Persistent Postsurgical Pain

This is an observational clinical study aiming to further the wider understanding of patients who develop persistent pain after Thoracoabdominal Aorta surgery, a surgical cohort who are disproportionately affected. This will be undertaken through a prospective biopsychosocial characterisation of the phenotype of patients undergoing this operation. Increasing numbers of patients are undergoing surgery on the chest for treatment of heart or lung cancer disease. Over the last twenty years, the medical community has become increasingly aware of the long-term effect of this surgery in producing persistent pain, approximately half of all survivors are still in pain around their surgical incision at three months postoperatively and beyond. There is currently no accepted method for preventing this phenomenon. The nervous system mechanisms for the development of persistent pain after surgery are unclear. Some studies suggest it may involve the patient's ability to dampen down pain signals travelling from the incision site to the brain. Humans have an in-built system that produces opiates as well as other pain-relieving molecules in response to injury, e.g. surgery. However, this response varies hugely from person to person and may even be impacted by the psychological state of the individual at the time of surgery. Some of these pain modulating mechanisms can be measured before and after surgery in patients using sensory testing, a robust and established objective method to assess patients'. Identifying patients who are most at risk of a persistent pain state will allow both academics and clinicians to investigate and better target appropriate treatments. Undertaking these longitudinal observational assessments will facilitate an improved mechanistic insight of the transition from acute to pathological pain, with the ultimate goal of improving outcomes for patients'.

Lumbar spinal surgery is common, and the incidence of spinal fusion has increased dramatically over the past three decades. Patients requiring spinal surgery are typically prescribed several analgesics, (including opioids) while awaiting surgery. Postoperatively, use of high doses of opioids or anti-inflammatory medications have drawbacks. Severe post-operative pain is reported by 45-80% of patients and rates are generally higher in the opioid tolerant patients. Regional anesthesia (blocking nerves with local anesthetics) works locally, thereby avoiding many side effects associated with other analgesics. One type of nerve block is called erector spinae plane block (ESP). Single injection nerve blocks have been found to decrease pain, nausea, and opioid consumption, while increasing patient satisfaction and quality of recovery. However, these effects only last for 24 hours or less while the worst pain occurs around 36 hours after surgery. Surgeon-placed indwelling catheters could allow infusions of local anesthetics for 54 hours. This randomized control trial seeks to assess the effectiveness of surgeon-placed ESP catheters for pain control after lumbar spine surgery. Hypothesis: Patients receiving a cESP will have less pain, improved quality of recovery, and opioid use following lumbar fusion surgery than those receiving current standard of care pain management. Methodology: Adult patients undergoing lumbar spine surgery under orthopedic surgery in Halifax will be eligible. The study will include 100 participants, randomly assigned to 2 study arms of 50 participants (1:1 basis to Ropivacaine and placebo groups). At the end of surgery, the surgeon will place the ESP catheters in all study patients under sterile conditions before closing the wound. Ropivacaine 0.5% or normal saline (placebo) 15ml will be injected through each catheter (total 30ml). In the postanesthetic care unit (PACU), two elastomeric pumps will be attached to the ESP catheters. These will be filled with either Ropivacaine 0.2% or normal saline (placebo). The elastomeric pumps are small bottle that patients can carry with them after discharge home. The pumps automatically run at an infusion rate of 10 ml/hr for 54 hours. All patients will also receive the standard of care for pain management for this patient population, which is opioid based with acetaminophen. A quality of recovery (QoR-15) questionnaire will be completed at 72 hours post-operatively. Pain, catheter complication, and opioid use data will be gathered from the patient's charts at 24, 48, and 72 hours post-operatively. At 3- and 6-month follow-ups, patients will complete the Brief Pain Inventory questionnaire. We will analyze differences in pain and opioid consumption at 24, 48, and 72 hours, quality of recovery index scores at 72 hours, postoperative complication rates, and persistent pain at 3 and 6 months.

Chronic knee pain remains a disabling disease despite current treatment strategies. There is an increase in the prevalence of osteoarthritis (OA) of the knee in the general population, presently affecting approximately 450,000 individuals in Belgium. A total knee replacement is a viable alternative for severe knee OA that does not respond to conservative therapy. Unfortunately, up to 53% of patients who undergo a total knee replacement develop persistent post-surgical pain (PPSP). There is currently no effective therapy for PPSP. A radiofrequency (RF) treatment applies high frequency current on the nerve responsible for pain conduction, resulting in an interruption of the transmission of pain. This can be applied to the nerves innervating the knee joint - the superolateral, superomedial and inferomedial genicular nerves - and could be an alternative, minimally invasive treatment for patients with knee OA who fail conservative treatments and for patients with PPSP. Data from the recent literature indicates that this treatment leads to a reduction of pain intensity and could result in an improvement of knee function, of the psychological state of the individual, and finally in an increase in health-related quality of life. Furthermore, RF of the genicular nerves could help avoid or delay a total knee replacement therefore potentially contributing to cost reduction. Both cooled and conventional RF treatments are reported in the literature to improve pain. The use of water to cool the RF electrodes results in an increased lesion size by removing heat from adjacent tissue, allowing power delivery to be increased. As a consequence, cooled RF could result in a higher chance of success and longer duration of effect. Until now, the studies performed on cooled RF are industry initiated and a direct comparison between conventional, cooled and a sham procedure is lacking. The aim of the COGENIUS trial is to investigate the effect of the two types of RF treatment on individuals experiencing chronic knee pain that is resistant to conservative treatments. For this purpose, the efficacy and cost-effectiveness of cooled and conventional RF will be compared to a sham procedure in patients suffering from knee OA and PPSP after total knee replacement.