Mechanisms, diagnosis, prevention and management of perioperative opioid-induced hyperalgesia.

Opioid-induced hyperalgesia (OIH) occurs when opioids paradoxically enhance the pain they are prescribed to ameliorate. To address a lack of perioperative awareness, we present an educational review of clinically relevant aspects of the disorder. Although the mechanisms of OIH are thought to primarily involve medullary descending pathways, it is likely multifactorial with several relevant therapeutic targets. We provide a suggested clinical definition and directions for clinical differentiation of OIH from other diagnoses, as this may be confusing but is germane to appropriate management. Finally, we discuss prevention including patient education and analgesic management choices. As prevention may serve as the best treatment, patient risk factors, opioid mitigation, and both pharmacologic and non-pharmacologic strategies are discussed.

Lay abstract Opioid-induced hyperalgesia (OIH) occurs when opioid medications worsen rather than decrease pain. We present an educational review of the disorder. Although mechanisms of OIH are thought to primarily start in the brain or brainstem before traveling through the spinal cord to the area of pain in the body, there are likely many causes. We provide a suggested clinical definition and a pathway for clinical differentiation of OIH from other diagnoses to help with management. Finally, we discuss prevention including patient education and medication management choices. As prevention may serve as the best treatment, patient risk factors for OIH, decreased opioid use, and both medication and non-medication strategies are discussed.

The role of short-term, low dose intravenous ketamine infusion in Calciphylaxis.

Calciphylaxis is a small vessel vasculopathy causing subcutaneous ischemic necrosis. This condition is a recognized complication of end stage renal disease and is associated with severe pain. The mechanism of the pain generated by calciphylaxis is thought to be partly related to tissue ischemia, with a significant neuropathic component associated with neuronal hypoxic injury. The pain can be further exacerbated by the inflammatory process ensuing as a result of calciphylactic lesion infections which are commonly associated with this condition. Obtaining adequate pain relief is a challenging aspect of symptom control in calciphylaxis, and historically, patients suffering from calciphylaxis required high dose opioid medications to achieve satisfactory analgesia.This case report presents a multimodal pain management approach utilizing low dose ketamine infusion in an opioid-tolerant patient suffering from severe calciphylaxis-related pain. Ketamine is an anesthetic agent well established for its efficacy in the management of neuropathic pain in opioid-tolerant patients, and has been shown to prevent opioid-induced hyperalgesia and decrease opioid requirements. Prior published data studying pain control in calciphylaxis have mainly focused on subcutaneous ketamine administration which as noted in the literature, can be associated with infusion site complications. To the best of our knowledge, this report is first of its kind to describe successful use of ketamine infusion in treatment of acute calciphylaxis-related pain.Dose modification of ketamine is not required for patients with impaired renal function, and low dose intravenous ketamine infusion was associated with no reported adverse effects in our patient.

Treating Opioid Dependence: Pain Medicine Physiology of Tolerance and Addiction.

Inappropriate and excessive opioid prescribing practices for treatment of chronic nonmalignant pain contributed to rising rates of opioid related mortality. Effective and widely available opioid addiction treatment resources are needed to ensure successful resolution of the "opioid epidemic". This chapter outlines the basic pathophysiology of addiction as well as principles of opioid addiction management focusing on the pharmacological and nonpharmacological aspects of care. Pharmacological treatment focuses on opioid substitution therapy, with aim at prevention of opioid cravings and opioid withdrawal symptoms. Nonpharmacological treatment involves psychological and supportive approaches to addiction such as group meetings, psychological counseling, and mindfulness training.

Principles of Burn Pain Management.

This article describes pathophysiology of burn injury-related pain and the basic principles of burn pain management. The focus is on concepts of perioperative and periprocedural pain management with extensive discussion of opioid-based analgesia, including patient-controlled analgesia, challenges of effective opioid therapy in opioid-tolerant patients, and opioid-induced hyperalgesia. The principles of multimodal pain management are discussed, including the importance of psychological counseling, perioperative interventional pain procedures, and alternative pain management options. A brief synopsis of the principles of outpatient pain management is provided.