Tox i c o l o g y 18 7SPECIFIC POISONS4 Gain i.v. access and send blood for FBC, U&Es, LFTs, blood sugar level and
troponin as indicated clinically. Attach a cardiac monitor and pulse oxi meter
to the patient.
5 Perform an ECG and look for signs of myocardial ischaemia, infarction and
cardiac arrhythmias.
6 Request a CXR.
MANAGEMENT1 Assess and secure the airway and give high-f low oxygen.
2 Give midazolam 0.05–0.1 mg/kg i.v., diazepam 0.1–0.2 mg/kg i.v. or
lorazepam 0.07 mg/kg up to 4 mg to treat seizures, agitation and to reduce
the tachycardia, hypertension and hyperthermia.
3 Treat myocardial ischaemia with sublingual or i.v. nitrates and benzo-
diazepine sedation.
(i) Ideally arrange for percutaneous coronary intervention
(angioplasty) if myocardial infarction occurs.
(ii) Further i.v. nitrates or sodium nitroprusside may be required to
treat hypertension.
(iii) Avoid -blockers, which can worsen -adrenergic mediated
vasoconstriction.
4 Admit all patients requiring high-dose benzodiazepine therapy and patients
with evidence of cardiovascular instability for cardiac monitoring and
observation.
ORGANOPHOSPHATES
DIAGNOSIS1 Organophosphates are extremely toxic pesticides, which produce acetyl-
choline excess with muscarinic, nicotinic and CNS effects.
2 They are rapidly absorbed through the skin, bronchi and small intestine if
ingested orally.
3 Patients present with degrees of cholinergic crisis, usually within 4 h of
ingestion or exposure. Specific manifestations include:
(i) Muscarinic:
(a) bronchospasm, vomiting, pinpoint pupils, bradycardia and
hypotension
(b) excessive sweating, lacrimation, salivation, profuse diarrhoea
and urination.
(iii) Nicotinic: fasciculation, tremor, weakness, muscle paralysis,
tachycardia and hypertension.
(ii) CNS: initial agitation followed by sedation and altered mental
status leading to convulsions and coma.