The following definitions are relevant when treating opioid-tolerant patients as the clinical implications and management of each condition differ markedly. Tolerance, a state of adaptation in which opioid exposure induces changes that result in a diminution of one or more of a drug’s effect over time;physical dependence,predictable physiological adaptation causing a withdrawal syndrome when the medication is stopped without dose tapering, andaddiction, unpredictable aberrant drug seeking and maladaptive drug-taking behaviours. ANZCAchapter 11.7.1, p.422: See also page 2of American Society of Addiction Medicine

Condition specific perioperative analgesic issues

• Identify patients at risk. Opioid tolerant patients should be identified and their pre-admission opioid doses verified ANZCA chapter 11.7.3, p 423-424 and 426.
• Multidisciplinary team management. Management of opioid tolerant patients will involve close liaison with other treating clinicians and specialist teams as required and appropriate discharge planning ANZCA chapter 11.7.3, p 423-424.
• Opioid-induced hyperalgesia (OIH). In addition to desensitisation of anti-nociceptive pathways to opioids, sensitisation of pro-nociceptive pathways may occur, causing OIH These phenomena can significantly reduce the analgesic effect of opioids after chronic usage. ANZCA chapter 4, ‘Tolerance and hyperalgesia’ p 68; ANZCA chapter 11.7.3, p 425.
• In a patient with escalating opioid doses and unrelieved pain, it may be possible to distinguish between OIH and tolerance by administering an increased dose of opioid. Reduction in the intensity of reported pain indicates tolerance. Increase in the reported pain, indicates OIH. ANZCA, chapter 11.7.3, p 425

Evidence based recommendations specific to the condition

The evidence for the management of opioid-tolerant patients is limited and, therefore, recommendations are derived from case reports, personal experience, expert opinion, reviews and retrospective studies. ANZCAchapter 11.7.3, p 423.

Recommended treatment options

a. Systemic-based techniques

Non-opioids

Unless contraindicated, patients should receive an around-the-clock regimen of multimodal opioid-sparing analgesics, including COXIBs, NSAIDs , and paracetamolASA section V, p 254. NMDA receptor antagonists, such as ketamine, may be used to attenuate tolerance and OIH ANZCA chapter 11.7.3, p 425. Clonidine, administered orally or intravenously, will aid in symptomatic control of opioid withdrawal symptoms ANZCA chapter 11.7.3, 426.

Opioids

Peri-operative pain management should include appropriate adjustments or continuation of medications to avert an abstinence syndrome ANZCAchapter 11.7.3, p 424. Opioid requirements may be significantly higher in this patient population compared with opioid-naive patients. Oral transmucosal fentanyl citrate may be used to treat breakthrough pain in opioid-tolerant patients ANZCAchapter 6.6.2, page 162. Patient-controlled analgesia settings may require larger boluses and background infusion ANZCAchapter 11.7.3, p 424. Opioid rotation, with switching to a different opioid, has been recommended if adequate pain control cannot be achieved by increasing the opioid dose. ANZCAchapter 11.7.3, p 425.

b. Local, regional and neuraxial analgesia-based techniques

Regional local anaesthesia is recommended and forms part of multimodal pain management.Neuraxial opioids can be used, although higher doses may be required and opioid withdrawal may still occur. ANZCA chapter 11.7.3, p 426.

All “individually adapted” perioperative pain management algorithms are superior to “conventional standard” analgesia, regardless which specific analgesia technique is used.

Treatments that are not recommended

Opioid antagonists (unless for treatment of respiratory depression) and partial agonists should be avoided, as their use may precipitate acute opioid withdrawal Tramadol alone, without a strong opioid, is not recommended. ANZCA chapter 11.7.3, p 426.

Advice/guidance to patients

Patient education and support should be provided as part of in-hospital management and discharge planning, to achieve optimal analgesia with minimal side effects. ANZCA chapter 11.7.3, p 426.

Condition specific issues related to nursing/monitoring patients

• Appropriate staff training to prevent opioid withdrawal is mandatory; this condition may lead to anxiety and autonomic arousal, negatively impacting upon on the acute pain experience. ANZCA chapter 11.7.3, p 426.
• Incidence of opioid-induced nausea and vomiting may be lower compared to opioid naïve patients but risk of excessive sedation or respiratory depression may be higher ANZCA chapter 11.7, p 424.
• When assessing pain it is better to rely on functional parameters of pain (e.g. ‘how does pain interfere with e.g. ‘moving in bed’\’taking a deep breath’?’) rather than on pain scores. Expect that pain will resolve more slowly compared to opioid naïve patients. ANZCA, chapter 11, p 424.

Summary

Perioperative management of opioid-tolerant patients poses considerable challenge to all caregivers. Optimally, these patients should be identified ahead of surgery to allow for planning a safe management strategy which includes making sure that the background opioid requirements should always be met prior to commencing additional multimodal analgesia, preventing opioid (or other drugs) withdrawal syndrome and intensive psychosocial support. To achieve these goals, regular consultations and intensive inter- and intra-professional communication are recommended.

Additional references

1. Brill S, Ginosar Y, Davidson EM. Perioperative management of chronic pain patients with opioid dependency. Curr Opin Anaesthesiol 2006;19:325-331.
2. Definitions related to the use of opioids for the treatment of pain: consensus statement of the American Academy of Pain Medicine, the American Pain Society, and the American Society of Addiction Medicine.American Society of Addiction Medicine 2001. http://www.asam.org/docs/publicy-policy-statements/1opioid-definitions-consensus-2-011.pdf?sfvrsn=0
3. Kopf A, Banzaf A, Stein C. Perioperative management of the chronic pain patient. Best Pract Res Clin Anaesthesiol 2005;19(1):59-76.
4. Pogatzki-Zahn EM, Englbrecht JS, Schug SA.Acute pain management in patients with fibromyalgia and other diffuse chronic pain syndromes. Curr Opin Anaesthesiol 2009; 22:627-633.