Chemistry Reference
In-Depth Information
3 TREATMENT
a fully conscious patient, this may be effected by vom-
iting. As a fi rst-aid measure in a child immediately
after ingestion, this may be induced by pharyngeal
stimulation. Ipecacuanha Emetic Mixture 10-15 ml for
a child, 30 ml for an adult, may be effective in inducing
vomiting.
The stomach may be washed out after the passage
of a gastric tube, but this should not be attempted after
the ingestion of corrosives or petroleum products or
in drowsy or comatose patients because of the dan-
ger of inhalation of stomach contents. The procedure
of gastric lavage is a skilled one that should only be
performed in a properly equipped emergency depart-
ment, again within about 4 hours of ingestion. If the
cough refl ex is absent or if consciousness is impaired, a
cuffed endotracheal tube should fi rst be passed to pro-
tect the lungs from inhalation of stomach contents.
The treatment of metal poisoning includes treat-
ment of the acute and chronic effects and suppression
of tissue reaction when sensitization has occurred.
The management of acute metal poisoning requires
emergency resuscitative procedures that may need to
be initiated in the work or home environment and con-
tinued in an acute treatment unit. Those principles on
which the management of the acute case of poisoning
is based, which are aspects of emergency medicine (see
Dreisbach, 1983; Vale and Meredith, 1981), will only
be briefl y referred to here, whereas therapy related to
metal poisoning will be discussed in more detail.
3.1 Prevention of Further Absorption
3.1.1 Removal from Exposure
3.1.2.2 Inactivation in the Gastrointestinal Tract
Although gastric lavage can be effectively per-
formed with warm water, some poisons may be inac-
tivated in the stomach by a specifi c antidote, and after
lavage, this may be left in the stomach in a volume not
greater than 200-300 ml. However, lavage should not
be delayed if the antidote is not immediately available.
In an emergency situation, egg white or milk will help
to partly inactivate mercury and other heavy metals
by precipitation in the stomach. Activated charcoal
will effectively absorb many poisons still present in
the stomach and will also interrupt the enterohepatic
circulation. However, it is ineffective in iron poisoning.
Five to ten grams of a thick suspension in water should
be given, and this may be repeated at intervals of 20
minutes to a maximum of 50 g. Higher doses may be
given, but these may induce vomiting of the suspen-
sion. As a fi rst-aid measure, sodium bicarbonate will
partly precipitate soluble iron salts in the stomach.
Gastric lavage should be performed as soon as possible
with desferrioxamine mesylate, 2 g in 1 liter of water.
A solution of desferrioxamine, 10 g in 50 mL water,
should then be left in the stomach. Effective precipita-
tion of the toxic barium ion can be produced by oral
administration or gastric lavage with a 10% solution
of sodium or magnesium sulfate. After the ingestion of
chromic acid, lavage should be performed with mag-
nesium carbonate. Prussian blue will chelate thallium,
and after its ingestion, a colloidal solution should be
given by duodenal tube at a rate of 250 mg/kg/day in
divided doses.
Absorption of a toxic metal may follow inhalation,
ingestion, or skin or mucosal contamination. Occupa-
tional exposure most frequently gives rise to absorption
after inhalation. After high-level inhalation exposure,
the victim should be removed immediately from the
contaminated atmosphere. Such an emergency situ-
ation may arise with volatile metal compounds such
as stibine, arsine, alkylmercury, alkyltin, and alkyl
lead compounds. After contamination of the skin with
lipid-soluble metal compounds, contaminated clothing
should be removed as soon as possible, and the con-
taminated area must be irrigated and washed, but not
rubbed, with copious amounts of cold water. Decontam-
ination may also be required for hair and fi ngernails.
In chronic, cumulative metal poisoning, it may be suf-
fi cient to remove the subject from further exposure. In
certain circumstances, for instance, a worker with mild
poisoning after exposure to inorganic mercury vapor or
to lead fume or dust may require no therapy other than
such removal. The normal excretory mechanisms will
ensure a gradual recovery from mild toxic effects.
A review of possible routes of absorption in the indi-
vidual case should include consideration of the pos-
sibility of exposure by contamination of food, drink,
cigarettes, or clothing. When this possibility exists, food,
drink, and cigarettes at the work site should be prohib-
ited, and facilities should be provided for showering
and for a complete change of clothing after each shift.
3.1.2 Minimizing Absorption from the
Gastrointestinal Tract
3.2 General Supportive Therapy
In acute poisoning, resuscitative measures have to
take precedence over all others. If the patient can be
3.1.2.1 Removal from the Gastrointestinal Tract
Within about 4 hours after ingestion, some of the
poison may be recovered by emptying the stomach. In
