Proof-of-Concept: A Device to Determine Return of Sensation After a Regional Anesthetic Block
Phase: NA
Conditions: Sensation Diminished, Pinprick
Sponsor: Wake Forest University Health Sciences

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Protocol version: 10/13/20 
 
 
NCT:  NCT04553913 
DATE:  10/13/20 
 
Study Title:  Proof-of-Concept: A Device to Determine Return of Sensation After a 
Regional Anesthetic Block. 
 
Principal Investigator, Co-investigator(s):  Seiha Kim DO; Wessley McKnight, MD; Robert 
S. Weller MD 
 
Sponsor or funding source: Department of Anesthesiology, Wake Forest School of Medicine 
 
 
Background, Rationale and Context 
 
Regional anesthesia investigators have always shown interest in measuring the specific 
duration of neuraxial or peripheral nerve blocks, and how variations in block technique or 
medications affect that duration.  Although ostensibly a simple concept, there are many 
sensory modalities available for block testing (light touch, cold or hot temperature, pain, 
pressure, etc.) and there is no consensus in the anesthesia literature on how best to 
measure the duration of nerve block (1).  Sensory testing is repetitive, and must be 
practical and consistent.  Pinprick and cold sensation are commonly employed, and these 
modalities share the same afferent fibers (C-delta) so there is close overlap in the sensory 
loss mapping after regional block (2).  With respect to pinprick sensation (3, 4) there can 
be variability in the sharpness, pressure, and reproducibility of a pinprick test.  Testing 
for cold sensation may be more consistent, using a controlled stimulus temperature and 
duration, and there are different methods of testing such as a cooled glass vial (4) (5℃) or 
Rolltemp (5) (25℃).  
Cold therapy is a commonly applied modality following strenuous exercise or during 
recovery from extremity surgery, and is expected to reduce tissue damage and relieve 
pain.  There is some evidence of benefit but little consensus on the optimum interval and 
duration of therapy (6), and there are many approved medical devices available for use.    
This investigation proposes an adaptation of an approved cold therapy device to 
administer automated, periodic cold stimuli at a location made insensate by regional 
block.  When the patient perceives cold at that site, they will press a stop switch to 
discontinue cooling which will also stop a timer and give an accurate duration of the time 
to sensory recovery at that site.   
The concept will be tested by comparing the duration measured by this device to the 
standard measurement of recovery from spinal block employed by post-anesthesia care 
unit (PACU) nurses who will use pinprick (toothpick) testing of lumbar dermatomes 
every thirty minutes.    
 
Objectives 
 

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Protocol version: 10/13/20 
 
 
Main objective:  To test the agreement of standard pinprick (toothpick) sensory recovery 
testing after spinal anesthesia with the duration of sensory block as determined by the 
modified device. 
 
 
 
.  
 
 
Methods and Measures 
 
Design 
 
This is an observational series to determine the agreement of an experimental application 
of an approved medical device designed to test recovery of sensation from spinal 
anesthesia, with the customary clinical method of testing recovery from spinal anesthesia. 
 
Subjects selection criteria 
 
• Inclusion Criteria 
o Patients 18-75 y/o and scheduled to undergo unilateral primary knee or hip 
arthroplasty under spinal anesthesia with bupivacaine, ropivacaine or 
tetracaine will be eligible  The study will be conducted at Wake Forest 
Baptist Hospital and Davie Medical Center 
• .Exclusion Criteria 
o Exclusions to cold therapy due to medical disease such as Raynaud’s 
disease, Buerger’s  disease, sickle cell disease, significant peripheral 
vascular disease (history of limb vascular stents or bypass), 
hypercoagulable clotting disorders, cold agglutinin disease, history of 
frostbite of the legs, and neuropathy in the lumbar dermatomes under 
investigation. 
o Subjects will be excluded if pre-block sensation is abnormal in the L3 
dermatome of the non-operative leg , or if spinal anesthesia is not 
performed or is unsuccessful.    
o Subjects will be excluded if sensation has already returned in the L3 
dermatome of the non-operative leg upon arrival to the PACU.   
• Sample Size 
• Sample size calculations (see analysis below) predict 9 subjects will be 
sufficient to show equivalence. We will recruit 15 subjects for the study to 
account for drop-out after enrollment. 
 
Interventions and Interactions 
 
Subjects will be recruited before their surgical date in one of two ways.  They may be 
approached at the conclusion of their preoperative assessment clinic (PAC) appointment to 

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review the study and provide written consent if willing to participate.  If not approached at the 
PAC visit, they may be contacted by phone prior to the surgical date using a telephone script to 
introduce the study, review exclusion criteria and determine interest.  If interested, subjects will 
have questions answered and later complete a written informed consent in the preoperative 
holding area on the day of surgery.  The subject’s ability to perceive cold (ice) and pain 
(toothpick) will be assessed in the L3 dermatome on the non-operative thigh, and they will be 
excluded if pre-block sensation is abnormal in the L3 dermatome, They will also be excluded if 
decision to use general rather than spinal anesthesia is chosen at this time.  If eligibility is 
confirmed, a skin location on the non-operative thigh will be marked with a circled “X” using 
marking pen after this assessment to show the location for the device pad to be applied in PACU.  
Subjects will be shown the cooling device and instructed on how and when to press the “stop” 
button when they feel cold at the application site.   
The patient will then undergo usual anesthesia care with preoperative analgesic and sedative 
medications, peripheral blocks if indicated, spinal anesthesia and intraoperative sedation.  The 
time of spinal injection and medication and dose will be recorded.  Subjects will be excluded at 
this point if spinal anesthesia is unsuccessful. 
After surgery and upon arrival in PACU, if the subject has already recovered sensation at the L3 
dermatome (at the “X”), they will be excluded from the study at that time.  If they have not 
recovered sensation, the device pad will be wrapped to the non-operative thigh at the “X” 
location by a study team member, and an elastic bandage used to secure the cooling pad to the 
patient.  Cycling will begin with 15 min of cold circulation, then 15 minutes off.  A PACU nurse 
who is not aware of the cooling pump activity will test the patient in the lumbar dermatomes (L1 
to L4) every 30 minutes per usual practice (the L3 dermatome will be tested adjacent to the 
cooling pad).  The most cephalad level of prick sensation with toothpick stimulus will be 
recorded on the PACU flowsheet in WakeOne.  Cooling pad temperature during pump cycling  
will be measured with a wireless sensor, and expected to reach approximately 40-50 degrees 
Fahrenheit when cooling (based on in vitro testing), and return toward body temperature when 
not cooling; the range will be recorded on the data sheet. Usual PACU discharge criteria will be 
employed, but it is expected the testing will end when regression of spinal block to L3 is 
achieved. Study participation will continue until the subject stops the pump cycling, and is 
expected to continue up to 4 hours.   
 
Outcome Measure(s) 
 
 
• 
Primary Outcome Measure  
Block Recovery Time:  Time to resolution of spinal anesthetic (minutes from injection) 
will be measured in minutes for (i) the device and (ii) standard nursing pinprick testing 
on the same (non-operative) thigh. 
 
 
 

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Protocol version: 10/13/20 
 
 
Analytical Plan 
 
Time to resolution of spinal anesthetic will be measured in minutes for (i) our device and (ii) 
standard nursing pinprick testing on the same (non-operative) thigh.  We will test the 
equivalence of (i) and (ii), where the equivalence region is defined as the difference in (i) and (ii) 
falling in the interval [-29, 29] minutes.  In the sample size calculation, it is assumed that time to 
spinal resolution has a mean of 140 minutes (standard deviation 29 minutes) such that we are 
targeting an equivalence region of [-1, 1] standardized units.  With type 1 error set to 0.05, we 
need 9 pairs of observations to achieve 80% power.  Calculations were performed using the R 
package ‘TOSTER ’.   
To test equivalence of the measurements in real data, the same procedure of “two one-sided 
tests” will be employed, with t-tests of the one-sided hypotheses that the null difference is less 
than -29 minutes or that the null difference is greater than 29 minutes.  
 
Human Subjects Protection 
 
Subject Recruitment Methods 
 
Study team members (Anesthesiology Faculty) will be providing the anesthesia care for patients 
undergoing hip and knee arthroplasty and routinely review clinical information in the days 
before surgery to prepare for this care.   They will identify eligible patients as a part of this 
review and let the clinical research staff know of potential subject recruitment.   Patients meeting 
eligibility requirements will be recruited before their surgical date in one of two ways.  They 
may be approached at the conclusion of their preoperative assessment clinic (PAC) appointment 
to review the study and consent form.  If not approached at the PAC visit, they may be contacted 
by phone prior to the surgical date as described above in “interactions” using a telephone script 
to introduce the study, review exclusion criteria and determine interest.  If interested, patients 
will have questions answered and later complete a written informed consent in the preoperative 
holding area on the day of surgery.  Patients will NOT be recruited on the day of surgery if they 
have not already been contacted by phone or seen in person prior to their day of surgery.  
 
 
Informed Consent 
 
Signed informed consent will be obtained from each subject.   
 
Confidentiality and Privacy 
 
Confidentiality will be protected by collecting only information needed to assess study 
outcomes, minimizing to the fullest extent possible the collection of any information that could 
directly identify subjects, and maintaining all study information in a secure manner.  To help 
ensure subject privacy and confidentiality, only a unique study identifier will appear on the data 
collection form.  Any collected patient identifying information corresponding to the unique study 
identifier will be maintained on a linkage file, store separately from the data.  The linkage file 
will be kept secure, with access limited to designated study personnel.  Following data collection 

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subject identifying information will be destroyed by shredding 3 years after study completion 
consistent with data validation and study design, producing an anonymous analytical data set.  
Data access will be limited to study staff.  Data and records will be kept locked and secured, with 
any computer data password protected.  No reference to any individual participant will appear in 
reports, presentations, or publications that may arise from the study. 
 
Data and Safety Monitoring 
The principal investigator will be responsible for the overall monitoring of the data and safety of 
study participants.  The principal investigator will be assisted by other members of the study 
staff. 
 
Reporting of Unanticipated Problems, Adverse Events or Deviations 
 
Any unanticipated problems, serious and unexpected adverse events, deviations or protocol 
changes will be promptly reported by the principal investigator or designated member of the 
research team to the IRB and sponsor or appropriate government agency if appropriate. 
 
References 
 
1. Ode K., et al   Monitoring regional blockade. Anaesthesia 2017, 72 (Suppl. 1), 70–75 
2. M. Nersesjan , et al  Sensory distribution of the lateral femoral cutaneous nerve block – a 
randomised, blinded trial   Acta Anaesthesiologica Scandinavica 62 (2018) 863–873 
3.  Turner JD, et al. Single-Injection Adductor Canal Block With Multiple Adjuvants 
Provides Equivalent Analgesia When Compared With Continuous Adductor Canal 
Blockade for Primary Total Knee Arthroplasty: A Double-Blinded, Randomized, 
Controlled, Equivalency Trial.   J Arthroplasty. 2018 Oct; 33(10): 3160-3166. 
4. Nader A, et al. A dose-ranging study of 0.5% bupivacaine or ropivacaine on the success 
and duration of the ultrasound-guided, nerve-stimulator-assisted sciatic nerve block: a 
double-blind, randomized clinical trial.   Reg Anesth Pain Med. 2013 Nov-Dec; 38(6): 
492-502. 
5. Madsen MH, et al. Local Anesthetic Injection Speed and Common Peroneal Nerve Block 
Duration: A Randomized Controlled Trial in Healthy Volunteers  Reg Anesth Pain Med. 
2018 Jul; 43(5): 467-473. 
6. Bleakley C, et al  The Use of Ice in the Treatment of Acute Soft-Tissue Injury  A 
Systematic Review of Randomized Controlled Trials.  The American Journal of Sports 
Medicine, 2004: 32(1):251-261 
 
 
Appendix 
1. Data collection form 

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2. Consent form  
3. Device information, modification, clinical engineering testing 
4. Telephone “script”