Ultrasound-Guided Percutaneous Cryoneurolysis to Treat Pain Following Thoracic Trauma

Active cryoneurolysis of the intercostal nerve of each fractured rib along with one cephalad and one caudad will be targeted: for each nerve the cryoneurolysis device will be triggered using 3 cycles of 2-minute nitrous oxide activation separated by 1-minute defrost periods (Epimed) or for the Varian: 5.5-minute \[all but 5 participants\] or 3-minute \[5th - 12th participants; changes based on new laboratory and subsequently clinical data\] argon activation (2000 psi starting at 100% power but decreased to keep return gas flow temperature warmer than -100C) followed by a 30-second helium defrost. For the active comparator, the gas will be deployed to the tip where a drop in temperature will result in cryoneurolysis.

Due to the pragmatic design of this trial, study participation will not alter an institution's current practice. Examples of peripheral nerve blocks include paravertebral, erector spinae plane, and serratus anterior nerve blocks. The injectate through the introducer will depend on the treatment group: for participants of the control group, ropivacaine 0.5% or bupivacaine 0.375% (both with epinephrine 1:400,000) will be injected (volume determined by institutional standard-of-care). This will provide a peripheral nerve block for the control group.

Sham cryoneurolysis of the intercostal nerve of each fractured rib along with one cephalad and one caudad will be targeted: for each nerve the cryoneurolysis device will be triggered using 3 cycles of 2-minute nitrous oxide activation separated by 1-minute defrost periods (Epimed) or for the Varian: 1 cycle of 5.5 minutes \[all but 5 participants\] or 3 minutes \[5th - 12th participants; changes based on new laboratory and subsequently clinical data\] of argon and 30 seconds of helium. However, for the sham comparator, the gas will NOT be deployed to the tip, there will NOT be a drop in temperature, and NO cryoneurolysis will occur.

Due to the pragmatic design of this trial, study participation will not alter an institution's current practice. Examples of peripheral nerve blocks include paravertebral, erector spinae plane, and serratus anterior nerve blocks: for participants allocated to the cryoneurolysis group (experimental group), normal saline will be injected for the peripheral nerve block. This will result in a sham/placebo nerve block for the experimental group.