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File: 970101_sep96_decls28_0019.txt
Subject: STATUS OF USAMRDC CHEMICAL CASUALTY CARE
Unit: OTSG
Parent Organization: HSC
Box ID: BX003201
Folder Title: STATUS OF USAMRDC CHEMICAL CASUALTY CARE SUPPORT
Document Number: 1001
Folder Seq #: 67
The ED50 is that dose of agent, expressed as a Ct exposure or as the actual quantity
of agent absorbed, that will produce a biological effect in half of the exposed population.
ID50 is a special case of ED50 where the biological effect is lethality.
LCt5O is an LD50 expressed in terms of a concentration-time product
PR, the a protective ratio, is a way of comparing the efficacy of protective measures
and therapies against agent exposure. The effect of any good protective measure against
a lethal agent should be to increase the LD50 of the agent for exposed animals. The PR
is simply the ratio of the agent LD50 in a protected population divided by the agent LD50
in a control population. Accordingly, a high PR indicates a good efficacy and a PR of 1.0
would indicate a worthless form of protection.
S. NERVE AGENTS (See FM 8-285 Chapter 2, Tech Memo 90-1, last 2 articles in Tech
Memo 90-2, and Tech Memo 90-3)
. Medical defense against nerve agents is well covered in these reference materials.
Three points are worth comment here:
In FM 8-285, Chapter 2, page 2-11, one of the indicators of adequate atropinization
of a nerve agent casualty is given as heart rate greater than 90 beats/minute. 'Ibis is a
much less reliable endpoint for titrating atropine than are drying of excessive respiratory
secretions and adequacy of air exchange. Experience with accidental human exposures and
animals confirms that there are multiple effects on heart rate in such cases. 'ne cholinergic
vagal and nicotinic ganglionic effects oppose each other, for example, and casualties are also
at risk for such factors as stress, hypoxia and volume depletion. There are clearly nerve
agent casualties with heart rates above 90 who require additional atropine.
As stated in Section 6, Iranian field experience with atropine generally reported use
of somewhat higher doses that those found to be adequate for even severe accidental
exposures in Western reports. Secretions and air exchange will provide good endpoints for
atropinization in individual patients.
Soldiers of two allied nations, Britain and France, now carry combination
autoinjectors containing 3 components in a single unit. In addition to atropine and the
equivalent of pralidoxime, the British autoinjector has a diazepam pro-drug that provides
the equivalent of 10 mg diazepam. 'rbe French injector contains atropine, a pralidoxime
equivalent compound named Contrathion, and 10 mg diazepam in separate chambers.
Therefore one can expect a British or French nerve agent casualty who has been given one
or more autoinjectors to have been given all 3 components of postexposure antidote therapy.
Because United States pharinacokinetic studies show a delay in rise of blood levels of
8
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Document 24 f:/Week-36/BX003201/STATUS OF USAMRDC CHEMICAL CASUALTY CARE SUPPORT/status of usamrdc chemical casualty care:12249609312729
Control Fields 17
File Room = sep96_declassified
File Cabinet = Week-36
Box ID = BX003201
Unit = OTSG
Parent Organization = HSC
Folder Title = STATUS OF USAMRDC CHEMICAL CASUALTY CARE SUPPORT
Folder Seq # = 67
Subject = STATUS OF USAMRDC CHEMICAL CASUALTY CARE
Document Seq # = 1001
Document Date =
Scan Date =
Queued for Declassification = 01-JAN-1980
Short Term Referral = 01-JAN-1980
Long Term Referral = 01-JAN-1980
Permanent Referral = 01-JAN-1980
Non-Health Related Document = 01-JAN-1980
Declassified = 24-DEC-1996