The Toxicology Patient

Some knowledge of the epidemiology of poisoning (toxicoepidemiology), preferably from your area, is useful as an aid to diagnosis when the history of ingestion is unclear. Common poisonings occur commonly. The poisons ingested vary substantially between countries and between urban and rural areas (where pesticides and herbicides are more common). They are also different for adults, adolescents and children.

Medications ingested to some extent reflect what is prescribed in the community, with patients being far more likely to ingest some types of drugs per prescription than others.

A combination of knowledge of the possible toxic effects of drugs, the frequency with which these effects occur and the frequency with which these drugs are taken in overdose is a sensible approach to diagnosis.

The following paper gives a summary of factors that need to be considered when assessing and manging to toxicology patient.

Daly FF, Little M, Murray L. A risk assessment based approach to the management of acute poisoning. Emerg Med J. 2006 May;23(5):396-9. doi: 10.1136/emj.2005.030312. PMID: 16627846; PMCID: PMC2564094. PDF

Toxicology covers a wide range of presentations including deliberate self-poisoning, recreational drug misuse and abuse, accidental poisoning, occupational exposure and envenomation. Central to the management of the toxicology patient is risk assessment, as it will anticipate the poisoning severity and help guide treatment.

A thorough risk assessment is crucial in the approach to the toxicology patient and includes:

• agent/s taken
• dose
• time of ingestion
• any co-ingestions
• clinical manifestations since the exposure
• regular medications
• relevant co-morbidities

If the exposure is a deliberate self-poisoning, a mental health risk assessment should also be undertaken.

Patients are usually reliable when giving a risk assessment. In some scenarios – patient in custody, highly suicidal, using illicit drugs – there may be less willingness to divulge what was taken. In this instance, or if the patient is too sedated to give a history a collateral history can be taken from paramedics, family and friends. Empty pill packets on scene can be helpful to estimate a worst-case scenario. Sometimes contacting the patient’s regular doctor or getting a dispensing history from the patient’s chemist can be helpful to know what medications they may have access too. Access to electronic medical records can make this process easier.

Examination should be focussed on the expected toxicity given the risk assessment. In the patient where the risk assessment is unclear, examination for specific toxidromes may be helpful in determining likely agents involved in the poisoning. The below table summaries the examination findings of common toxidromes.

Specific complications of poisoning should also be considered and sought on examination:

• Aspiration
• Pressure areas
• Neuropraxia
• Rhabdomyolysis
• DVT/PE

1. Buckley NA, Whyte IM, Dawson AH, Isbister GK. A prospective cohort study of trends in self-poisoning, Newcastle, Australia, 1987-2012: plus ça change, plus c'est la même chose. Med J Aust. 2015 May 4;202(8):438-42. doi: 10.5694/mja14.01116. PMID: 25929508. PDF
2. Assessment and management of the Poisoned Patient Video Summary https://vimeo.com/428066691