O
Opiates, urinary
Purpose of the test
The test for urinary opiates is used to identify the presence of drugs of abuse in the opiate classification. When an overdose of an opiate is suspected, urinary testing is performed in emergency room settings.
Basics the nurse needs to know
Urinary opiate testing includes identification of the presence of the drugs morphine, codeine, opium, heroin, hydrocodone (Hycodan), hydromorphone (Dilaudid), oxycodone (Roxicodone, Percocet, Percodan), and oxymorphone (Numorphan). As prescription medications, these drugs are taken for the relief of pain, but they also have a high potential for abuse, particularly when obtained from illegal sources.
The opiate screen is used medically to obtain a rapid laboratory result when treating a patient who is suspected of a drug overdose. Morphine, heroin, and codeine are the most frequently abused drugs. If the test is positive, confirmatory tests for the specific opiate are performed, particularly when the case is one involving forensics or medico-legal decisions (see also Drugs of Abuse, p 262; Appendix B, p. 658). If the test result will be part of forensic evidence, the established procedure for chain-of-custody must be followed.
Interfering factors
NURSING CARE
Pretest
The abnormal assessment findings include constricted pupils and skin that is cold, sweaty, and cyanotic. The patient’s rate of breathing is abnormally slow. When a significant amount of the opiate has been taken, the situation is a medical emergency. If the respiratory and central nervous system depression are not reversed, the patient may die of a drug overdose.
Posttest
Osmolality, plasma
Purpose of the test
Plasma osmolality is determined to assess the person’s fluid status and identify antidiuretic hormone (ADH) abnormalities.
Basics the nurse needs to know
Osmolality is a measure of the number of particles dissolved in a solution. In the blood, osmolality is created by sodium, chloride, bicarbonate, proteins, glucose, and urea dissolved in the plasma. Osmolality is affected by an increase or decrease in fluid volume or by an increase or decrease in blood particles; therefore, results are interpreted in relation to the urine osmolality and serum electrolytes.
How the test is done
A venipuncture is performed. Osmolality may also be calculated with the following equation:
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