Investigations
1st investigations to order
therapeutic trial of naloxone
Test
In any patient who presents with altered mental status with bradypnoea and miosis, a trial of naloxone should be considered. If no response, then another diagnosis should be sought. In hospitalised patients, these signs are not as reliable, and use of naloxone should be more selective.[30] Naloxone can be given intramuscularly, subcutaneously, intranasally, or intravenously. If intravenous access can be safely obtained, this administration route is likely to be the safest in terms of patient management.[31]
Result
reversal of overdose signs
Electrocardiogram (ECG)
Test
In patients with significant respiratory compromise, a 12-lead ECG should be performed to look for evidence of myocardial ischaemia. QRS prolongation should be looked for in patients with propoxyphene overdose.
Result
abnormal ECG (e.g., QRS prolongation or signs of myocardial ischaemia)
Investigations to consider
chest x-ray
Test
Indicates acute respiratory distress syndrome (non-cardiogenic pulmonary oedema). Patients may present with respiratory distress and have rales on auscultation. [Figure caption and citation for the preceding image starts]: Chest x-ray of acute respiratory distress syndrome in opioid overdoseFrom the collection of Dr Dean Olsen; used with permission [Citation ends].
Result
normal size cardiac silhouette; perihilar, basilar, or diffuse alveolar infiltrates
abdominal x-ray
Test
Used to confirm suspicion of smuggled drugs in 'body packers'.[Figure caption and citation for the preceding image starts]: Abdominal x-ray showing multiple drug-filled packetsFrom the collection of Dr Dean Olsen; used with permission [Citation ends].
Result
packets of drugs seen
abdominal CT scan
Test
Used to confirm suspicion of smuggled drugs in 'body packers'.
Result
packets of drugs seen
opioid urine screen
Test
This test is not necessary in overdose and should not be used for diagnosis.
Usually detects morphine (which is a breakdown product of codeine and heroin). Other synthetic opioids may cross-react and result in a positive screen. Check with the laboratory to ascertain the specifics of the available test.
False positives and negatives are common, so interpret results with caution. Results may remain positive for several days past the initial use.
In 'body packers' with an initial negative urine screen for opioids, repeated tests may be useful in identifying or excluding leakage from ingested packages.
Result
positive for opioids
gas chromatography/mass spectrometry
Test
Most sensitive and specific test, but not useful in overdose due to a long turn-around time.
Result
positive for specific opioid
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