Chapter 18. Poisoning
Four crucial questions must be asked:
• What was taken?
• How much was taken?
• When was it taken?
• What was taken with the overdose (e.g. alcohol)?
If possible, the paramedic should take any medicine containers found at the scene to the hospital along with the patient.
Always consider the possibility of alcohol consumption.
Poisoning in children is common, but not commonly serious. A typical case of poisoning in childhood is the accidental ingestion of a mildly toxic substance by a child aged 1–3 years. Most incidents are minor.
In the UK, the majority of children ingest therapeutic agents: paracetamol, iron, benzodiazepines, tricyclic antidepressants and the contraceptive pill are the most common. The remainder are usually poisoned by a variety of household products. The accidental ingestion is usually noticed rapidly by the parents and the children often present very soon after ingestion.
As a general rule, most cases of poisoning require no treatment other than maintenance of the vital signs. If this is achieved, the majority of patients will have a favourable outcome.
Examples of alerting clinical syndromes include:
• Rapid pulse rate – tricyclic antidepressants, antihistamines, amphetamines or other arrhythmogenic agents
• Low blood pressure – anticholinergic medications or vasodilators such as alcohol
• Increased respiratory rate – substances that cause shock, also salicylate overdose
• Decreased respiratory rate – opiate ingestion
• Dilated pupils – tricyclic antidepressants, amphetamines ingestion
• Constricted pupils – opiate ingestion
• Nasal bleeding or perioral sores – solvent abuse.
Specific poisons
Medications
Almost any medication can be harmful if taken in excess.
Benzodiazepines
Symptoms and signs
• Drowsiness
• Unconsciousness
• Respiratory depression (if taken with alcohol).
Management
• Clear and maintain the airway
• Support respiration (bag-mask ventilation if required)
• Monitor
• Transfer to hospital.
Antidotes
Although there is a specific antidote to benzodiazepines (flumazenil), there are dangers with its use. The patient may develop seizures as a result of benzodiazepine withdrawal or because other medications (e.g. tricyclic antidepressants) may also have been ingested. Should this happen, the seizures are extremely difficult to treat as the usual anticonvulsant in this situation – diazepam – will not work in the presence of the flumazenil. A further problem arises with the patient who revives following the administration of flumazenil, refuses further treatment and leaves the scene; because the effects of the flumazenil are short-lived, unlike the effects of the benzodiazepines, the patient may succumb again to the overdose, possibly when no witnesses are present to call for help.
Paracetamol
The most common over-the-counter medication taken in overdose is paracetamol. As noted previously, the great danger of this drug is that it is perceived as harmless.
Signs and symptoms
Early
• None
• Because there are often no immediately felt ill-effects after taking this drug, there may be a prolonged delay in seeking treatment and a reluctance to attend hospital.
Drowsiness suggests the ingestion of other medication, commonly a compound analgesic.
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