Inhalants Workup

Updated: May 05, 2017
  • Author: Nicholas J Connors, MD; Chief Editor: Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS  more...
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Workup

Laboratory Studies

As with every patient, the laboratory workup depends upon the severity of the illness. For anything more severe than mild intoxication, the following tests are generally recommended:

  • Pulse oximetry: Pulse oximetry assesses the degree of oxygenation and general state of pulmonary effort and function.

  • Serum chemistry: Analyses should include a standard renal panel including sodium, potassium, chloride, bicarbonate, BUN, and creatinine. Some of the inhalants, toluene in particular, cause a syndrome of distal renal tubular acidosis, with a resultant elevated anion gap, hyperchloremia, hypokalemia, and hypophosphatemia. Azotemia is also common with chronic exposure but resolves with abstinence. Hypoglycemia may be noted.

  • Arterial blood gases (ABGs): This study can be helpful in cases of inhalant intoxication. Significant acidosis, hypoxemia, or hypercarbia may suggest the need for patient intubation.

  • Complete blood count (CBC): CBC is useful as a routine screening laboratory test. Chronic users may exhibit bone marrow suppression, thrombocytopenia, and aplastic anemia.

  • Urinalysis: Elevated urobilinogen suggests hepatic involvement. Hyaline casts, elevated white blood cell counts, elevated red blood cell counts, or abnormal glucose and protein levels may suggest renal injury.

  • Creatine phosphokinase (CPK): Useful in patients with muscle tenderness or myoglobinuria to evaluate the presence of rhabdomyolysis.

  • Serum or urine toxicology: Toxicology screens may be helpful if the specific chemical involved is unknown. Specific toxicologic tests of inhalant agents are not readily available in all laboratories and may take several days to weeks to get results, so they are not helpful in the immediate diagnosis. Thiesen et al showed that toluene can be detected as urinary hippuric acid (UHA) but required correlation to blood toluene levels. [9] Chakroun et al demonstrated similar results and also detected o -Cresol and 2,5 hexandione in the urine. Consult with the laboratory regarding their ability to test for specific agents.

  • Pregnancy testing should be done in all solvent-abusing females because of the risk of embryopathy caused by these agents.

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Imaging Studies

Imaging studies can be useful adjuncts to the history, physical, and laboratory evaluation. Suggested studies include chest radiographs and head CT scan.

  • Chest radiograph: This study helps identify the etiology of respiratory difficulties associated with inhalant abuse. These include pneumothorax, aspiration pneumonia, or chemical pneumonitis with patchy or diffuse infiltrates. Chronic abusers with subsequent cardiomegaly might exhibit enlarged heart size and pulmonary edema.

  • Head CT scan: If occult trauma is suspected in the inhalant abuse patient, be liberal with CT scanning to rule out intracranial hemorrhage and occult fractures. Chronic abusers may show signs of cerebral or cerebellar atrophy.

  • MRI: Abuse of nitrites can cresult in dorsal and lateral spinal column disorders due to effects on B12 metabolism.

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Other Tests

ECG/cardiac monitoring: Many inhalants are proarrhythmic; therefore, acutely intoxicated patients should have continuous ECG monitoring. ECG often shows tachycardia, bradycardia, arrhythmias, or even cardiac ischemia with solvent abuse.

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Procedures

See the list below:

  • Follow advanced cardiac life support (ACLS) guidelines.

  • Consider oral or tracheal intubation in any patient with significantly decreased level of consciousness, inability to protect the airway, or severe oropharyngeal thermal injury secondary to inhalation.

  • Obtain peripheral or central intravenous (IV) access in all patients with suspected significant intoxication.

  • Cardioversion may be necessary if ventricular arrhythmias are present.

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