Emergency Medicine

168 Tox icolog y

ACUTE POISONING: GENERAL PRINCIPLES

respiratory rate is below 10/min and opioid intoxication is

suspected (see p. 176)

(a) beware that larger doses of naloxone may precipitate opioid

withdrawal and severe agitation in an opioid-dependent

patient.

(iii) Normal saline to treat hypotension and maintain the circulation.

If hypotension is secondary to an arrhythmia or myocardial

depression, specific drug therapy and inotropic support may be

needed.

4 Treat toxic seizures with:

(i) 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 i.v.

(ii) Second-line treatment such as phenobarbitone (phenobarbital)

10–20 mg/kg i.v. at no faster than 100 mg/min. Phenytoin is

contraindicated in the treatment of toxic seizures.

5 Gastrointestinal decontamination

This is not routine, and it is only instituted once basic resuscitative and sup-

portive care have been performed and the airway is secure.

(i) Activated charcoal:

(a) this is used to reduce the absorption of many drugs. Consider

in patients presenting within 1 h of taking a potentially toxic

overdose of an agent known to be adsorbed to charcoal

(b) give 50 g for adults (1 g/kg body weight in children) in

100–200 mL water administered orally or via a nasogastric

tube. Warn the patient that charcoal is somewhat unpalatable

and will turn the stools black

(c) charcoal administration is contraindicated when:

• an oral antidote such as methionine is to be given


• the patient has an altered level of consciousness or an
  unprotected airway


• the patient has ingested substances not adsorbed to
  charcoal, such as iron, lithium, alcohols, acid, alkali,
  petroleum, pesticides or cyanide.
  (ii) Whole bowel irrigation (WBI):
  (a) is not used routinely, but may be helpful in poisonings with:


• toxic ingestion of agents such as iron, lithium and calcium-
  channel blockers


• sustained-release or enteric-coated medications


• ‘body-packers’ who have ingested wrapped illicit drugs
  (b) is contraindicated in patients with:


• an unprotected airway


• haemodynamic instability


• bowel obstruction, perforation or ileus.