UltrasouNd-guided Percutaneous Intercostal Nerve Cryoneurolysis for Analgesia Following Traumatic Rib Fracture

Traumatic rib fractures (i.e., broken ribs caused by a physical injury) are common and very painful. They also often lead to serious complications, more time spent in hospital, and can even lead to death. Even after rib fractures have healed, they can lead to long-term pain and a lower quality of life.

A technology called cryoneurolysis, which acts to freeze nerves causing pain using a small tool which can turn very cold, is a promising new way to manage rib fracture pain. This study is a test with a small number of people to see if it is feasible to use this technology for patients with rib fractures. If this is successful, we will recruit more people for a larger study to see if cryoneurolysis, along with standard pain control techniques, is better at stopping pain, compared to just the normal techniques alone. Participants in our study will be asked to rate their pain, and record pain medications that they take for 3 months after their pain procedure.

More than 100,000 people a year suffer from traumatic rib fractures. Pain from rib fractures impairs the ability to inspire deeply and cough effectively, predisposing patients to severe, potentially life threatening complications and increased healthcare costs. For many patients, this pain can also persist long after the acute injury has healed, delaying recovery and reducing quality of life.

Current pain interventions, including multimodal analgesia and local anesthetic-based nerve blocks, are useful, but are limited by a short duration of effectiveness, and/or risk of complications. Cryoneurolysis (CN) is a new method to control pain which acts to freeze intercostal nerves (ICNs) associated with fractured ribs using a handheld device. This freezing action causes neurons to undergo Wallerian degeneration distally from the site of ablation and thus exhibit an extended but reversible block.

This study is a single-site, randomized, pilot study to assess the feasibility of recruitment, randomization, and protocol adherence of providing cryoneurolysis for patients with traumatic rib fractures. Secondary data from the pilot trial designed to assess the effectiveness of the intervention (pain scores, opioid usage, etc.) will be included in the analysis of the full trial if feasible. The objective of the full trial is to demonstrate that cryoneurolysis of ICN, in addition to standard analgesic practice, provides superior, prolonged analgesia.

Participants (individuals aged 18-85, with 3-8 unilateral traumatic rib fractures) will be randomized 1:1 in blocks of 4, stratified by number of rib fractures (\> 4 or ≤4) and the presence/absence of flail segment, to receive the current standard of practice for rib fractures (multimodal analgesia and erector spinae plane (ESP) catheter infusion) with or without the addition of CN. Participants in the standard care group will receive a sham CN procedure to maintain blinding.

All participants (both groups) will receive standard of care analgesia. Specifically, an ultrasound-guided ESP catheter will be placed as per standard protocols. 20cc of 0.5% ropivacaine and 1% lidocaine will be injected through the catheter, followed by a basal infusion of 2 cc/hr of 0.2% ropivacaine (to maintain catheter patency) with an on demand patient controlled regional anesthesia (PCRA) dose of 10cc 0.2% ropivacaine available hourly until patient has met criteria for APS discharge or pain is controlled such that PCRA use is \< 2 boluses over 12 hrs and NRS \< 3 with deep breathing and coughing.

Standard multimodal analgesia including Tylenol 1000mg QID, Celebrex 200mg BID (or ketorolac 7.5 QID), Pregabalin 50mg BID, and/or PRN oral hydromorphone (1-4mg) will also be provided. Additional analgesics include intravenous ketamine at a dose of 0.1-0.2 mg/kg/hr of lean body weight in the event of consistent NRS pain scores \> 6, and up to 0.05 mg/kg of intravenous midazolam for anxiolysis and 1mcg/kg of intravenous fentanyl for comfort during positioning, as required.

Participants will remain in the study for 3 months from the date of the block procedure. They will be followed daily while in hospital and using a pain diary following discharge (weekly pain scores and daily opioid usage). Additionally, follow-ups will be completed at 1h, 24h, 48h, 1 week, 1 month, and 3 months post block procedure.

Eligibility Criteria:
Inclusion Criteria:

* Aged ≥18
* Unilateral traumatic rib fractures (3 to 8)
* Candidate for ESP block catheter
* Within 48hrs of admission to hospital

Exclusion Criteria:

* Lack of patient consent; unlikely to comply with follow up
* Unable to use Patient Controlled Regional Analgesia (Ventilated/sedated patients or Moderate to severe traumatic brain injury)
* Chronic pain (opioid use \> 30mg oral morphine equivalent per day)
* Substance use disorder
* CrCl \< 50
* BMI \> 45
* Significant distracting injuries (unreduced long bone fractures, unstable pelvic or spine fractures and patients requiring trauma laparotomy- also preclude positioning for block placement (lateral decubitus or sitting up))
* Contraindications for ESP catheter placement (pre-existing medical/neurological/hematologic diseases, localized infection/trauma at site of intervention, allergy to amide local anesthetics)
* Contraindications to CN (cryoglobulinemia, paroxysmal cold hemoglobinuria, multiple myeloma and cold urticarial).
* Unable to return to Trauma Recovery Clinic (in-person or virtual) at 3 months