Paravertebral vs. Erector Spinae Blocks for lung function in those with rib fractures

In patients with 3 or more acute rib fractures, patients will be randomised into either the paravertebral block catheter arm, or the erector spinae block catheter arm. For Erector spinae block, patients will be given the patient information sheet describing the reasons for the trial; and the procedures involved. They will be given this in person by a member of the research team (doctor or nurse) who will be immediately available to answer any questions. The equipment used will be a 16g Tuohy needle and portex catheter set. This follows local recommendations for Erector Spinae blocks and catheter insertions. The procedure will follow standard ANZCA protocol for regional anaesthesia (PS 03) with respect to monitoring and performance of regional anaesthesia. Intravenous access will be established prior to the commencement of the block. The block and catheter insertion will take place in the operating theatre complex, either in an operating theatre, or in the Post-Anaesthesia Care Unit (PACU), with appropriate monitoring and assistance from an anaesthetic technician or nurse. The practitioner will be a qualified anaesthetist who is skilled and confident in performing this technique (usually minimum 20 blocks completed). The Erector Spinae block and catheter insertion will be performed in the following manner: The patient will be positioned in the sitting position, with the side of catheter insertion marked. If this is not possible due to significant pain, sedation or other injuries, then the patient should be positioned with assistance with the side opposite the block dependent. The point of needle entry will be defined by both anatomical and ultrasound landmarks and should consider the number of rib fractures and the patient’s site of maximal pain. Catheter insertion should occur one to two spinal levels below the point of maximal tenderness or the mid-point of the fractured segments. Following application of 0.5% chlorhexidine paint, 1% lignocaine will be infiltrated subcutaneously and to deeper structures at the point of the anticipated needle entry. Under ultrasound guidance the Erector Spinae complex and the transverse processes / proximal ribs should be defined. A 16 gauge needle will be introduced to the plane between the Erector Spinae complex and the transverse process. Saline will be injected down the needle to hydro-dissect the space, following which a catheter is inserted with up to 5cm of residual catheter inserted to the Erector Spinae plane. The catheter should be secured with both tissue glue and adhesive dressing to ensure the chance of inadvertent removal is reduced. Local anaesthesia will be injected incrementally down the catheter following negative aspiration to both blood and air. This should consist of boluses of 5ml of ropivacaine 0.375% up to 20ml. An improvement in a vital capacity breath of >10% from pre-block insertion would be considered a successful block, along with decreased pain. Should the patient still fail to have an improvement in vital capacity of >10%, complain of pain or a block is not demonstrable to cold sensation at thirty minutes post catheter insertion, the procedure should be repeated. If the patient fails to have an adequate block (as defined above) after 3 attempts (whether it's from one or multiple operators) on initial insertion, then the patient will be unblinded and offered an alternative block; and/or may be offered alternative therapy, such as a patient controlled analgesia device, with the medication and dosage at the discretion of the prescriber. This will be documented in the study results. Post-insertion: Nursing staff on the hospital ward will follow hospital protocols for patients receiving continuous regional analgesia which prescribes the frequency of observations and situations in which consultation with the Acute Pain Service is required. As patients will be followed by both the Acute Pain Service and study investigators due to their enrolment in a research study, patients are likely to receive closer monitoring for side-effects. Follow up: After catheter insertion and injection of local anaesthesia, standardised programmed intermittent bolus (PIB) infusions should be charted and established by the nursing staff in the post-anaesthesia care unit. This should consist of twenty millilitres of ropivacaine 0.2% every 2 hours. If they are >75 years old, or <60kg this will be adjusted to fifteen millilitres of ropivacaine 0.2% every 2 hours. On subsequent review if the patient remains in significant pain, the prescription will be changed to twenty millilitres of bupivacaine 0.25% every 2 hours (or fifteen millilitres if >75 years old, or <60kg). If this is inadequate, a standard opioid patient-controlled analgesia (PCA) pump with either morphine or oxycodone can be charted. Should the patient continue to experience significant pain, and after discussion with the Acute Pain Service consultant, a ketamine infusion could be considered; or the catheter re-sited in the same treatment arm, with only the proceduralist being unblinded to perform the re-insertion. Should a catheter at this point fail again after re-insertion, at the discretion of the acute pain service, they may be unblinded and offered an alternative block/treatment. Their data will still be used in the study, and the failure of catheter blocks will be recorded. All patients will receive a standard oral multimodal analgesic regimen. The nature of this will be tailored to their co-morbidities, injuries (e.g. head injuries), current blood parameters (including renal function), patient allergies/adverse reactions, and other contraindications. This may include: - Paracetamol 1g orally or intravenous, regularly every 6 hours - Celecoxib 100mg orally, regularly every 12 hours - Tramadol sustained release 100mg orally, regularly every 12 hours - Morphine or oxycodone immediate release - 5-10mg orally, as required every hour - Tramadol immediate release – 50mg orally or intravenous, as required every four hours The continuous regional analgesic catheters will be removed or re-sited at the discretion of the Acute Pain Service when: - they are no longer required or; - are inadequate in providing analgesia or; - after a maximum of 4 days post-insertion to minimise risk of infection of the regional catheter. All patients will receive monitoring on the ward or critical care unit in keeping with the guidelines and protocols at Counties Manukau Health for patients receiving continuous regional analgesia. Adherence to the intervention will be monitored by reviewing nursing notes by the research team nurses, as well as the daily pain team review. Data will be collected daily on: - whether block appears to still be effective (yes or no) - dose of extra immediate-release opioid required ON TOP OF the regular simple analgesia medication prescribed above - if the patient develops pain and the spirometry values fall below 10% change in vital capacity from pre-block readings. This will be deemed a failed block, and alternative interventions as described above will be undertaken.