Emergency War Surgery NATO Handbook: Part I: Types of Wounds and Injuries: Chapter VI: Chemical Injury
Blister Agents
United States Department of Defense
The blister (vesicant) agents are cytotoxic alkylating compounds exemplified by the mixture of compounds collectively known as "mustard" or "mustard gas" (H). Other blister agents are sulfur mustard (HD), nitrogen mustard (HN), phosgene oxime (CX), and Lewisite (L), an arsenical vesicant. Mustard vapor injury is a particular threat in hot climates. High humidity in a hot environment further enhances contact damage to the skin.
Diagnosis: The diagnosis of chemical skin injury is straight forward once blisters have appeared, but early and correct recognition of blister agent exposure can be difficult because:
- Eye inflammation and upper respiratory tract irritation, often the first effects noted, present a picture similar to that produced by choking agents.
- Although dermal damage occurs within minutes of contact, it cannot always be seen immediately and is commonly painless until subdermal layers become involved and blisters form several hours later.
After a 1-12 hour (or more) latent period, during which burning and itching may occur, erythema appears on exposed skin. In dark-skinned casualties, sulfur mustard lesions may turn coal black in such areas as the face, neck, axilla, groin, and genitalia. Erythema is followed by coalescing, translucent, yellowish blisters on a red base. Healing and resorption of non-infected blisters occur in 1-3 weeks. Broken blisters must be protected to minimize chances for infection and subsequent scarring of denuded skin.
Lewisite is differentiated from the mustards by pain immediately upon skin contact. Nasal irritation, sneezing, and pungent odor provide early warning of the presence of Lewisite vapor. Only those without, or incapable of donning the mask will suffer serious respiratory effects.
Treatment: Forward treatment of vesicant injuries is mainly preventive and supportive. Immediate decontamination of the casualty has top priority. Agent droplets should be removed as expeditiously as possible by blotting or flushing. The M-258A1 decon kit is extremely effective in inactivating mustard, but it is also quite caustic. A surgical soap and cool water wash suffices, particularly for widely contaminated skin. Neither scrubbing nor hot water is recommended since both accelerate absorption and increased vapor formation. Army TM 8-285 provides further details regarding proper decontamination procedures.
Eye. Immediately flush the contaminated eye with water. Antibiotic ointment, with or without steroid, helps minimize infection. In more severe cases, blepharospasm and pain are extreme, requiring local anesthetic drops or ointment (e.g., tetracaine). Irrigation with sterile saline will remove crusted exudate.
Respiratory Tract. Inhalation of mustard vapor produces severe irritation of the upper respiratory tract, with painful cough, bloody sputum, chest pain, and dyspnea. Treatment is symptomatic at first, since the severity of the broncho-pulmonary lesion may not become evident for some time. Even asymptomatic patients should be observed for at least 4-6 hours, and not released until after re-examination of the chest. Lewisite vapor produces similar effects, except for more pronounced nasal irritation and sneezing
Tracheitis and bronchitis are prominent; however, fulminant pulmonary edema is much less common with the blister agents than with the choking agents. Bronchopneumonia is a common complication; a change in the appearance of the sputum (culture if possible) is a clear indication for antibiotic therapy.
Prophylactic antibiotic administration is neither necessary nor recommended.
Skin. Doctrinal (TM 8-285) treatment recommends the opening and draining of blisters with removal of the blister fluid. Syringe aspiration of bullous fluid from large blisters might be as effective. Supportive therapy for mustard burns is essentially similar to that for thermal burns: aggressive fluid replacement, pain relief, and vigilance against bacterial infection. From the standpoint of personnel, facilities, and re-supply, forward-positioned medical resources would be severely stressed in the event of widespread utilization of mustard gas by the enemy.
Systemic. Bone marrow depression with severe leukopenia and thrombocytopenia follows extensive mustard absorption. Resistance to infection is diminished, with correspondingly high mortality from pneumonitis or other bacterial infections. Mustard ingested with water or food may damage gastrointestinal epithelium, resulting in blood and fluid losses.
Arsenical vesicants, such as Lewisite, increase capillary permeability, causing extensive third-space fluid shifts. Intravascular hemolysis of erythrocytes, and subsequent hemolytic anemia, complicate the clinical picture and may lead to renal failure. Intramuscular BAL (1 ml per 50 pounds, not to exceed 4 ml) is given at 4 hour intervals for a total of 4 doses. In severe cases, follow-up treatment for 3-4 days with the daily deep IM injections of 1 ml per 100 pounds is recommended.