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.
Avoid becoming a casualty.
Protect yourself and instruct your personnel to do the same.
Potential for vapor exposure from an off-gassing residual agent or inadvertent contact with undetected liquid is a hazard for medical personnel.
Avoid contamination of the medical treatment facility (MTF).
Initial Treatment Priorities
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.
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).
2-PAM (if given soon after exposure) to reactivate cholinesterase.
Vesicants (HD, H, HN, L, and CX)
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 alveolar-capillary 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.
Terminate exposure, force rest, manage airway secretions, O2, consider steroids.
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.
Immediate removal of casualties from contaminated atmosphere prevents further inhalation.
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)
Immediate removal of firearms and other weapons to ensure safety.
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.
Surgical Treatment of Chemical Casualties
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.
Bandages are removed, wounds are flushed, and bandages replaced.
Tourniquets are replaced with clean tourniquets after decontamination.
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.
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:
Eye: may cause corneal injuries.
Brain and spinal cord injuries.
Peritoneal cavity: may lead to adhesions.
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 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