administer self-aid. If

contaminated, tell the individual to remove clothing and

decontaminate potentially exposed body surfaces.

 Provide buddy aid by masking the individual, administering

antidotes, and spot decontaminating exposed body areas.

 Ensure completeness of decontamination process to the

greatest extent possible at the collocated patient decontamination station.

ο Potential for vapor exposure from an off-gassing residual

agent or inadvertent contact with undetected liquid is a

hazard for medical personnel.

ο Avoid contamination of the medical treatment facility (MTF).

Initial Treatment Priorities

 There is no single “best” way to prioritize emergency

treatment for chemical or mixed casualties, although

respiratory insufficiency and circulatory shock should be

treated first. One workable sequence is shown below.
32.2

Emergency War Surgery

1. Treat respiratory insufficiency (airway management)

and control massive hemorrhage.

2. Administer chemical agent antidotes.

3. Decontaminate the face (and protective mask if donned).

4. Remove contaminated clothing and decontaminate

potentially contaminated skin.

5. Render emergency care for shock, wounds, and open

fractures.

6. Administer supportive medical care as resources permit.

7. Transport the stabilized patient to a contaminationfree (ie, clean) area.

Specific Chemical Warfare (CW) Agents and Treatment

Considerations

Nerve Agents (GA, GB, GD, GF and VX)

 General: Nerve agents are among the most toxic of the known

chemical agents. They pose a hazard in both vapor and liquid

states, and can cause death in minutes by respiratory

obstruction and cardiac failure.

 Mechanism of action: Nerve agents are organophosphates

that bind with available acetylcholinesterase, permitting a

paralyzing accumulation of acetylcholine at the myoneural

junction.

 Signs/symptoms: Miosis, rhinorrhea, difficulty breathing,

loss of consciousness, apnea, seizures, paralysis, and copious

secretions.

 Treatment: Each deployed US service member has three

MARK I kits or Antidote Treatment-Nerve Agent Autoinjectors

(ATNAAs) for IM self-injection in a pocket of the protective

mask carrier; each kit delivers 2 mg injections of atropine

sulfate and 600 mg pralidoxime chloride (2-PAMCl). Each

US service member also carries a 10 mg diazepam autoinjector

to be administered by a buddy.

ο Immediate IM or IV injection with

♦ Atropine to block muscarinic cholinergic receptors (may

require multiple doses in much greater amounts than

recommended by Advanced Cardiac Life Support

[ACLS] doses).
32.3

Chemical Injuries

♦ 2-PAM (if given soon after exposure) to reactivate

cholinesterase.

 Pretreatment: Military personnel may have also received

pretreatment prior to nerve agent exposure. In the late 1990s,

the US military fielded pyridostigmine bromide (PB tablets)

as a pretreatment for nerve agent exposure (this reversibly

binds to the enzyme acetyl cholinesterase, enhancing the

efficacy of atropine against Soman).

Vesicants (HD, H, HN, L, and CX)

 General: The vesicants (blister agents) are cytotoxic alkylating

compounds, exemplified by the mixture of compounds

collectively known as “mustard.” Sulphur mustard is

designated “HD” or “H”; nitrogen mustard is designated as

“HN”; Lewisite is designated as “L”; and phosgene oxime is

designated as “CX”.

 Mechanism of action: Mustard is an alkylating agent that

denatures DNA, producing a radiomimetic effect, produces

liquefaction necrosis of the epidermis, severe conjunctivitis,

and if inhaled, injures the laryngeal and tracheobronchial

mucosa.

 Signs/symptoms: Skin blisters, moderate-to-severe airway

injury (presentation can be delayed), conjunctivitis of varying

severity that causes the casualty to believe he has been

blinded, and mucus membrane burns. No delay with

Lewisite: immediate burning of the skin and eyes.

 Treatment: Preventive and supportive. Immediate

decontamination of the casualty has top priority. Agent

droplets should be removed as expeditiously as possible

by blotting with the M-291 kit, or flushing with water or

0.5% hypochlorite. The M-291 kit is extremely effective at

inactivating mustard. Most military forces carry a

decontamination powder or liquid that should be used

immediately to remove the vesicant. Because mustard

tends to be an oily solution, water may spread the agent.

Dimercaprol is used by some nations in the treatment of

Lewisite. Dimercaprol must be used with caution because

the drug itself may be toxic.
32.4

Emergency War Surgery

Lung Damaging (Choking) Agents (Phosgene [CG],

Diphosgene [DP], Chloropicrin [PS], and Chlorine)

 General: Lung damaging or choking agents produce

pronounced irritation of the upper and the lower respiratory

tracts. Phosgene smells like freshly mowed hay or grass.

 Mechanism of action: Phosgene is absorbed almost exclusively

by inhalation. Most of the agent is not systemically distributed

but rather is consumed by reactions occurring at the alveolarcapillary membrane.

 Signs/symptoms: Phosgene exposure results in pulmonary

edema following a clinically latent period that varies,

depending on the intensity of exposure. Immediate eye, nose,

and throat irritations may be the first symptoms evident after

exposure (choking, coughing, tightness in the chest, and

lacrimation). Over the next 2–24 hours the patient may

develop noncardiogenic fatal pulmonary edema.

 Treatment:

ο Terminate exposure, force rest, manage airway secretions,

O2, consider steroids.

ο Triage considerations for patients seen within 12 hours after

exposure.

♦ Immediate care in ICU if available for patients in

pulmonary edema.

♦ Delayed: dyspnea without objective signs of pulmonary

edema, reassess hourly.

♦ Minimal: asymptomatic patient with known exposure.

♦ Expectant: patient presents with cyanosis, pulmonary

edema, and hypotension. Patients presenting with these

symptoms within 6 hours of exposure will not likely survive.

The Cyanogens (Blood Agents AC and CK)

 General: Hydrogen cyanide (AC) and cyanogen chloride

(CK) form highly stable complexes with metalloporphyrins

such as cytochrome oxidase. The term “blood agent” is an

antiquated term used at a time when it was not understood

that the effect occurs mostly outside the bloodstream.

 Mechanism of action: Cyanide acts by combining with

cytochrome oxidase, blocking the electron transport system.

As a result, aerobic cellular metabolism comes to a halt.
32.5

Chemical Injuries

 Signs/symptoms: Seizures, cardiac arrest, and respiratory arrest.

 Treatment:

ο Immediate removal of casualties from contaminated

atmosphere prevents further inhalation.

ο 100% oxygen.

ο If cyanide was ingested, perform GI lavage and administer

activated charcoal. Administer sodium nitrite (10 mL of

3% solution IV) over a period of 3 minutes, followed by

sodium thiosulfate (50 mL of 25% solution IV) over a 10-

minute period. The sodium nitrite produces methemoglobin that attracts the cyanide; the sodium thiosulfate

solution combines with the cyanide to form thiocyanate,

which is excreted.

Incapacitation Agents (BZ and Indoles)

 General: Heterogeneous group of chemical agents related to

atropine, scopolamine, and hyoscyamine that produces

temporary disabling conditions with potent CNS effects that

seriously impair normal function, but do not endanger life

or cause permanent tissue damage.

 Signs/symptoms: Mydriasis, dry mouth, dry skin, increased

reflexes, hallucinations, and impaired memory.

 Treatment:

ο Immediate removal of firearms and other weapons to

ensure safety.

ο Close observation.

ο Physostigmine, 2–3 mg IM every 15 minutes to 1 hour until

desired level is attained; maintain with 2–4 mg IV every

1–2 hours for severe cases.

Thickened Agents

 Thickened agents are chemical agents that have been mixed

with another substance to increase their persistency (persistent

agents may remain in the environment over 24 h).

 Casualties with thickened nerve agents in wounds are

unlikely to survive to reach surgery.

 Thickened mustard has delayed systemic toxicity and can

persist in wounds, even when large fragments of cloth have

been removed.
32.6

Emergency War Surgery

Surgical Treatment of Chemical Casualties

 Wound decontamination.

The initial management of a casualty contaminated by chemical

agents will require removal of MOPP gear as well as initial skin

and wound decontamination with 0.5% hypochlorite before

treatment.

ο Bandages are removed, wounds are flushed, and bandages

replaced.

ο Tourniquets are replaced with clean tourniquets after

decontamination.

ο Splints are thoroughly decontaminated.

Only the vesicants and nerve agents present a hazard from

wound contamination. Cyanogens are so volatile that it is

extremely unlikely they would remain in a wound.

Off-Gassing

 The risk of vapor off-gassing from chemically contaminated

fragments and cloth in wounds is very low and insignificant.

Off-gassing from a wound during surgical exploration will

be negligible or zero.

Use of Hypochlorite Solution

 Household bleach is 5% sodium hypochlorite, hence, mix 1

part bleach with 9 parts water to create ~ 0.5% solution.

 Dilute hypochlorite (0.5%) is an effective skin decontaminant,

but the solution is contraindicated for use in or on a number

of anatomical areas:

ο Eye: may cause corneal injuries.

ο Brain and spinal cord injuries.

ο Peritoneal cavity: may lead to adhesions.

ο Thoracic cavity: hazard is still unknown although it may

be less of a problem.

 Full strength 5% hypochlorite is used to decontaminate

instruments, clothing, sheets, and other inanimate objects.

Wound Exploration and Debridement

Surgeons and assistants should wear well-fitting, thin, butyl

rubber gloves or double latex surgical gloves. Gloves should
32.7

Chemical Injuries

be changed often while ascertaining that there are no foreign

bodies or thickened agents remaining in the wound.

Wound excision and debridement should be conducted using a

no-touch technique. Removed fragments of tissue should be

dumped into a container of 5% hypochlorite solution. Superficial

wounds should be wiped thoroughly with a 0.5% hypochlorite

and then irrigated with copious amounts of normal saline.

Following the Surgical Procedure

 Surgical and other instruments that come into contact with

possible contamination should be placed in 5% hypochlorite

for 10 minutes prior to normal cleansing and sterilization.

 Reusable linen should be checked with the chemical agent

monitor (CAM), M8 paper, or M9 tape for contamination.

Soak contaminated linen in 5% hypochlorite.
32.8

Emergency War Surgery