Perineural Local Anaesthetic Catheter aftEr Major lowEr limb amputatioN Trial (PLACEMENT)

Background: Peripheral Vascular Disease (PVD) affects 20% of the population over 55, with 1-2% eventually requiring amputation. Immediate postoperative pain is a source of considerable morbidity and is associated with future Phantom Limb Pain (PLP) and Chronic Stump Pain (CSP). Opioids are the most commonly used postoperative analgesics. Whilst providing excellent pain relief, they have numerous side-effects including nausea, vomiting, constipation and delirium. A recent government funded national audit has shown postoperative amputees receive 'good' (i.e. the best) pain relief only 37.5% of the time [1]. Alternative analgesic therapies, to reduce total morphine consumption and improve postoperative pain control, are therefore desirable. The insertion of a perineural catheter (PNC) adjacent to the transected nerve at the time of amputation is simple, quick, easy to do, and allows the patient to receive a continuous infusion of local anaesthetic postoperatively. Our systematic review [2] showed this to be safe and reduce opioid consumption in observational studies. Our retrospective review has shown that it markedly reduces postoperative pain. However, our recent UK wide audit of current practice showed that PNCs are only used in 53% of all vascular units, in part due to a lack of good quality evidence on which to base practice.

Aims: This feasibility study will compare the effect of using standard analgesia and a PNC with local anaesthetic infusion after major lower limb amputation, versus standard analgesia alone. The primary outcome is postoperative pain. Secondary outcomes include opioid consumption, the incidence of opioid induced side effects (nausea, vomiting, constipation, sedation), complications, cost, quality of life (QoL) and the incidence of PLP and CSP. We also plan parallel qualitative interviews with amputees, affiliated healthcare professionals, and service users, to identify important factors for patients undergoing amputation, and so develop a Core Outcome Set (COS).

Plan of investigation: We will recruit 50 patients undergoing a major lower limb amputation (either below, through, or above the knee) for PVD from 2 recruitment sites. Patients will be randomised in a 1:1 ratio to receive optimal postoperative analgesia, with or without insertion of a PNC and local anaesthetic infusion for the first 5 postoperative days. Outcome data will be captured 3 times a day for the first 5 days, including pain scores, opioid use, nausea, vomiting, sedation, constipation and complications. Patients will be contacted 1 and 6 months after surgery to assess QoL, PLP and CSP, and total healthcare costs. Data from this pilot will be used to assess feasibility for, and estimate parameters to power, an effectiveness trial.

Summary of benefit to patients and NHS: Methods of reducing chronic postoperative pain have been identified as a key research priority by the James Lind Alliance Partnership which represents patients, the public and physicians. Our focus group identified pain and side effects from opioids as key factors influencing satisfaction following amputation, consistent with other literature [3,4]. Patients who experience significant opioid side effects stay 10% longer in hospital and are associated with increased cost to the NHS of 7-16% [5,6]. Improving immediate postoperative pain reduces levels of PLP and CSP [7], which are shown to have detrimental outcomes to the patient, the NHS and society as a whole.