Radiological imaging
X-ray is not a routine investigation in poisoning. Chest X-ray is used to diagnose aspiration pneumonitis due to poisoning, and to investigate a cause for hypoxia or significant oxygen requirement (eg acute respiratory distress syndrome, atelectasis). Chest and abdominal X-rays are also useful to locate radio-opaque foreign bodies in the gastrointestinal tract, such as:
- iron or potassium tablets
- button batteries—diagnosis of button battery ingestion requires a very high index of suspicion
- lead objects
- packages of drugs in body ‘packers’ and ‘stuffers’1.
Bedside echocardiography is useful to determine the relative contributions of negative inotropy and vasodilation to hypotension, and hence guides treatment choice. This is most relevant for drugs that cause both cardiogenic and vasoplegic shock (eg calcium channel blockers, beta blockers).
Computed tomography (CT) scan of the brain should not be performed routinely, but may be required to exclude other diagnoses in patients with:
- central nervous system depression or coma if the diagnosis is uncertain
- evidence or history of a significant head injury
- suspected hypoxic brain injury.