- Last edited on March 29, 2021
Opioid Intoxication
Primer
Opioid Intoxication occurs when there is a clinically significant problematic behavioural or psychological change (e.g. - initial euphoria followed by apathy, dysphoria, psychomotor agitation or retardation, impaired judgment) that develops during, or shortly after ingestion.[1] Opioid intoxication can progress into a severe overdose resulting in death.
Epidemiology
Prognosis
- Opioid intoxication can be deadly, as individuals can progress to respiratory depression, coma, and death.
Comorbidity
- The main risks of opioid toxicity respiratory depression. More rarely, there can be seizures, acute respiratory/lung injuries, and adverse cardiac events.
Risk Factors
- Males, younger age, using opioids alone, and escalating doses are risk factors for opioid intoxication.
DSM-5 Diagnostic Criteria
Criterion A
Recent use of an opioid.
Criterion B
Clinically significant problematic behavioural or psychological changes (e.g. - initial euphoria followed by apathy, dysphoria, psychomotor agitation or retardation, impaired judgment) that developed during, or shortly after, opioid use.
Criterion C
Pupillary constriction (or pupillary dilation due to anoxia from severe overdose) and at least 1
of the following signs or symptoms developing during, or shortly after, opioid use:
- Drowsiness or coma
- Slurred speech
- Impairment in attention or memory
Criterion D
The signs or symptoms are not attributable to another medical condition and are not better explained by another mental disorder, including intoxication with another substance.
Specifiers
Severity Specifier
Specify if:
- With perceptual disturbances: This specifier may be noted in the rare instance in which hallucinations with intact reality testing or auditory, visual, or tactile illusions occur in the absence of a delirium.
Signs and Symptoms
- Common signs and symptoms include euphoria, respiratory and CNS depression, decreased gag reflex, pupillary constriction (pinpoint pupils), and seizures.
- Individuals with opioid intoxication may have inattention to the environment to the point of ignoring potentially harmful or life-threatening events.[4]
Pathophysiology
- Opioid receptors are located throughout the brain, spinal cord, and gastrointestinal tract.
- Opioid receptors are abundant in the respiratory control centres, which the brainstem and higher centres including the insula, thalamus, and anterior cingulate cortex.
- In overdose, opioids alter the rhythm generation of breathing and respiratory drive
- These changes in the respiratory pattern can lead to severe respiratory depression and death.
Differential Diagnosis
- Other substance intoxication
- Alcohol intoxication and sedative-hypnotic intoxication can resemble opioid intoxication. A diagnosis of alcohol or sedative-hypnotic intoxication can be made on the absence of pupillary constriction or the lack of a response to a naloxone challenge. In some cases, intoxication may be due a combination of both opioids and alcohol (or other sedatives). In these cases, naloxone will only partially reverse the sedative effects.
- Other opioid-related disorders
- Opioid intoxication is different from the other opioid-induced disorders (e.g. - opioid-induced depressive disorder, with onset during intoxication) because the symptoms in opioid-induced depressive disorder (and other induced disorders) predominate in the clinical presentation and meet full criteria for the relevant disorder.
- Other medical conditions
- Other medical conditions can mimic opioid toxicity, including diabetic ketoacidosis, metabolic disturbances (hypercalcemia, hypernatremia), neurological diseases (meningitis), and adverse reactions to medications.
Investigations
- A general emergency medicine approach to investigations should be employed in the investigations for suspected opioid intoxication/overdose, including blood glucose, urine drug screen, a complete blood cell count (CBC), comprehensive metabolic and electrolytes, creatine kinase, and arterial blood gas (if respiratory compromise).
- Imaging studies such as neuroimaging (e.g. - if suspecting a head injury), or chest x-ray (e.g. - if suspecting lung injury) should be ordered as clinically indicated.
Physical Exam
- A routine physical examination includes looking for any new needle track marks, pinpoint pupils, signs of respiratory distress (dyspnea, wheezing), and signs of severe hypotension.
- Nausea and vomiting is also typically present
- The clinician should also look for any signs of airway obstruction (e.g. - from vomitus)
Treatment
- Attending to vital life signs, airway, breathing, and circulation is the most important first step.
- In severe respiratory depression, the individual may require intubation.
- Naloxone is the emergency treatment of choice and should be administered as soon as possible if there is high clinical suspicion for an opioid overdose.
- Naloxone can be administered via intravenous, intramuscular, subcutaneous, or intranasal routes.
- Post-naloxone administration, the individual can become combative or violent, and use of restraints may be required.
Guidelines
Opioid Use Disorder Guidelines
Guideline | Location | Year | Website | |
---|---|---|---|---|
Canadian Medical Association Journal (CMAJ) | Canada | 2018 | - | Link |
BC Centre on Substance Use (BCCSU) | Canada | 2017 | Link | Link |
META:PHI | Canada | 2019 | Link | Link |
Canadian Guidelines on Opioid Use Disorder Among Older Adults | Canada | 2020 | Link | |
National Institute for Health and Care Excellence (NICE) | UK | 2007 | - | Link |
American Psychiatric Association | USA | 2006, 2007 | - | • Guideline (2006) • Guideline Watch (2007) • Quick Reference |