Emergency Medicine

Tox i c o l o g y 175

SPECIFIC POISONS

3 Administer activated charcoal as soon as possible once the airway is
secured, to all patients with significant TCA ingestion, even with a delayed
presentation.

4 Give a loading dose of 8.4% sodium bicarbonate 1–2 mmol/kg (1–2 mL/kg),
followed by an infusion of 20–100 mmol/h (20–100 mL/h) to maintain an
arterial pH of between 7.50 and 7.55.
(i) Sodium bicarbonate is a specific antidote in TCA poisoning and
provides high concentrations of sodium ions, which help reduce
cardiotoxicity.
(ii) Indications for sodium bicarbonate administration include:
(a) cardiac arrhythmia or cardiac arrest
(b) widened QRS interval of >120 ms
(c) persistent hypotension despite saline or colloid fluid
administration.

5 Repeat the ABGs and electrolytes regularly to ensure maintenance of
alkalaemia and avoid hypernatraemia.

6 Perform repeated ECGs to monitor for cardiac arrhythmias and to ensure
the resolution of any QRS prolongation.

7 Refer patients with significant cardiovascular or CNS toxicity to the inten-
sive care unit (ICU) or coronary care unit (CCU), for ECG monitoring and
supportive care.

8 Observe patients with drowsiness alone and non-progressive or absent ECG
changes in the ED observation unit, until all clinical signs of sedation or
anticholinergic delirium have resolved.

Benzodiazepines

DIAGNOSIS

1 These are comparatively safe if taken alone. Reported deaths are associated
with mixed overdoses with other CNS depressants such as opioids and alcohol.

2 Clinical manifestations include drowsiness, respiratory depression, ataxia
and dysarthria.

3 Coma is unusual unless combined with other sedatives or alcohol, or in the
elderly.

4 Gain i.v. access and send blood for U&Es and a paracetamol level. No specific
i nvest igat ions a re requ i red u n less co-i ngest ion is suspec ted. At tach a c a rd iac
monitor and pulse oximeter to the patient.

5 Perform a baseline ECG.

MANAGEMENT

1 Give high-dose oxygen and nurse in the left lateral position to prevent aspira-
tion, unless the airway is protected.