Evaluating the Efficacy of the Sub-psoas Fascial Plane Block for Post-operative Analgesia Following Hemiarthroplasty

Background:

Hip fracture surgery is one of the commonest orthopaedic operations performed in the Republic of Ireland, and is associated with significant patient morbidity, mortality and health care costs. The National Irish Hip Fracture Report recorded 1,950 hip fractures in 2013, 71% were female and the highest proportions were in the 80-89 age group. It has been estimated that the overall prevalence of hip fractures is projected to increase in line with increasing elderly population and projected demographic changes.

Early remobilization has become a key integral component of the optimal post-surgical management of hip fractures. Based on the National Institute for Health and Care Excellence (NICE) guidance, the National Hip Fracture UK Database has adopted patient remobilisation on the day of or day after surgery as a key performance indicator. Early mobilisation has been shown to reduce the risk of in-hospital mortality following hip fracture and to increase the likelihood of discharge from hospital. In 2018, 20% of patients failed to achieve the early remobilisation target, due to pain and/or hypotension, factors which might have been anticipated by clear perioperative protocols and closer working between surgery and anaesthetic colleagues.

Current AAGBI guidelines describe core principles of the peri-operative management of people with hip fracture, with one of their aims recommending a peripheral nerve block immediately prior to operative fixation of a hip fracture (in the Emergency Department and at the time of surgery, provided six hours have passed between blocks). There are two peripheral nerve blocks commonly used in the perioperative setting of hip fracture repair, namely femoral or fascia iliaca block. Both techniques have been proven to be safe and efficacious, however, these peripheral nerve blocks have been associated with some residual muscle weakness and increased falls risk which further hampens the ability of a patient to remobilize post-operatively. There is a clinical need to establish a safe, reliable regional anaesthetic technique that will still offer long-acting opioid sparing analgesia, yet minimise the associated motor blockade in order to improve and facilitate remobilization. By also potentially interrupting the sympathetically mediated pain in the lower limb following hip surgery through the blockade of this lumbar sympathetic plexus, it may provide an avenue to produce significant analgesia without causing somatic sensory deficits (e.g. residual motor weakness), thereby facilitating early remobilisation and enhanced recovery. This is not a new technique, rather it is a new approach to a very well established and utilized technique (the psoas compartment block) which has been shown to be very effective, this approach is expected to be as efficacious and potentially safer than previous approaches as it avoids the nerve roots. In terms of the side effect profile of this novel approach to the PCB - there are no new expected side effects above the standard previously explained effects that can occur with any regional technique (for example, haematoma/ LAST / Neuropraxia). This approach would theoretically be associated with a lower side effect profile than previous landmark or current ultrasound-guided PCB technique as it avoids the risk profile of traversing the psoas muscle body and near the exit of the lumbar plexus nerve roots.

This study aims to follow up on the inital case series discussed above to evaluate the efficacy of the SPF block for post op analgesia in patients undergoing hemiarthroplasty surgery.

Aims and Objectives:

This will be a randomised control trial. The primary aim of this study is to further evaluate the efficacy of a sub-psoas muscle fascial plane regional block for providing adequate opioid-sparing/reducing post-operative analgesia, in comparrisson to patients who do not receive a regional anaesthesia block and standard analgesic regieme.

The secondary aim of this study is to explore patients' experience post-operatively in terms of their pain, time to remobilisation, total analgesic requirements, and quality of recovery.

Study End Points/Primary Objectives:

• To evaluate the post-operative analgesia provided by the proposed regional anaesthesia block, utilising:
• Quality of Recovery 15 (QoR15) Score
• Pain scores (Numerical rating scales, Pain Map, VAS, NRS)
• Intraoperative and Postoperative Opioid Requirements Quantification
• Time to remobilisation post-operatively
• (see supplementary material)

Study Design:

This trial will take place in the Anaesthetic and Orthopaedic Departments, University Hospital Galway. All participants will be treated with either the sub-psoas fascial plane block pre or post-operatively, or no regional anaesethesia with a standard analgesic regieme. written consent will be obtained from each participant. Where informed consent is attained, a clinical note review will take place in addition to the psoas muscle sympathetic chain block pre-operatively. Patients will be closely monitored throughout the procedure and surgery. They will be followed up in the post-anaesthetic care recovery unit to assess their pain, in addition to on day one and two on the ward where a full assessment of their recovery, pain, opioid requirements and overall post-operative course will be carried out by the anaesthetic team member involved in this study.

Study Methodology:

In this RCT, all patients enrolled will be undergoing either emergency hip surgery under the orthopaedic team in the theatre complex in University Hospital Galway. Ethical approval from the Galway Clinical Research Ethics Committee will be sought. Once approved, the procedure will be explained at length by the primary research or co-investigators to the patient and all questions will be addressed. The aim would be to provide a timeframe for the patient to consider the procedure before providing consent (i.e. during pre-operative assessment on the ward the night before or morning of their surgery and undergoing the consent process when in the theatre complex). If the patient is agreeable, verbal informed consent will be obtained. a clinical note review will take place to attain basic demographic and clinical data including diagnosis, indication for surgery, type of surgery, type of anaesthetic technique, comorbidities, preadmission opioid requirements. The procedure will be explained at length to the patient and if agreeable to proceed, the patient will be monitored closely as normally would occur in the theatre setting, they will be positioned in theatre briefly onto their lateral side. Under ultrasound-guidance the regional nerve block will be performed by the experienced consultant anaesthesiologist, whereby 30ml of 0.75% Ropivicaine will be slowly injected into the subpsoas fascial plane, whilst at all times throughout and following the procedures the patient will be closely haemodynamically monitored. The patient will be followed up in the recovery post-anaesthetic care unit up to four hours following their surgery. They will then be reviewed by the one of the co-investigators at a timeframe of 0-24 hours and 24-48 hours post-operatively to further establish their analgesic efficacy, their pain scores (see supplementary appendix), quality of recovery, time to remobilization and opioids requirements, ensuring the patient is comfortable and aiming to maximize their recovery period.

This is not a new technique, rather it is a new approach to a very well established and utilized technique - the psoas compartment block (PCB). The PCB utilizes a posterior approach whereby it traverses through the body of the psoas muscle thereby carrying the small risk profile of being near the plane of where the lumbar plexus roots exit the body of the muscle.