Drug Screen

Drug Screen is a topic covered in the Davis's Lab & Diagnostic Tests.

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  • Amphetamines
  • Opiates
  • Ethanol (Alcohol)
  • Cocaine
  • Cannabinoids
  • Phencyclidine

Synonym/Acronym:
Amphetamines, cannabinoids (THC), cocaine, ethanol (alcohol, ethyl alcohol, ETOH), phencyclidine (PCP), opiates (heroin).

Rationale
To assist in rapid identification of commonly misused drugs in suspected drug overdose or for workplace drug screening.

Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction. Workplace drug-screening programs, because of the potential medicolegal consequences associated with them, require collection of urine and blood specimens using a chain of custody protocol. Analysis is performed in laboratories that are specially certified to perform workplace drug testing. The protocol provides securing the sample in a sealed transport device in the presence of the donor and a representative of the donor's employer, such that tampering would be obvious. The protocol also provides a written document of specimen transfer from donor to specimen collection personnel, to storage, to analyst, and to disposal.

Normal Findings
Method: Spectrophotometry for ethanol; immunoassay for drugs of abuse.

Ethanol: None detected

Drug screen: None detected

Critical Findings and Potential Interventions

Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.

The legal limit for ethanol intoxication varies by state, but in most places, greater than 80 mg/dL (0.08%) is considered impaired for driving. Levels greater than 300 mg/dL are associated with amnesia, vomiting, double vision, and hypothermia. Levels of 80 to 400 mg/dL are associated with coma and may be fatal. Possible interventions for ethanol toxicity include administration of tap water or 3% sodium bicarbonate lavage, breathing support, and hemodialysis (usually indicated only if levels exceed 300 mg/dL).

Amphetamine intoxication (greater than 200 ng/mL) causes psychoses, tremors, convulsions, insomnia, tachycardia, dysrhythmias, impotence, cerebrovascular accident, and respiratory failure. Possible interventions include emesis (if orally ingested and if the patient has a gag reflex and normal central nervous system [CNS] function), administration of activated charcoal followed by magnesium citrate cathartic, acidification of the urine to promote excretion, and administration of liquids to promote urinary output.

Cocaine intoxication (greater than 1,000 ng/mL) causes short-term symptoms of CNS stimulation, hypertension, tachypnea, mydriasis, and tachycardia. Possible interventions include emesis (if orally ingested and if the patient has a gag reflex and normal CNS function), gastric lavage (if orally ingested), whole-bowel irrigation (if packs of the drug were ingested), airway protection, cardiac support, and administration of diazepam or phenobarbital for convulsions. The use of beta blockers is contraindicated.

Heroin and morphine are opiates that at toxic levels (greater than 200 ng/mL) cause bradycardia, flushing, itching, hypotension, hypothermia, and respiratory depression. Possible interventions include airway protection and the administration of naloxone (Narcan).

PCP (phencyclidine) intoxication (greater than 100 ng/mL) causes a variety of symptoms depending on the stage of intoxication. Stage I includes psychiatric signs, muscle spasms, fever, tachycardia, flushing, small pupils, salivation, nausea, and vomiting. Stage II includes stupor, convulsions, hallucinations, increased heart rate, and increased blood pressure. Stage III includes further increases of heart rate and blood pressure that may culminate in cardiac and respiratory failure. Possible interventions may include providing respiratory support, administration of activated charcoal with a cathartic such as sorbitol, gastric lavage and suction, administration of IV nutrition and electrolytes, and acidification of the urine to promote PCP excretion.

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