Biomedical Engineering Reference
In-Depth Information
the care required isminimal and can easily be treated
with eye drops. The goal is to provide the necessary
decontamination (removal of clothing) and minimal
care to enable others with more serious injuries
to receive therapy. Because of the small quantity
necessary to cause injury from liquid exposure any
localized dermal effects should be considered a
potential moderate casualty and observed for further
symptoms.
6.2.4.3 Dermal and skeletal muscle effects
Generalized sweating after a large liquid or vapor
exposure is common. The first effect on skeletal
muscle is muscular fasciculations and twitching.
After a large exposure, systemic absorption results
in fatigue and weakness of muscles that is rapidly
followed by flaccid paralysis.
6.2.4.4 Central nervous system (CNS)
The CNS signs after nerve agent exposure are
due to neurotransmitter accumulation and a large
exposure will rapidly cause loss of consciousness,
seizure activity, and apnea. However, they may
be preceded by an asymptomatic period of 1-30
minutes after contact of small amounts of liquid
nerve agent with the skin. Prolonged CNS effects
(weeks to months) after nerve agent exposure are
variable and nonspecific. They may include forget-
fulness, an inability to concentrate fully, insomnia,
nightmares, impaired judgment, and depression.
Confusion and hallucinations are not a part of this
symptom cluster.
6.2.4.7 Moderate vapor or liquid exposure
Patients in this category may be able to ambu-
late with assistance because of visual disturbance,
muscle weakness, or both and may complain of
dyspnea, chest pain, or both. Nausea is frequent
and vomiting common after moderate exposure.
Localized muscle groups may fasciculate and
heart rate and blood pressure are unpredictable
with bradycardia being a rare finding. Thorough
decontamination and intramuscular or intravenous
atropine and oximes are appropriate for this group.
6.2.4.8 Severe vapor or liquid exposure
Casualties experience pronounced respiratory diffi-
culty with drooling, miosis, rhinorrhea, and
asthma-like wheezing. The upper and lower airway
secretions severely impair gas flow and oxygen
exchange and the skin is damp, pale, and dusky.
Airway resistance can be as high as 50-60 cm of
water due to bronchoconstriction and secretions.
Heart rate and blood pressure are unpredictable.
Patients may be unresponsive, convulsing inter-
mittently, and apnea may be imminent. After the
onset of flaccid muscle paralysis ongoing convul-
sive activity is no longer observed. If resources are
available, airway control, positive pressure venti-
lation along with intravenous atropine, diazepam
and oximes may be life saving.
6.2.4.5 Cardiovascular effects
Cardiovascular effects after nerve agent exposure
are variable and often not present. Parasympathetic
tone and a slow heart rate may be present and
bradyarrhythmias (first-, second-, or third-degree
heart block) may occur. However, other factors
such as fright, hypoxia, and adrenergic stimulation
may cause the heart rate may be high, low, or in
the normal range. The blood pressure may be in the
normal range or elevated from adrenergic factors.
6.2.4.6 Minimal to mild vapor exposure
Patients in this category present with any or all of
miosis, rhinorrhea, dim vision, and moderate eye or
head pain. This can occur during primary exposure
or as a secondary exposure to improperly decon-
taminated casualties. This occurred in the Tokyo
subway attack when healthcare workers secondarily
exposed to sarin vapors from victims reported dim
vision and miosis. The important decision in this
group is that the exposure was terminated by evac-
uation from the contaminated area. While exposed
6.2.5 Medical Management
Complete management of a person exposed to nerve
agent requires any or all of the following: decon-
tamination, administration of the antidotes, venti-
lation, and other supportive therapy. The condition
of the patient dictates the need for each of these
