New insights in the enigma of nociception and pain assessment : an evaluation of integrated pain care pathways, digital opportunities and nociceptive reflex testing
Pain is a complex medical problem. Acute pain is typically initiated through a noxious stimulus, which causes the activation of specialized somatic or visceral nociceptors and transmission of nociceptive signals to the brain through spinal pathways. As pain persists, however, the underlying pathology may evolve to a chronic disease, amplifying the response to pain, decreasing treatment success, and often leading to sensitization. The negative physiologic and psychological consequences of unrelieved pain are significant and can be long-lasting with severe consequences on overall well-being. The stress response induced by pain may include increased heart and breathing rates affecting the increasing demand for oxygen and other nutrients to vital organs. A prolonged stress state can result in detrimental multisystem effects such as stiffness, loss of muscle and joint flexibility, sleeping difficulties, anxiety, and depression. Pain adversely affects the health-related quality of life and well-being, both in the short and long term. According to the US Centers for Disease Control and Prevention, prevalence rates of chronic pain vary between 11% and 40%. A systematic review comprising studies done in the UK reported a pooled chronic pain prevalence rate of 43.5%, with the rate of moderate-to-severe disabling pain ranging from 10.4% to 14.3%. The Global Burden of Disease Study 2019 reaffirmed that the high prominence of pain and pain-related diseases is still the leading cause of disability and disease burden globally [Lancet 2020 data 1990-2019]. This includes especially lower back pain and headache besides other musculoskeletal disorders but also underlines biopsychosocial predispositions (such as depression, anxiety, and opioid use disorders) for the development of other types of chronic pain including persistent postsurgical pain (PPSP). Improved pain measurements, especially in non-communicative patients, may be an important step in the prevention and early treatment of this debilitating disease. During the past decade many new, more objective pain assessment tools have been developed, driven by increased awareness of suboptimal pain assessment. However, these novel tools often lack proper validation for clinical use. Furthermore, daily routine use is usually rather complex. In addition, early identification of patients at risk of developing chronic (postsurgical) pain and including them in a patient-centric holistic perioperative care pathway, including physical and psychological functioning evaluation as well as patient satisfaction and wellbeing assessment, are essential for the prevention and treatment of chronic pain. This dissertation describes the development, implementation, and re-evaluation of transmural perioperative care pathways for individuals at risk for pain chronification, and how these can contribute to improved pain care. Furthermore, two objective nociceptive reflex assessment tools were validated during surgery and intensive care treatment, aiming to optimize nociceptive assessment. These two assessments embrace the greater goal of persistent pain prevention and optimal procedure-related pain treatment using a biopsychosocial approach. For monitoring nociception and pain in analgosedated patients, the novel pupillometric index (PPI) was designed to assess the level of intraoperative analgesia. We were among the first to evaluate the pupil dilation reflex (PDR) using a PPI protocol during routine surgical procedures in 2018 (chapter 3.1).1 After opioid administration, propofol-sedated patients needed a higher stimulation intensity to obtain a pupillary reflex in response to the standardized automated nociceptive stimulus. Consequently, PPI score showed a reduction after opioid analgetic treatment. Moreover, the elicitation of PDR by this low-intensity standardized noxious stimulation protocol was performed without changes in vital signs before and after opioid administration in adults under propofol-based general anesthesia (chapter 3.2). In addition, in children under general anesthesia, PPI assessments appeared to be feasible (chapter 3.3).2 Subsequently, PPI was further evaluated during surgical procedures under general anesthesia using sufentanil (chapter 3.4)3 and remifentanil (chapter 3.5)[ahead of print]. Both studies showed no additional value of an opioid administration protocol depending on PPI monitoring results in outpatient surgery. In sedated critically ill patients, PDR and nociception flexion reflex (NFR) are identified as non-invasive and well-tolerated monitoring tools (chapter 4.1).4 However, results regarding the shift from NFR threshold monitoring in a perioperative setting to the mechanically ventilated, analgosedated critically ill remains unclear. Furthermore, we focused on the design and implementation of holistic pain care for patients undergoing elective surgery. In our preliminary evaluation of a web-based psychological screening tool in adolescents undergoing minimally invasive pectus surgery (chapter 5.1)5, we showed that perioperative online screening of psychological symptoms and trait characteristics could further inventorize patients at risk for prolonged pain conditions. Moreover, we showed that allocating patients to the appropriate level of care preoperatively and immediately after surgery may improve long-term outcome variables (chapter 5.2).6 Internet-based technologies and feasible, objective monitoring tools can help clinicians screen surgical patients for risk factors and initiate early treatment if necessary (chapters 5.1 and 5.2).5,6 One of the major difficulties of integrated nociceptive evaluation in the analgosedated patient, in general, is that many devices are characterized by a laborious and often time-consuming set-up, making the translation from the clinical lab to daily practice cumbersome or even impossible. Nevertheless, they might have the potential to further improve individual pharmacological treatment and outcome measurements as intraoperative nociception monitoring guidance may reduce intraoperative opioid administration and therefore might be a viable strategy to titrate opioids intraoperatively.7 However, to date, there is a paucity of evidence regarding the impact of opioid minimization or total avoidance on long-term analgetic use and outcomes (chronic pain, functionality, wellbeing). Up to now, despite advances in nociception monitoring technology and availability in recent years, their limitations override their benefits in routine anesthesia care. Future research should focus on defining how the balance between nociception and analgesia may affect patient-related outcome measurements (PROMs), and consequently, identify a critical balance where we positively or negatively affect patient outcomes. Consecutively, timing, frequency, and amount of analgetic titration and its impact on patients’ recovery can be evaluated. Additionally, when focusing on our patients’ recovery, postoperative rehabilitation, and well-being should play a more central role as primary outcome parameters taking the entire biopsychosocial package into account, in contrast to solely focusing on nociceptive monitoring, which appears up to now to be just a drop in the ocean. When embracing the knowledge and know-how to design, implement and evaluate novel pain care pathways in real-world situations, interdisciplinary teams providing biopsychosocial care will better understand and combat the burden of chronic pain.
Antwerp : University of Antwerp, Faculty of Medicine and Health Sciences , 2023
313 p.
Supervisor: Hans, Guy [Supervisor]
Supervisor: Jorens, Philippe [Supervisor]
Full text (open access)
The publisher created published version Available from 05.10.2024
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Creation 28.09.2023
Last edited 07.10.2023
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