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

Medical Aspects of Chemical Warfaredent, casualties will probably take at least 15 minutesafter the exposure to reach a medical treatment area.Furthermore, some casualties will not seek medicalattention until effects from the agents are apparent,and an appreciable amount of time may elapse beforethe casualty is seen.Nerve AgentsIn a unit-level MTF, nerve agent casualties might beclassified as immediate, minimal, delayed, or expectant.In a full-care MTF, a nerve agent casualty is unlikely tobe classified as expectant because treatment should beavailable. A nerve agent casualty who is walking andtalking can generally be treated and returned to dutywithin a short period (see Chapter 5, Nerve Agentsfor a more complete discussion of nerve agent effectsand treatment). In most cases, rather than reporting tothe triage point, military personnel exposed to nerveagents should self-administer the Mark I or antidotetreatment nerve agent autoinjector (ATNAA), either ofwhich should reverse the respiratory effects of vaporexposure. Casualties who appear at the triage stationshould be classified as minimal because they are able toself-administer the antidote (or it can be administeredby a medic), evacuation is not anticipated, and theycan return to duty shortly.Casualties who have received the contents of allthree Mark I or ATNAA kits and continue to have dyspnea,have increasing dyspnea, or begin to have othersystemic symptoms (such as nausea and vomiting,muscular twitching, or weakness) should be classifiedas immediate. A source of continuing contaminationwith liquid agent, such as a break in protective clothingor a wound, should be given immediate decontaminationand irrigated with water or saline solution (thisprocedure is not included in the general advice aboutdecontamination in Warrior Task Training 16 ; however,the newest version of FM 8-285 5 directs caregivers toprovide treatment as described here). If the casualtyis conscious, has not convulsed, and is still breathing,prevention of further illness will ensure a quickreturn to duty. The casualty will survive unless he orshe continues to absorb agent. Also, administration ofmore atropine should help considerably. With thesemeasures, the progression of nerve agent illness canbe stopped or reversed with a minimal expenditure oftime and effort in the emergency treatment area.At the other end of the spectrum, casualties whoare seriously poisoned will usually not survive longenough to reach an MTF. However, there are exceptions.If the attack is near an MTF, casualties who areunconscious, apneic, and convulsing or postictal mightbe seen within minutes of exposure. Or, if the casualtieshave taken soman nerve agent pyridostigminebromide pretreatment, they might remain unconscious,convulsing, and with some impairment (but not cessation)of respiration for many minutes to hours. Thesepatients, as well as those in a similar condition whohave not used the pretreatment, require immediatecare. If they receive that care before circulation failsand convulsions have become prolonged (see Chapter5, Nerve Agents), they will eventually recover and beable to return to duty.Supporting this view is a report from the Tokyo subwayterrorist incident of 1995. One hospital receivedtwo casualties who were apneic with no heartbeat.With vigorous cardiopulmonary resuscitation, cardiacactivity was established in both. One resumed spontaneousrespiration and walked out of the hospital severaldays later; the other was placed on a ventilator butdid not start breathing spontaneously and died dayslater. These anecdotes suggest that when circumstancespermit, resuscitation should be attempted, for recoveryby such patients after nerve agent exposure is clearlypossible. In a contaminated area where resources, includingpersonnel, are limited, the use of ventilatorysupport and closed chest cardiac compression mustbe balanced against other factors (discussed above),but the immediate administration of diazepam andadditional atropine requires little effort and can bevery helpful in the casualty who still has recoverablecardiopulmonary function.CyanideSymptoms of cyanide poisoning depend upon theagent concentration and the duration of exposure.High concentrations of cyanide gas can cause deathwithin minutes; however, low concentrations mayproduce symptoms gradually, causing challenges forthe triage officer. Generally, a person exposed to a lethalamount of cyanide will die within 5 to 10 minutes andwill not reach an MTF. Conversely, a person who doesreach the MTF may not require therapy and could possiblybe in the minimal group, able to return to dutysoon. If the exposure occurs near the treatment area, aseverely exposed casualty might appear for treatment.The casualty will be unconscious, convulsing or postictal,and apneic. If circulation is still intact, antidoteswill restore the person to a reasonably functional statuswithin a short period of time. The triage officer, however,must keep in mind that it takes 5 to 10 minutesto inject the two antidotes needed. In a unit-level MTF,a cyanide casualty might be immediate, minimal, orexpectant; the last classification would apply if theantidote could not be administered or if circulationhad failed before the casualty reached medical care.518