page61
features
of
severe poisoning,
particularly respiratory
complications, should be admitted to hospital for symp-
tomatic treatment.
Nerve agents
Treatment of nerve agent poisoning is similar to organo-
phosphorus
insecticide
poisoning
(see
below),
but
advice must be sought from the National Poisons Infor-
mation Service.
The risk of cross-contamination is sig-
nificant;
adequate
decontamination
and
protective
clothing for healthcare personnel are essential. In emer-
gencies
involving the
release
of
nerve
agents,
kits
(‘NAAS pods’) containing pralidoxime can be obtained
through the Ambulance Service from the National Blood
Service (or the Welsh Blood Service in South Wales or
designated hospital pharmacies in Northern Ireland and
Scotland—see TOXBASE for list of designated centres).
The National
Poisons Information Service (Tel:
0844 892 0111) will provide specialist advice on all
aspects of poisoning day and night
Pesticides
Organophosphorus
insecticides
Organophos-
phorus insecticides are usually supplied as powders or
dissolved in organic solvents.
All are absorbed through
the bronchi
and intact skin as well
as through the gut
and inhibit
cholinesterase activity,
thereby prolonging
and intensifying the effects of
acetylcholine.
Toxicity
between different compounds varies considerably,
and
onset may be delayed after skin exposure.
Anxiety,
restlessness,
dizziness,
headache,
miosis,
nausea,
hypersalivation,
vomiting,
abdominal
colic,
diarrhoea,
bradycardia,
and sweating are common fea-
tures of organophosphorus poisoning. Muscle weakness
and fasciculation may develop and progress to general-
ised flaccid paralysis,
including the ocular and respir-
atory muscles.
Convulsions,
coma,
pulmonary oedema
with copious bronchial
secretions,
hypoxia,
and arrhy-
thmias
occur
in severe cases.
Hyperglycaemia and
glycosuria without ketonuria may also be present.
Further absorption of the organophosphorus insecticide
should be prevented by moving the patient to fresh air,
removing soiled clothing,
and washing contaminated
skin.
In severe poisoning it
is vital
to ensure a clear
airway,
frequent
removal
of
bronchial
secretions,
and
adequate ventilation and oxygenation;
gastric lavage
may be considered provided that
the airway is pro-
tected.
Atropine will
reverse the muscarinic effects of
acetylcholine and is given by intravenous injection in a
dose of 2 mg (20 micrograms/kg (max. 2 mg) in a child)
as atropine sulphate every 5 to 10 minutes (according to
the severity of poisoning) until the skin becomes flushed
and dry, the pupils dilate,
and bradycardia is abolished.
Pralidoxime chloride,
a cholinesterase reactivator,
is
used as an adjunct to atropine in moderate or severe
poisoning. It improves muscle tone within 30 minutes of
administration.
Pralidoxime chloride is continued until
the patient
has
not
required atropine for
12 hours.
Pralidoxime chloride can be obtained from designated
centres,
the names of
which are held by the National
Poisons Information Service (see p.
32).
PRALIDOXIME CHLORIDE
Indications
adjunct to atropine in the treatment of
poisoning by organophosphorus insecticide or nerve
agent
Cautions
myasthenia gravis
Contra-indications
poisoning with carbamates or
with organophosphorus compounds without anti-
cholinesterase activity
Renal impairment
use with caution
Side-effects
drowsiness,
dizziness,
disturbances of
vision,
nausea,
tachycardia, headache,
hyperventila-
tion,
and muscular weakness
Dose
. By intravenous infusion,
ADULT
and
CHILD
initially
30 mg/kg over 20 minutes,
followed by 8 mg/kg/
hour;
usual max.
12 g in 24 hours
Note
The loading dose may be administered by intravenous
injection
(diluted to a concentration of 50 mg/mL with water
for injections) over at least 5 minutes if pulmonary oedema is
present or if it is not practical to administer an intravenous
infusion;
pralidoxime chloride doses in BNF may differ from
those in product literature
1
Pralidoxime chloride A
Injection
,
powder for reconstitution,
pralidoxime
chloride 1 g/vial
Available as
Protopam
c
(from designated centres for organo-
phosphorus insecticide poisoning or from the National
Blood
Service (or Welsh Ambulance Services for Mid West and South
East Wales)—see TOXBASE for list of designated centres)
1.
A restriction does not apply where administration is for
saving life in emergency
Snake bites and animal stings
Snake bites
Envenoming from snake bite is uncom-
mon in the UK.
Many exotic snakes are kept,
some
illegally, but the only indigenous venomous snake is the
adder
(
Vipera berus
).
The bite may cause local
and
systemic effects.
Local
effects include pain,
swelling,
bruising,
and tender
enlargement
of
regional
lymph
nodes.
Systemic
effects
include
early
anaphylactic
symptoms (transient hypotension with syncope,
angio-
edema, urticaria, abdominal colic, diarrhoea, and vomi-
ting),
with later
persistent
or
recurrent
hypotension,
ECG abnormalities,
spontaneous
systemic
bleeding,
coagulopathy,
adult respiratory distress syndrome,
and
acute renal
failure.
Fatal
envenoming is rare but
the
potential
for
severe envenoming must
not
be under-
estimated.
Early anaphylactic symptoms should be treated with
adrenaline (epinephrine)
(section 3.4.3).
Indications
for antivenom treatment include
systemic envenoming
,
especially hypotension (see above), ECG abnormalities,
vomiting,
haemostatic abnormalities,
and marked local
envenoming such that after bites on the hand or foot,
swelling extends beyond the wrist
or
ankle within 4
hours of
the bite.
For
both adults and children,
the
contents of one vial (10 mL) of European viper venom
antiserum (available from Movianto) is given
by intra-
venous injection
over 10–15 minutes or
by intravenous
infusion
over 30 minutes after diluting in sodium chlor-
ide intravenous
infusion 0.9% (use 5 mL diluent/kg
body-weight).
The dose can be repeated after
1–2
hours
if
symptoms
of
systemic
envenoming
persist.
However,
for those patients who present
with clinical
features of
severe envenoming
(e.g. shock, ECG abnorm-
alities, or local swelling that has advanced from the foot
BNF 61
Emergency treatment of poisoning
41
Emergency treatment of poisoning