Investigations
1st investigations to order
ECG
Test
ECG should be performed in all patients with tachycardia, chest pain, or dyspnoea following cocaine use.[22][23]
The sensitivity of an ECG for picking up myocardial infarction following cocaine use was found to be only 35.7% in 1 study.[31] Therefore, cardiac enzymes should be obtained in all patients with suspicion of myocardial infarction, regardless of ECG findings.[22][24][25]
Result
normal, sinus tachycardia, early repolarisation pattern, supraventricular tachycardia, lengthened QRS interval, prolonged QT interval, ventricular dysrhythmia including asystole, ischaemic changes
bedside serum glucose
Test
Hypoglycaemia should be excluded immediately in all patients. Hypoglycaemia may occur at glucose <2.8 to 3.3 mmol/L (<50 to 60 mg/dL) in non-diabetics and at higher levels in the diabetic patient.
Hyperglycaemia (glucose >6.7 mmol/L [ >120 mg/dL]) may be present; however, it is often indicative of the hyperadrenergic state, and need not be treated under most circumstances.
Result
normal, hypoglycaemia or hyperglycaemia
serum creatinine
Test
Elevated creatinine (greater than patient's baseline, if known, or >106 micromol/L [>1.2 mg/dL]) may indicate volume depletion or rhabdomyolysis.
Result
elevated in volume depletion or rhabdomyolysis
urea
Test
Elevated urea (>6.4mmol/L [>18 mg/dL]) may indicate hypovolaemia or renal insufficiency.
Result
elevated in hypovolaemia or renal insufficiency
serum creatine phosphokinase (CPK)
Test
Elevated total CPK, usually in the thousands of international units/L, is indicative of rhabdomyolysis. An elevation of the creatine kinase-MB fraction, specific to cardiac muscle, signifies myocardial infarction, but this test has been largely supplanted by troponin assays. See Rhabdomyolysis.
Result
elevated in rhabdomyolysis
serum troponin
Test
Troponin (upper limit of normal varies depending on assay) should be obtained in all patients complaining of chest pain or shortness of breath, and in those with moderate to severe vital sign abnormalities to determine whether myocardial infarction has occurred.[22][24][25] High-sensitivity cardiac troponin (hs-cTn) is the preferred biomarker to rapidly detect or exclude myocardial injury in any patient presenting with chest pain.[26] Hs-cTn demonstrates greater sensitivity and negative predictive values than previous generation assays.[26] Hs-cTn can be elevated as a result of a variety of ischaemic, non-coronary cardiac, and non-cardiac causes of cardiomyocyte injury, but cocaine use in itself does not elevate hs-cTn.[26][28]
Result
serum troponin is elevated in myocardial infarction; hs-cTn concentration >99th percentile upper reference limit, which is also assay-dependent, indicates myocardial injury. To interpret a cardiac troponin assay, clinicians must be familiar with the assay(s) they use in their practice. Refer to local protocols
chest x-ray
Test
CXR should be performed in patients with chest pain, shortness of breath, or hypoxeamia.[25]
Pneumothorax and pneumomediastinum are rare complications of cocaine use. They are probably related to the practice of some cocaine users to perform a Valsalva manoeuvre following insufflation or inhalation, not a direct effect of the drug itself.
A haemorrhagic alveolitis (crack lung) rarely occurs but is well described in the literature.
Result
normal, pneumothorax, pneumomediastinum or haemorrhagic alveolitis
CT scan of brain
Test
CT scan should be performed in patients who are obtunded, present with seizures, or complain of headache.[25]
Subarachnoid, intraventricular, and intraparenchymal haemorrhage, or cerebral infarction may rarely complicate cocaine use.[32]
Result
subarachnoid, intraventricular, and intraparenchymal haemorrhage; cerebral infarction
Investigations to consider
urine cocaine assay
Test
The urine cocaine assay at most institutions is an immunoassay for benzoylecgonine, a principal metabolite. The test is nearly 100% sensitive and specific for cocaine exposure in the past 2 to 3 days. However, cocaine poisoning is a clinical diagnosis.
The urine cocaine assay does not affect acute management.[30] Supportive measures should be instituted as soon as the diagnosis of cocaine poisoning is suspected.
The cocaine assay may be helpful when child abuse or neglect is suspected or to uncover a substance use history. A negative assay in a body packer or body stuffer indicates that no packet rupture has occurred.
Result
detection limit of >300 nanograms/mL of benzoylecgonine
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