Early Percutaneous Cryoablation for Pain Control After Rib Fractures Among Elderly Patients
Phase: NA
Conditions: Rib Fractures
Sponsor: Stanford University

 
 
 
Clinical Protocol 
E-PERC: Early Percutaneous Cryoablation for Pain Control after Rib Fractures for Elderly Patients 
NCT: NCT04482582 
Investigator: Dr. Joseph Forester 
April 2, 2021 
Revised: September 27, 2023 
 
 

 
 
Early Percutaneous Cryoablation for Pain Control after Rib Fractures for Elderly Patients (E-PERC) 
 
Trauma team: Ya-Chen Lee MS, ACNP-BC; Rachelle Rosales BSN, RN, PCCN; Kris Gallegos RN TCRN; 
Michelle Woodfall MS RN CEN CCRN; ; David A Spain MD; Joseph D Forrester MD MSc (Principle 
Investigator) 
 
Interventional Radiology: Nishita Kothary MD 
 
Study Coordination Team: Sydney Guthrie-Baker, Alexandra Myers, Anisha Abreo 
Biostatistician: Michelle Earley 
 
Background: 
Rib fractures are common injuries sustained after trauma1–3 – in 2017, nearly 500,000 emergency 
department visits in the United States involved a patient with rib fractures4.  In addition to causing morbidity 
and mortality in injured patients2, rib fractures have been associated with chronic pain and prolonged 
disability5–7.  The prevalence of adverse outcomes associated with rib fractures rises with age starting as early 
as the fifth decade of life8 and increases significantly in patients over 65 9–12.  A number of institutions13–15, 
including our own16, have implemented evidence-based, multidisciplinary care pathways to  improve clinical 
outcomes in patients with rib fractures.  These care pathways may be particularly beneficial to elderly patients.  
Tignanelli et al.17 recently reviewed the treatment of over 625,000 rib fracture patients in 777 US trauma 
centers and found that surgical stabilization of rib fractures (SSRF), intensive care unit (ICU) admission of 
patients over 65 years old, and neuraxial blockade in patients over 65 resulted in decreased mortality.   
SSRF requires open reduction and fixation of rib fractures to restore anatomic alignment of fracture 
fragments in order to decrease pain and restore respiratory mechanics15.  Current consensus guidelines18 
recommend SSRF in patients with physiologic flail chest and multiple rib fractures with bi-cortical displacement, 
but do not address management of elderly patients specifically.  Zhu et al.19 conducted a propensity matched 
retrospective study of 758 patients over age 65 who presented with rib multiple fractures and found a 
statistically significant reduction in mortality among elderly patients who underwent SSRF.  While these 
findings suggest SSRF may be beneficial in geriatric populations, this remains a higher risk surgical population.  
Frailty, defined as a decrease in physiologic reserves20, is common among persons >65 years and a known 
correlate of worse surgical outcomes in this population21.  Taken together, these findings suggest that SSRF 
may not be the treatment of choice for all geriatric patients.     
In addition to the risks associated with surgery, there are inadequacies associated with the non-surgical 
components of existing rib fracture care pathways. Pain medications can be problematic as adequate 
analgesia must be balanced with the risks of over-sedation and respiratory depression with gabapentin and 
narcotics. Non-steroidal anti-inflammatory drugs can exacerbate underlying renal dysfunction. Neuraxial24 and 
regional anesthesia25 blocks are effective but technically demanding and relatively short-lived. ICU admission 
exposes frail, elderly patients to deleriogenic environments26 and ICU-associated pathogens. There is, 
therefore, a critical need for durable, long-term pain control for elderly patients with rib fractures that are unable 
to undergo surgical fixation in order to minimize their risk of complication and return to baseline functional 
capacity as soon as possible.   
Cryoablation of intercostal nerves offers a minimally invasive method to deliver long term pain control.  
Direct application of cold to nerves destroys nerve axons, resulting in Wallerian degeneration of the distal 
nerve without distorting epineurial or perineurial tissue.  Preservation of peri- and epineurium provides a 
scaffold for peripheral nerve regeneration which provides reversible anesthesia lasting months27.  Cryoablation 
of intercostal nerves under direct visualization has been validated for long-term analgesia after video assisted 
thoracoscopic surgery (VATS) for pectus excavatum in children reducing procedural pain and length of stay 

 
 
28,29.  More recently, case reports have explored use of VATS to perform intercostal nerve cryoablation as an 
anesthetic adjunct following SSRF30.  Image-guided cryoablation of intercostal nerves has been shown in case-
reports and series to decrease chronic pain following thoracotomy31,32.  These findings suggest a role for 
percutaneous, imaging guided intercostal nerve cryoablation in patients with rib fractures who are poor 
candidates for SSRF and VATS-guided intercostal nerve cryoablation.  
 
In 2019, Stanford received 3,132 trauma activations. Of these, 495 (16%) patients had rib fractures, 
and 267 (9%) had rib fractures and were > 65 years. Over the last 6 months, we have used cryoablation of the 
intercostal nerve as an analgesic adjunct to SSRF among 6 patients with promising results. Given our 
experience with VATS-guided cryoablation of intercostal nerves, we hypothesize that CT-guided cryoablation 
of the intercostal nerve would provide a minimally invasive method of long-term pain control for these high-risk 
surgical patients, affording the benefits of cryoablation of the intercostal nerves, without the risk of surgery. 
 
Study design: 
We propose a randomized-controlled study comparing CT-guided percutaneous cryoablation of the intercostal 
nerves with standard-of-care to standard-of-care alone in elderly patients with acute rib fractures following 
chest wall trauma.   
 
Enrollment: 
Patients will be prospectively enrolled by the trauma service at the time of admission and followed through their 
hospital course. A random number generator will be used to select traumatically injured patients > 65 years 
with rib fractures to either standard care or percutaneous cryoablation with standard care.  Clinical data will be 
collected from patient’s charts using a standardized reporting tool and quality-of-life data will be collected by 
telephone or during patient visits to the chest wall injury clinic.  
 
Treatment group: 
A consult would be placed to interventional radiology for evaluation for CT-guided cryoablation of the 
intercostal nerves.  Patients who are deemed to be adequate candidates will be taken urgently for cryoablation 
(<72 hours from enrollment).  All subsequent care will be carried out by the trauma service according to 
standard of care.  
 
Protocol Amendment September 2023 
Intent to treat Enrollment Strategy:  
Patients who meet all inclusion criteria, consent to participate in the trial, and are thus enrolled but who 
ultimately do not receive the procedure will be included in the treatment group and followed as all other 
participants in this group, per an intention-to-treat enrollment strategy. This change was requested on 9/22/23 
due to issues of scheduling procedures on the weekends impacting enrollment and patients not tolerating lying 
prone.  
 
Control group: 
All patient care will be carried out by the trauma service according to standard-of-care.  This includes 
admission to the ICU or ward at the discretion of the attending physician.  Multimodal pain control including 
acetaminophen, gabapentin, and narcotic, and evaluation for neuraxial or regional nerve block by the 
anesthesia service as dictated by current clinical protocol.   
 
Study Inclusion criteria include: 
● patients >65 years with any acute rib fracture  
● pain score >5 with deep inspiration 

 
 
 
Study Exclusion criteria include: 
● if only ribs broken are ribs 1,2 or 10,11, 12 
● radiographic evidence of metastasis to ribs 
● Glasgow Coma Scale (GCS) score <13 
● patients undergoing SSRF 
● rib fractures located <3 cm from spinous process 
● coagulopathy (INR>1.5, Plt<100) 
● other factors precluding cryoablation at IR attending’s discretion 
 
 
Treatment: Patient will go to interventional radiology for percutaneous cryoablation of ribs 3-9 on affected side. 
The Endocare™ 1.7mm Round Ice PerCryo™ Croprobe will be used. A post procedure chest x-ray will be 
obtained.  
 
Power:  
A recent study by Pieracci et al.33 examined impact of SSRF vs. nonoperative management on outcomes 
among patients with >3 ipsilateral bicortical rib fractures.  The authors found a reduction in numeric pain score 
(NPS) from 6.3 to 4.7 (p<0.01) and 4.5 to 2.9 (p<0.01) at one and two weeks, respectively, in patients who 
underwent SSRF.  Assuming a standard deviation of 3 (assumption made by Pieracci et al.), 110 patients 
would be required to detect a 20% difference with alpha= 0.05.  We estimate that the Stanford Trauma Service 
sees approximately 100 patients per year who would qualify for this study assuming a third of the persons 
aged >65 years with rib fractures would both qualify and consent to the study. There were 267 patients aged 
>65 years with rib fractures admitted in 2019.  
 
Assessments: 
 
Acute pain and pulmonary function: 
Acute pain will be assessed by numerical pain score (NPS).  Patients are asked to rate their pain on a scale of 
0-10 with 0 being no pain and 10 being the worst pain.  NPS is currently assessed as part of ongoing nursing 
evaluations and is recorded in the patient’s chart.  Pulmonary function will be assessed by incentive spirometry 
which is also charted in daily progress notes. 
 
Chronic pain:  
The McGill Pain Questionnaire (MPQ) is a validated 20 question instrument to quantify subjective pain.  The 
scoring system yields a pain rating index (PRI) score between 0 and 50 used to temporally track pain34.  This 
system has been in patients with chest wall injury5,35 with PRI ≥8 being significant for chronic pain.  MPQ PRI 
will be calculated upon study enrollment, at the time of hospital discharge, and at 30, 90, and 365 days 
following hospital discharge. 
 
Long-term function: 
The Glasgow Outcome Scale Extended (GOS-E)36 is a widely used, standardized instrument developed to 
assess long-term outcomes in patients following traumatic brain injury (TBI).  The scale provides a composite 
score (1-8, see Figure 2) based on multiple domains including social activities, ability to engage in 
relationships. Work status, ability to care for oneself and mobility within the community.  The 12-Item Short-
Form (SF-12) Health Survey37 is another validated, widely used composite score to gauge overall health based 
on 8 domains.  Both of these scales have been used in patients who have sustained chest wall trauma5,35.  

 
 
Patients will be assessed using the GOS-E in person at scheduled clinic visits or by telephone at 30, 90 and 
365 days following hospital discharge. 
 
Endpoints: 
The primary endpoints of the study would be daily numeric pain score and length of hospital stay.  Secondary 
endpoints for the study would include 30-day mortality, need for ICU, use of narcotic equivalents, 30 day rib-
specific (delayed hemothorax, pneumothorax, pneumonia, pain) readmission, as well as long term pain and 
quality of life as measured by MPQ PRI, GOS-E and SF-12 scores at 30, 90, and 365 days. 
 
Variables: 
 
Variable 
Dictionary* 
Demographic  
 
MRN Numerical 
Age Numerical; years  
Sex Categorical; M=0, F=1  
Arrival time MM/DD/YYYY/24HR time 
Blunt vs Penetrating Categorical; Blunt = 0, Penetrating = 1 
Mechanism Categorical; Fall = 0, MVC =1 , MCC=2, bicycle = 3, pedestrian vs 
auto = 4, blunt assault = 5, GSW= 6, Stab = 7, other = 8  
Injury severity score Numerical 
Admission GCS score Numerical 
Intracranial hemorrhage Categorical; N=0, Y=1 
Facial fracture Categorical; N=0, Y=1 
Spine fracture Categorical; N=0, Y=1 
Pelvis fracture Categorical; N=0, Y=1 
Long bone fracture Categorical; N=0, Y=1 
Solid organ injury Categorical; N=0, Y=1 
BCVI Categorical; N=0, Y=1 
Randomization 
 
Median pain score in first 24 hours Numerical 
Lowest pain score in first 24 hours Numerical 
Highest pain score in first 24 hours Numerical 
Incentive spirometry Numerical; cc 
Cough Categorical; 0 = none, 1 = weak, 2 = moderate, 3 = strong 
Randomization group Categorical; 0 = standard of care, 1 = intervention 
Intervention time MM/DD/YYYY/24HR time 
Pain control pre-procedure 
 
Daily MME before intervention Numerical 
Thoracic epidural Categorical; N=0, Y=1 
Continuous intercostal nerve block Categorical; N=0, Y=1 
Paraspinal or paravertebral block or 
catheter 
Categorical; N=0, Y=1 
Ketamine gtt Categorical; N=0, Y=1 
Liposomal bupivacaine rib block Categorical; N=0, Y=1 
Lidocaine gtt Categorical; N=0, Y=1 
Lidocaine patch Categorical; N=0, Y=1 
Gabapentin Categorical; N=0, Y=1 
NSAIDs Categorical; N=0, Y=1 
Acetaminophen Categorical; N=0, Y=1 
Pre-existing illness 
 

 
 
COPD or asthma Categorical; N=0, Y=1 
BMI > 30 kg/m2 Categorical; N=0, Y=1 
Current smoker Categorical; N=0, Y=1 
Diabetes Categorical; N=0, Y=1 
History of chronic chest wall pain Categorical; N=0, Y=1 
Prior rib fractures Categorical; N=0, Y=1 
Rib-specific injuries 
 
Side of rib fractures Categorical; 0 = Left only, 1 = Right only, 2 = Bilateral 
Open vs closed Categorical; N=0, Y=1 
Clinical flail chest Categorical; N=0, Y=1 
Radiographic flail  Categorical; N=0, Y=1 
Number of rib fractures on L  Numerical 
Location of fractures on L Categorical; anterior = 0, lateral = 1, posterior = 2 
Severity of rib fractures on L Categorical; undisplaced = 0, offset = 1, displaced = 2 
Number of rib fractures on R  Numerical 
Location of rib fractures on R Categorical; anterior = 0, lateral = 1, posterior = 2 
Severity of rib fractures on R Categorical; undisplaced = 0, offset = 1, displaced = 2 
Pneumothorax Categorical; N=0, Y=1 
Chest tube in place Categorical; N=0, Y=1 
Hemothorax Categorical; N=0, Y=1 
Sternal fracture Categorical; N=0, Y=1 
Clavicle fracture Categorical; N=0, Y=1 
Scapula fracture Categorical; N=0, Y=1 
Hospitalization  
 
Hospital length of stay Numerical; days 
Admission to ICU Categorical; N=0, Y=1 
Length of ICU stay Numerical; days 
Need for intubation Categorical; N=0, Y=1 
Post procedure hemothorax Categorical; N=0, Y=1 
Post procedure pneumothorax Categorical; N=0, Y=1 
Post procedure pathology requiring 
chest tube  
Categorical; N=0, Y=1 
Surgical site infection Categorical; N=0, Y=1 
Post procedure pneumonia Categorical; N=0, Y=1 
Post procedure DVT Categorical; N=0, Y=1 
Discharge  
 
MME equivalents on day of discharge Numerical 
Gabapentin  Categorical; N=0, Y=1 
Lidocaine patch Categorical; N=0, Y=1 
NSAIDs Categorical; N=0, Y=1 
Acetaminophen Categorical; N=0, Y=1 
Median pain score in last 24 hours Numerical 
Lowest pain score in last 24 hours Numerical 
Highest pain score in last 24 hours Numerical 
Incentive spirometry Numerical; cc 
Cough Categorical; 0 = none, 1 = weak, 2 = moderate, 3 = strong 
Discharge Day MM/DD/YYYY/24HR time 
Discharged to higher level of care than 
arrival? 
Categorical; N=0, Y=1 
Discharged to home Categorical; N=0, Y=1 
Discharged with home health Categorical; N=0, Y=1 
Discharged to SNF Categorical; N=0, Y=1 

 
 
Discharge to LTAC Categorical; N=0, Y=1 
Died in hospital Categorical; N=0, Y=1 
Follow up data 
 
Day of follow up MM/DD/YYYY/24HR time 
Daily MME usage Numerical 
Gabapentin use  Categorical; N=0, Y=1 
Lidocaine patch Categorical; N=0, Y=1 
NSAIDs Categorical; N=0, Y=1 
Acetaminophen Categorical; N=0, Y=1 
McGill Pain Score Numerical 
Sensory: X/33 
Affective: X/12 
Visual Analogue Scale: X/10 
Present Pain Intensity: X/10 
Glasgow Outcome Scale Categorical; D = 0, VS = 1, SD- = 2, SD+ = 3, MD- = 4, MD+ = 5, 
GR- = 6, GR+ = 7 
SF-12 PCS score Numerical  
SF-12 MCS score Numerical 
Incentive spirometry Numerical; cc 
Cough Categorical; 0 = none, 1 = weak, 2 = moderate, 3 = strong 
Winged scapula Categorical; N=0, Y=1 
Readmitted since last seen Categorical; N=0, Y=1 
Rib-specific admission? Categorical; N=0, Y=1 
Currently living at home  Categorical; N=0, Y=1 
Currently living at home with assistance Categorical; N=0, Y=1 
Currently living at SNF Categorical; N=0, Y=1 
Currently living at LTAC Categorical; N=0, Y=1 
Died Categorical; N=0, Y=1 
Date of death MM/DD/YYYY/24HR time 
* will use a (.) for missing variables 
 
Analysis Plan: 
All statistical analysis will be performed with STATA. A single interim analysis will be performed at 50% 
enrollment. Analyses will be performed on both the intention-to-treat study population (which includes all 
enrolled participants, regardless of whether or not they received the treatment) as well as the per protocol 
analysis population (including only participants who actually received the treatment). Numerical variables will 
be expressed as mean (standard deviation) when normally distributed, and as median (interquartile range) 
when skewed. Categorical variables will be expressed as frequencies and percentages. Normal distribution will 
be assessed by the Kolmogorov-Smirnov test and visual inspection of histograms. Numerical values and 
categorical variables will be compared with the Mann-Whitney test and Fisher exact test respectively. Non-
normally distributed data will undergo Box-Cox transformation. Any demographic or hospitalization variable 
with a P <0.1 on univariate analysis will be included in the multivariate model. A p-value of <0.5 is considered 
significant. 
 
Database Protection: Participants are labelled with REDCap assigned participant IDs. Names, medical record 
numbers and ALL dates (dates of birth, admission, surgery and discharge) are removed from the REDCap 
database. Other HIPPA identifiers such as medication use and diagnostic results are present in the REDCap 
database for us to be able to evaluate the rib fracture in context of which treatment group the patient is 
assigned to. The REDCap database itself is a secure, password-protected database that is housed on 
Stanford servers. Furthermore only 3 members of the study team (Protocol Director and Data Administrator) 
have access to the code that can be used to indirectly link back to identifiers 
 
Patient Safety: 

 
 
 
The Protocol Director will be responsible for Data Safety and Monitoring for this study. The Protocol Director is 
a board-certified trauma and critical care surgeon with fellowship training in epidemiology. Adverse events 
including bleeding from injury to an intercostal artery, injury to an intercostal nerve, pneumothorax, neuroma, 
procedure site infection will be reviewed. Protocol deviations will be reviewed. At 50% enrollment, and interim 
analysis will be performed and reviewed for harm. The protocol director will report all Serious Adverse Events 
(SAEs), Suspected Unexpected Serious Adverse Reactions (SUSARs), or Unanticipated Problems (UPs) to 
the IRB in accordance with FDA regulations. The Protocol Director will review any SAEs, SUSAR, or UP with 
the IRB. The Protocol Director will provide all interim data to the IRB for evaluation and approval. The study will 
end after 110 patients have been accrued, if the study is recommended to be stopped at interim analysis, or at 
the discretion of the IRB. The Protocol Director will disseminate outcomes of the review to the IRB and the 
protocol director.  
 

 
 
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