Medical Aspects of Chemical Warfare (2008) - The Black Vault

Medical Aspects of Chemical Warfarethe challenges and risks associated with night operations,leaders should develop night plans to meettheir organizational mission objective and train theirpersonnel accordingly. These plans should then beincorporated into the organization’s tactical standingoperating procedures.DECONTAMINATION IN COLD WEATHERAlthough cold temperatures can decrease the effectivenessof deploying some chemical agents, variouschemical formulations have been developed forcold-weather use, such as Lewisite, which can remaina liquid at freezing temperatures. A more realisticthreat today is the purposeful or accidental release ofhazardous industrial chemicals during cold weather.Accidents of this type regularly occur in the UnitedStates through ground and rail transportation mishaps,such as the January 2005 train derailment in Graniteville,South Carolina, which released chlorine gas. 80 Ona cold day, chemical agents can also be dispersed inwarm areas such as buildings. In the event of a buildingevacuation, casualties might be required to report toan outside assembly area or decontamination station.Additionally, nighttime temperature drops and rainyconditions produce reduced temperature situationseven in warm climates.Cold Shock and HypothermiaCool temperatures greatly increase the risk of coldshock and hypothermia. 81 Cold shock occurs when anindividual is suddenly exposed to cold temperatures,such as cold water in a decontamination shower. 82Cold shock can cause death by triggering peripheralvasoconstriction, a gasp reflex, hyperventilation, andrapid heart rate leading to heart failure. 83 Casualtieswho are medically compromised, elderly, or haveheart disease are particularly at risk. Hypothermia,though less of a threat than cold shock, occurs whenthe body core temperature drops below its normal98.6°F (37°C) range. 82Giesbrecht, who studied hypothermia extensively,identified its symptoms and stages (Table 16-5). 83 Mildhypothermia begins when victims are no longer ableto shiver and their motor responses begin to becomeimpaired. A narrow window of only 7°C (13°F) belownormal core body temperature exists before severehypothermia can develop. A rapid drop in core bodytemperature will occur in patients who are alreadymedically compromised (eg, have symptoms of chemicalagent exposure or coexisting traumatic injuries).Trauma itself causes hypothermia. 84 Those with hypothermiawho are already medically compromisedare at much higher risk of death than those who arenormothermic. 85,86 The use of benzodiazepines (eg,diazepam), the anticonvulsant for exposure to nerveTable 16-5Stages and Symptoms of HypothermiaStage Core Temp Status Symptoms°C °FNormal 35.0–37.0 95.0–98.6 Muscle and mental control and responsesCold sensation; shivering.Mild 32.0–35.0 89.6–95.0 to stimuli fully active.Physical (fine and gross motor) andmental (simple and complex) impairment.Moderate 28.0–32.0 82.4–89.6 Muscle and mental control and responsesto stimuli reduced or cease tofunction.At 86°F (30°C) shivering stops, loss ofconsciousness occurs.Severe < 28.0 < 82.4 Responses absent. Rigidity; vital signs reduced or absent;risk of ventricular fibrillation/cardiacarrest (especially with rough handling).< 25.0 < 77.0 Spontaneous ventricular fibrillation; cardiac arrest.Data sources: (1) Giesbrecht GG. Pre-hospital treatment of hypothermia. Wilderness Environ Med. 2001;12:24-31. (2) US Army Soldier andBiological Chemical Command. Guidelines for Cold Weather Mass Decontamination During a Terrorist Chemical Agent Incident. Revision 1. AberdeenProving Ground, Md: SBCCOM; 2003.548