Anaesthesia & Intensive Care Medicine

Self-assessment Publication date: Available online 13 July 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Vijayanand Nadella

Medicolegal and social implications of practising in pain medicine Publication date: Available online 5 July 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Lorraine de Gray Abstract Pain is the most common reason for patients to see a doctor. Low social support and unemployment are common in such patients. Pain is the third leading cause for absence from work. Patients frequently seek support from their multidisciplinary pain team for welfare support and staying in or returning to employment or education. Pain physicians perform a range of intervention procedures and need to have a clear grasp of the law of consent. They are also called on to give expert evidence in personal injury and medical negligence claims where claimants have been left with chronic pain. This paper explores the legal and social infrastructure, and knowledge that should be at the fingertips of all practising in the field of pain medicine.

Non-opioid analgesics Publication date: Available online 5 July 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Bharti Seth Abstract The International Association for the Study of Pain defines pain as ‘an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in such terms of such damage’. This definition of the pain experience thus combines both the phenomenon of nociception (the sensory nervous system's response to certain harmful or potentially harmful stimuli) and pain perception (process by which pain is recognized and interpreted by the brain). The Encyclopaedia Britannicadefines an analgesic as any drug that relieves pains electively without blocking the conduction of nerve impulses, markedly altering sensory perceptions, or affecting consciousness. This selectivity is an important distinction between an anaesthetic and an analgesic drug. Analgesics can thus be broadly classified according to their role primarily on nociception as well as pain perception, both of which are intimately integrated to the pain experience. An understanding of the pain pathway is inherent to a good understanding of how therapeutic targets can act as analgesics. An overview of this is discussed in this article to understand rationale for therapeutic intervention. Opioids are substances that act on opioid receptors to produce morphine-like effects. Opioids have been used as a mainstay for pain management for centuries. As the problem of chronic pain has risen to epidemic proportions, so has the incidence of increase in opioid use as well as misuse and abuse of prescription opioids resulting in increasing morbidity and mortality. While being effective for acute pain and cancer pain management, opioids have not been very effective for the management of chronic pain or neuropathic pain. All other analgesics that do not produce analgesia through a primary effect on opioid receptors can be labelled as non-opioid analgesics (NOA). This article will aim to provide an overview of the pain pathway in relation to the therapeutic targets for providing analgesia, commonly used NAOs and their brief introduction.

The role of regional anaesthesia in the management of acute pain Publication date: Available online 4 July 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Philip Hassell, James Stimpson Abstract The role of regional anaesthesia in anaesthetic practice has become essential to enhance acute pain control, minimize the use of systemic opioids and optimize the multidisciplinary approach to enhanced recovery programmes. They are used as powerful tools to enable ambulatory surgery in a wide variety of surgical specialties and reduce the transition from acute to chronic pain. Adjuncts to local anaesthetics can be used to prolong block time and target nociception specifically allowing motor function to remain.

Assessment of acute and chronic pain Publication date: Available online 4 July 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Tim McCormick, Claire Frampton Abstract Acute and chronic pain states overlap in chronology and pathophysiology but both can remain under-managed. Assessment aims to elucidate underlying diagnosis and/or pain generators that can then guide treatment strategies. Assessment should be repeated to assess efficacy of treatments and the presence of side effects. Self-report questionnaires are available to assist in diagnosis and monitoring of pain and its related dimensions but they do not replace a thorough assessment by an experienced clinician.

The role of occupational therapy in enabling people with chronic pain to return to work or education Publication date: Available online 3 July 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Wendy Hill, Michelle Macartney Abstract Occupational therapy is based on the premise that there is an intrinsic relationship between occupations, health and wellbeing. Chronic pain restricts the performance of activities that individuals need to, want to and are expected to perform, including working or studying. Young people who have a chronic pain condition may be restricted in their participation with school or higher education which can result in them being disadvantaged regarding their future potential for employment. Work is central to most adults’ occupational identity and is therefore a key focus for occupational therapy intervention. In addition to the strategies used generally with patients, such as activity management, activity adaptation and the development of coping strategies, occupational therapy with young people and adults who want to access work and/or education will address the biological, social and psychological barriers to returning or remaining at school or work. The aim of this article is to explain the role and value of occupational therapy within the pain management team in relation to enabling patients return or remain in work or education.

The use of atypical analgesics by intravenous infusion for acute pain: evidence base for lidocaine, ketamine and magnesium Publication date: Available online 3 July 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): David Hutchins, Mark Rockett Abstract Atypical analgesics include antiepileptics and other membrane stabilizers (lidocaine and mexilitine), antidepressants, alpha-2-noradrenergic agonists, N-methyl-d-aspartate (NMDA) antagonists, corticosteroids and cannabinoids. This review will focus on three drugs commonly infused as intravenous co-analgesics. We will review the theoretical mechanisms of action, efficacy and clinical effectiveness of lidocaine, ketamine and magnesium. The evidence base supporting their use has expanded in recent years and is discussed below.

Anatomy, physiology and pharmacology of pain Publication date: Available online 3 July 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Michael J. Hudspith Abstract Pain is neither a mere sensation nor a simple warning of potential or actual bodily injury: rather it a complex emotional experience arising from integrated processing of nociceptive input subject to inhibitory and excitatory modulatory influences at multiple levels of the neuroaxis. Transmembrane protein ion-channels transduce mechanical, thermal and chemical tissue injury into electrophysiological signals that are transmitted to supraspinal structures via multiple synapses that exhibit neuroplasticity dependent upon coincident neuronal and immune cell interactions. There are therefore multiple potential pharmacological targets and the complexity of pain perception necessitates multimodal management.

Opioid mechanisms and opioid drugs Publication date: Available online 3 July 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Helen Laycock, Carston Bantel Abstract Opioids are effective in acute and cancer pain management and have increasingly been prescribed in chronic non-cancer pain despite concerns regarding long-term use and lack of efficacy. Opioid actions are via G protein coupled receptors, the activation of which leads to a variety of physiological consequences including analgesia. Prescribing opioids requires careful consideration of individual drug pharmacokinetics and pharmacodynamics, their actions across different physiological systems, side effect profiles and patient factors that influence the drug efficacy to ensure the best opioid is prescribed for each patient.

The neurobiology of chronic pain states Publication date: Available online 3 July 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Anthony H. Dickenson Abstract Plasticity enables alterations in transmission in nociceptive systems. It is this plasticity in the nervous system that can alter the linear relation between noxious stimuli and the perception of pain and is important in the switch from acute to chronic pain. In this way, a number of CNS mechanisms can alter neuronal activity, leading to abnormal ongoing and stimulus-evoked pains due to peripheral and central changes. Peripheral nerves can become sensitized, spinal cord neurons can be rendered hyperexcitable and ascending projections to higher centres can further trigger changes in descending controls from the midbrain and brainstem. Together, these changes, all of which appear to involve reversible physiological and pharmacological plasticity, can alter the relationship between an applied stimulus and the perceived response and so lead to persistent pain states.