Drug users have a different reputation among health care providers, especially in the ED. According to World Health Organization (WHO), in 2018, an estimated 269 million people, or 5.4 percent of the global population aged 15–64, had used drugs in the previous year (1). Here we will focus on opioid users, which accounts for 57.8 million people globally in 2018, specifically the acute pain management in these patients.
What do I have to know about them:
Patients with opioid dependency can have three major obstacles to pain management
- Opioid-Induced Hyperalgesia (OIH): A sensitive disorder is caused by chronic use of opioids; It can affect patients under opioid use for chronic pain control, patients under substitution therapy (methadone and buprenorphine), and those abusing heroin. OIH typically produces diffuse and not well-defined pain.
- Opioid tolerance: These patients report higher pain scores, have slower pain resolution, and experience a longer hospital stay with an increased chance of readmission, compared with opioid-naive patients. Tolerance to CNS, respiratory, and analgesic effects develops quickly, while tolerance to constipating effects may not happen. (3). Cross-tolerance is a tolerance that patients taking chronic methadone need higher doses of morphine for pain relief than occasional IV heroin users (3), suggesting a cross-tolerance between methadone and other opioids.
- Opioid withdrawal: Symptoms are caused by sympathetic activation: tachycardia, sweating, insomnia, diarrhea, and anxiety. Opioid substitution therapy (OST), usually with methadone, is crucial in treating those in rehab from opioid abuse.
How could this be a problem?
- Overtreatment: Higher dose equals more toxicity. Because of the OIH and opioid tolerance, higher doses may be necessary to relieve pain in these patients. Clinicians are generally afraid to give a higher amount of opioids due to the risk of toxicity, especially respiratory depression.
- Relapse x undertreatment: Another common fear among clinicians is inducing a relapse in an abstinent patient or OST, leading to undertreatment of pain. This, instead of opioid use, has more power to cause a relapse. (2)
Acute pain management in the chronic opioid user
- OIH (2): Multimodal analgesia, using acetaminophen, non-steroidal anti-inflammatories, and local anesthetics as “opioid-sparing drugs.” Adjuvant therapies also play an essential role, with ketamine, gabapentin, and pregabalin showing promising results in reducing OIH.
- Withdrawal (2): Methadone in small doses (10 – 20 mg) can be used to prevent withdrawal symptoms in patients who are not in OST. Methadone can cause QT-interval prolongation
- Toxicity (4): As commented above, chronic opioid users develop tolerance to respiratory and CNS effects as well, giving more space to higher doses of opioids for pain management. If toxic effects happen, provide ventilatory support and use antidotes (naloxone) if needed. Classic signs of opioid toxicity are as follows; decreased respiratory frequency (best predictor if < 12), depressed mental status, miotic pupils (however, normal pupils does not exclude opioid toxicity).
- Tolerance (3): Around the clock dosing is recommended rather than “as needed.” For patients on OST, their regular dose of methadone/buprenorphine should be continued alongside additional doses of short-acting opioids and other analgesics for adequate pain control.
Disposition to home (3)
The most crucial action here is to contact the assistant physician who is prescribing the opioids and make he/she knows what happened, how it was managed, what medications were prescribed, and in which dose. If opioids are needed for pain control at home, consider the services available in the outpatient setting:
- Immediate-release preparations are more effective for acute pain relief but carry a higher risk of abuse. If it is possible to arrange more frequent appointments, small doses of the medication can be prescribed, and the patient can be closely monitored.
- If a closer follow-up is not possible, long-acting formulations are the safest way to provide good analgesia with a smaller risk of abuse.
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References and Further Reading
- United Nations World Drug Report 2020 (available at https://wdr.unodc.org/wdr2019/)
- Quinlan J, Cox F. Acute pain management in patients with drug dependence syndrome. Pain Rep. 2017;2(4):e611. Published 2017 Jul 27. doi:10.1097/PR9.0000000000000611
- Vadivelu N, Lumermann L, Zhu R, Kodumudi G, Elhassan AO, Kaye AD. Pain Control in the Presence of Drug Addiction. Curr Pain Headache Rep. 2016;20(5):35. doi:10.1007/s11916-016-0561-0
- UpToDate: https://www.uptodate.com/contents/acute-opioid-intoxication-in-adults?search=opioid&source=search_result&selectedTitle=4~150&usage_type=default&display_rank=4
- UN World Drug Report 2020 – https://wdr.unodc.org/wdr2020/index.html
- Haber PS, Demirkol A, Lange K, Murnion B. Management of injecting drug users admitted to hospital. Lancet. 2009;374(9697):1284-1293. doi:10.1016/S0140-6736(09)61036-9
- Sahota PK, Shastry S, Mukamel DB, et al. Screening emergency department patients for opioid drug use: A qualitative systematic review. Addict Behav. 2018;85:139-146. doi:10.1016/j.addbeh.2018.05.022