Perioperative opioids: a narrative review contextualising new avenues to improve prescribing

Opioids have dominated the management of perioperative pain in recent decades with higher doses than ever before used in some circumstances. Through the expanding use of opioids, growing research has highlighted their associated side-effects and the intertwined phenomena of acute withdrawal syndrome, opioid tolerance, and opioid-induced hyperalgesia. With multiple clinical guidelines now endorsing multimodal analgesia, a diverse array of opioid-sparing agents emerges and has been studied to variable degrees, including techniques of opioid-free anaesthesia. It remains unclear to what extent such methods should be adopted, yet current evidence does suggest dependence on opioids as the primary perioperative analgesic might not meet the principles of 'rational prescribing' as described by Maxwell. In this narrative review we describe how, using current evidence, a patient-centred rational-prescribing approach can be applied to opioids in the perioperative period. To contextualise this approach, we discuss the historical adoption of opioids in anaesthesia, our growing understanding of associated side-effects and emerging strategies of opioid-sparing and opioid-free anaesthesia. We discuss avenues and challenges for improving opioid prescribing to limit persistent postoperative opioid use and how these may be incorporated into a rational-prescribing approach.

Role of Ketamine and Opioid Rotation in the Management of Opioid Induced Hyperalgesia in a Patient With Acute Promyelocytic Leukemia

Introduction

Opioid analgesics are commonly used to manage moderate to severe cancer related pain. However long-term use of opioids has been known to lead to several unintended side effects, including opioid induced hyperalgesia (OIH) which is defined as the paradoxical increase in pain sensitization to pain stimulus following opioid exposure. Currently there are limited reports on the association between patients with cancer and OIH, and this phenomenon is rarely described in patients with leukemia or lymphoma. Here we report a patient with acute promyelocytic leukemia who developed opioid induced hyperalgesia following rapid escalation of opioids.

Case report

A 36-year-old female being treated for acute promyelocytic leukemia presented with rapidly worsening acute on chronic hip pain requiring increasing opioid requriements. Given the rapid escalation of opioid dose with minimal response and physical exam findings consistent with allodynia/hyperalgesia a diagnosis of opioid induced hyperalgesia was made.

Management and outcome

Following recognition of opioid induced hyperalgesia, the patient was managed with opioid rotation and ketamine, which resulted in prompt alleviation of pain.

Discussion

Opioid induced hyperalgesia is likely an underrecognized phenomenon in patients with cancer-related pain. A high index of clinical suspicion are necessary for diagnosis and proper management of this disease entity.

Association between fentanyl treatment for acute pain in the emergency department and opioid use two weeks after discharge

BACKGROUND

Analgesia with fentanyl can be associated with hyperalgesia (higher sensitivity to pain) and can contribute to escalating opioid use. Our objective was to assess the relationship between emergency department (ED) acute pain management with fentanyl compared to other opioids, and the quantity of opioids consumed two-week after discharge. We hypothesized that the quantity of opioids consumed would be higher for patients treated with fentanyl compared to those treated with other opioids.

METHODS

Patients were selected from two prospective cohorts assessing opioids consumed after ED discharge. Patients ≥18 years treated with an opioid in the ED for an acute pain condition (≤2 weeks) and discharged with an opioid prescription were included. Patients completed a 14-day paper or electronic diary of pain medication use. Quantity of 5 mg morphine equivalent tablets consumed during a 14-day follow-up by patients treated with fentanyl compared to those treated with other opioids during their ED stay were analyzed using a multiple linear regression and propensity scores.

RESULTS

We included 707 patients (mean age ± SD: 50 ± 15 years, 47% women) in this study. During follow-up, patients treated with fentanyl (N = 91) during their ED stay consumed a median (IQR) of 5.8 (14) 5 mg morphine equivalent pills compared to 7.0 (14) for those treated with other opioids (p = 0.05). Results were similar using propensity score sensitivity analysis. However, after adjusting for confounding variables, ED fentanyl treatment showed a trend, but not a statistically significant association with a decreased opioid consumption during the 14-day follow-up (B = -2.4; 95%CI = -5.3 to 0.4; p = 0.09).

CONCLUSIONS

Patients treated with fentanyl during ED stay did not consume more opioids after ED discharge, compared to those treated with other opioids. If fentanyl does cause more hyperalgesia compared to other opioids, it does not seem to have a significant impact on opioid consumption after ED discharge.

Regular dosing compared with as-needed dosing of opioids for management of chronic cancer pain: systematic review and meta-analysis

Opioids are the recommended form of analgesia for patients with persistent cancer pain, and regular dosing "by the clock" is advocated in many international guidelines on cancer pain management. The development of sustained-release opioid preparations has made regular dosing easier for patients. However, patients report that the intensity and impact of their cancer pain varies considerably day to day, and many try to find a trade-off between acceptable pain control and impact of cognitive (and other) adverse effects on daily activities. In acute care settings, (eg, postoperative) as-needed dosing and other opioid-sparing approaches have resulted in better patient outcomes compared with regular dosing. The aim of this study was to determine whether regular dosing of opioids was superior to as-needed dosing for persistent cancer pain. We systematically searched for randomised controlled trials that directly compared pain outcomes from regular dosing of opioids with as-needed dosing in adult cancer patients. We identified 4347 records, 25 randomised controlled trials meet the inclusion criteria, 9 were included in the review, and 7 of these included in meta-analysis. We found no clear evidence demonstrating superiority of regular dosing of opioids compared with as-needed dosing in persistent cancer pain, and regular dosing was associated with significantly higher total opioid doses. There was, however, a paucity of trials directly answering this question, and low-quality evidence limits the conclusions that can be drawn. It is clear that further high-quality clinical trials are needed to answer this question and to guide clinical practice.

Perioperative opioid analgesia-when is enough too much? A review of opioid-induced tolerance and hyperalgesia

Opioids are a mainstay of acute pain management but can have many adverse effects, contributing to problematic long-term use. Opioid tolerance (increased dose needed for analgesia) and opioid-induced hyperalgesia (paradoxical increase in pain with opioid administration) can contribute to both poorly controlled pain and dose escalation. Hyperalgesia is particularly problematic as further opioid prescribing is largely futile. The mechanisms of opioid tolerance and hyperalgesia are complex, involving μ opioid receptor signalling pathways that offer opportunities for novel analgesic alternatives. The intracellular scaffold protein β-arrestin-2 is implicated in tolerance, hyperalgesia, and other opioid side-effects. Development of agonists biased against recruitment of β-arrestin-2 could provide analgesic efficacy with fewer side-effects. Alternative approaches include inhibition of peripheral μ opioid receptors and blockade of downstream signalling mechanisms, such as the non-receptor tyrosine kinase Src or N-methyl-D-aspartate receptors. Furthermore, it is prudent to use multimodal analgesic regimens to reduce reliance on opioids during the perioperative period. In the third paper in this Series we focus on clinical and mechanism-based understanding of tolerance and opioid-induced hyperalgesia, and discuss current and future strategies for pain management.