The Daily Dose • Monday, May 20

Examining the Consequences Associated with the Administration of Opioids during Surgery

By Douglas A. Colquhoun, MB ChB, from the IARS, AUA and SOCCA 2019 Annual Meetings*

The symposium, Intraoperative Opioids: Postoperative Consequences, Opioid Free Anesthesia and Nociception Index-Guided Administration, held Monday morning, included three experts in the field of perioperative pain and opioid administration and examined the consequences associated with the administration of opioids during surgery. The session was moderated and presented by Philippe Richebé, MD, PhD, Professor of Anesthesiology, University of Montreal. Additional presenters included Martin Angst, MD, Professor of Anesthesia, Stanford University, and Patricia Lavand’homme, MD, PhD, Professor of Anesthesia, Cliniques Universitaires Saint Luc.

Dr. Angst discussed, “Opioid Induced Tolerance and Hyperalgesia in Perioperative Medicine” and teased out the difference between tolerance and hyperalgesia. While both may be associated with increased consumption, in the event of hyperalgesia, this process would become circular. Increasing opioid consumption is causing the manifestation of increased hyperalgesia. In reviewing the literature, Dr. Angst acknowledged some of the limitations in the translation of animal studies to human patients. He explored some of the challenges of delineating relationships between these two phenomena, given the changes in surgical patients and opioid patterns of use – the apparent dose dependency of this phenomena. Dr. Angst reviewed some of the mechanistic pathways, which may explain this process and examined the connections between opioid-induced hyperalgesia and persistent pain after surgery and potentially long-term opioid use. He discussed the potential impact of the use of ketamine on this phenomenon.

In the second presentation, “Opioid Free Anesthesia: Future Direction?,” Dr. Lavand’homme argued that opioid-free techniques are a logical evolution in our practice. After acknowledging that opioid-free anesthesia (OFA) may not be achievable for all patients, she described that for the remainder, opioid low anesthesia (OLA) should be the goal. She disconnected the concepts of pain and nociceptive response, given that the former requires consciousness to be reported and described alternative strategies for blunting the hemodynamic responses to nociception.

Dr. Lavand’homme reviewed the limitations of intraoperative opioids in improving postoperative outcomes and pointed to mechanistic alterations of endogenous opioid systems, wide practice variation across countries and a new meta-analysis examining opioid-free anesthesia and patient outcome. While many studies have used pain scores as outcomes, Dr. Lavand’homme explained that this is an extremely limited viewpoint, and broader measures, such as using validated scales like QoR 15 (where elements such as mood, sleep and function are required) help to understand a global assessment of postoperative outcome. When these measures are considered, then the advantages of opioid-free practice are demonstrated.

Additionally, Dr. Lavand’homme reviewed emerging data on perioperative opioid use and longer-term outcomes including readmission. In closing, the audience was challenged to undertake studies to further delineate the late-term outcomes, rigorously develop protocols for opioid mitigation and adjuvant use, and define patients and procedures benefit from which agents.

In his presentation, “Intraoperative Nociception Monitors: Better Opioid Administration for Better Outcomes?,” Dr. Richebé explored the emerging concept of objective monitoring for nociception during anesthesia. In light of the previous presentations, which clearly discussed the downside risk of intraoperative opioid use, Dr. Richebé set this against the risk of undertreatment of nociception during anesthesia and how this may lead to sensitization to pain. After briefly reviewing currently available technologies, including pupilometers, skin conductance, measures derived from plethysmography (SSI), heart rate variability (ANI) and Nociception Level (NoL) (includes multiple physiologic parameters to estimate nociception), Dr. Richebé explored studies which assessed each of the available products included in emerging data. Some examples were included from his own group on the use of these monitors to guide opioid administration and subsequent reductions in opioid use intraoperatively and generally favorable PACU outcomes. Finally, Dr. Richebé outlined the exciting new horizons for these monitors and research questions necessary for the further quantification of their outcomes.

The subsequent Q&A session included interactive discussion with the audience on the practical use of non-opioid adjuvants, the impact of opioid use on cancer outcomes, differences on opioid routes of administration on outcomes, the applicability of these technologies into critical care environments, discussion of the future of these monitoring technologies and their potential limitations. The session concluded with a discussion of the potential risk of polypharmacy in widespread use of non-opioid adjuvants.

*Coverage from the symposium, Intraoperative Opioids: Postoperative Consequences, Opioid Free Anesthesia and Nociception-Index Guided Administration during the IARS 2019 Annual Meeting