Interscalene Block Versus Superior Trunk Block: A Randomized Controlled Clinical Trial
Phase: PHASE4
Conditions: Joint Disease, Pain, Pain, Acute, Pain, Chronic
Sponsor: Hospital for Special Surgery, New York

 
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Interscalene Block versus Superior Trunk Block: A 
Randomized Controlled Clinical 
Trial 
FUNDER: 
Research & Education Fund, Department of 
Anesthesiology, Critical Care & Pain 
Management 
PROTOCOL NO.: 
IRB#2017-0979 
VERSION & DATE: 
12/3/19 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
 
 
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PROTOCOL SYNOPSIS 
Protocol Title: 
Interscalene Block versus Superior Trunk Block: A Randomized 
Controlled Clinical Trial 
Protocol Number: 
2017-0979 
Protocol Date: 
7/3/2019 
Sponsor: 
N/A 
Principal 
Investigator: 
David Kim, MD 
Products: 
N/A 
Objective: 
Sparing the phrenic nerve by administering ultrasound-guided 
low volume superior trunk block (STB) and interscalene block 
(ISB) for arthroscopic shoulder surgery.  
Study Design: 
Randomized Controlled Trial 
Enrollment: 
126 total 
Subject Criteria: 
 
Patients who will be undergoing arthroscopic primary 
unilateral labral repair/stabilization of the shoulder, 
arthroscopic shoulder rotator cuff repair, and 
arthroscopic shoulder 
 
capsular release, labral debridement, and bankart repair 
 
Age 18 to 80 years 
 
Planned use of general anesthesia and interscalene or 
superior trunk block 
 
Ability to follow study protocol 
 
English speaking 
 
ASA I - III 
Study Duration: 
 
9/2017- 8/2018 
Data Collection: 
 
Demographics 
 
Respiratory Parameters (MV, RR, TV) 
 
Diaphragm Analysis 
 
Patient Satisfaction 
 
Incidence of Adverse Effects (horner’s/hoarness, 
dyspnea, hiccups, coughing)  
 
Pulm Function (NIF, FEV1, FVC) 
 
Sensory Exam 
 
Handgrip 
 
NRS pain scores at rest, at movement 
 
Opioid Consupmtion 
 
Neuropraxia 

 
 
 
 
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 
Nerve Block Success 
 
Length of PACU stay 
 
Blinding assessment 
 
Time to meet discharge criteria 
Outcome 
Parameters: 
1. Our primary outcome will be the incidence of 
hemidiaphragmatic paralysis (HDP) with superior trunk 
block and interscalene blocks as measured by 
ultrasound before and after the surgery as well as NRS 
Pain scores at rest in the PACU measured after the 
surgery every 30 minutes where worst pain in PACU will 
be the highest recorded number during PACU stay. 
2. Full resolution of the block will be reported by the patient 
on POD 1via RA phone call 
3. Handgrip as measured by dyanamometer. Maximum grip 
strength will be assessed pre op and upon 60 min after 
PACU arrival (2 measurements will be done per time 
point and the average will be recorded) 
4. Change in respiratory function as measured by changes 
in average minute ventilation, respiratory rate and tidal 
volume from preoperative baseline using a non-invasive 
monitoring device, and by changes in forced maneuvers: 
NIF, FEV1 and FVC measured preoperatively in holding 
area and 60 minutes postoperatively in the PACU. 
5. incidence of ISB related side effects: horner’s syndrome, 
hoarseness, hiccups, coughing, dyspnea in PACU 
6. Time to readiness for PACU discharge (time of PACU 
admission to time of readiness to discharge, measured 
by Post Anesthetic Discharge Scoring System) evaluated 
every 15minutes. 
7. Block duration 
8. Incidence of paresthesia / neuropraxia (POD1, POD ): 
persistent tingling, numbness in POD1, if patient reports 
persistent neuropraxia after POD2, will follow up on 
POD7. If persists, will notify attending anesthesiologist 
and continue to follow until postoperative neurologic 
symptoms (PONS) resolves. 
9. NRS Pain Scores at rest and with movement (PACU, 
POD 1, POD2) 
10. Opioid consumption (PACU, POD1, POD2) 
 
Statistical Analysis: 
Proposed analysis (e.g., student’s t-test, ANOVA, chi-square, 
regression, etc.): Non-inferiority and superiority tests 
2. Alpha level: 0.025 
3. Beta or power level: 80% 

 
 
 
 
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4. Primary outcome variable estimate (mean +/- s.d. for 
continuous outcome, frequency/percentage for categorical 
variable): Two primary outcomes for join 
hypothesis: 
1 – Incidence of HDP: 76% vs. 40.6%; appx. 35% clinically 
meaningful difference (Dimeo, unpublished) – used for 
superiority hypothesis 
2 – NRS worst pain in PACU: 1.6 points non-inferiority margin 
(Kim (2014) citing Ilfeld (2011)), 2.9 within-group SD (Kahn, 
unpublished) – used for non-inferiority hypothesis(See 
below) 
5. Number of groups being compared (use 1 for paired analysis 
within the same subjects): 2 
6. Effect size or change expected between groups: 
See below 
7. Resulting number per group: 52 
8. Total sample size required: 104 + 20% to account for 
attrition/withdrawal -->126 
9. Who conducted your sample size calculation? Sarah 
Weinstein and Yan Ma (Conducted prior analysis for Dr. Stavros 
Memtsoudis ISB vs SCP study) 
 
Primary outcomes: 
The incidence of HDP between two groups will be compared 
using chi-square/Fisher’s exact test. Logistic regression analysis 
may be performed to compare the incidence of HDP between 
the two blocks while adjusting potential confounders. 
NRS worst pain scores in PACU will be compared between the 
two groups using the Mann-Whitney-Wilcoxon U test or two-
sample t-tests (depending on the distribution of the data). 
Secondary outcomes: 
Continuous secondary outcomes measured at one time point 
(e.g., PACU length of stay, etc.) will be compared between the 
STB and ISB groups using t-test / Mann Whitney 
Wilcoxon rank test (depending on data distribution) 
Categorical secondary outcomes measured at one time point 
will be compared between the STB and ISB groups using chi-
square/Fisher’s exact test (depending on data distribution). 
Continuous and categorical outcomes measured at multiple time 
points (e.g., opioid consumption, change in respiratory 
consumption, patient satisfaction, etc.) will be analyzed using a 
generalized estimating equations (GEE) approach. 
Baseline characteristics: 

 
 
 
 
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Demographics and other baseline characteristics will be 
compared between the STB and ISB groups. Balance 
diagnostics, such as described in Austin 2009 [1] may be used 
for assessing similarity of baseline characteristics between the 
two study groups. 
 
 
 

 
 
 
 
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1.0 INTRODUCTION 
Peripheral nerve blocks (PNBs) have been the mainstay analgesic for ambulatory shoulder 
arthroscopies. PNB’s provide both surgical anesthesia and postoperative analgesia. 
The interscalene block (ISB) remains the gold standard for shoulder arthroscopic surgeries. 
However, it is not without untoward effects, mainly the blockade of the phrenic nerve 
(diaphragmic hemiparesis), sympathetic nerves (horner’s syndrome), and recurrent laryngeal 
nerve (hoarseness). A study done at HSS has revealed the incidence of phrenic nerve paresis 
to be 76% with an ISB in comparison to 40.6% with a supraclavicular block using 45 ml of 0.5% 
bupivacaine (Dimeo et.al. not published). 
Ultrasound has allowed for the refinement of peripheral nerve blocks. Under ultrasound 
guidance, regional blocks can be performed with pinpoint accuracy, enabling the practitioner 
to target only the nerves that supply the area needed for the surgery and sparing nerves that 
would normally be blocked. The adductor canal block is an example of such refinement, where 
the femoral nerve and its motor blockade of the quadriceps are spared with the ACB. Another 
such refinement of the interscalene block is the superior trunk block (STB), isolating the 
bundle of nerves that would provide anesthesia and analgesia for the shoulder joint, sparing 
the phrenic nerve, recurrent laryngeal nerve and a portion of brachial plexus enabling patient 
to hand grip. 
Low-volume targeted PNB’s like the superior trunk block theoretically should lead to a lower 
incidence of phrenic nerve paresis but the literature is lacking in examining this and also its 
implication of sparing respiratory function. This study would help elucidate the question of 
whether the STB spares the phrenic nerve, and provide adequate analgesia. 
2.0 PRODUCT DESCRIPTION 
N/A 
3.0 OBJECTIVE OF CLINICAL STUDY 
1. Does the Superior trunk block spare the phrenic nerve more often than the ISB? 
2. Does the Superior trunk block provide as adequate analgesia as an ISB for 
shoulder arthroscopy? 
3. Does the Superior trunk block spare motor blockade of the hand? 
4. Does the Superior trunk block spare the recurrent laryngeal nerve, preventing 
hoarseness more often than the ISB? 
4.0 STUDY HYPOTHESES 
1. The superior trunk block spares the phrenic nerve more often than the ISB. 
2. Forced respiratory manuevers (negative inspiratory force (NIF), FEV1, and FVC) 
will be spared with the STB in comparison to the ISB. 
3. STB will be noninferior to the ISB with respect to worst NRS pain score at rest in 
the PACU 
 

 
 
 
 
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5.0 STUDY DESIGN 
 
5.1 
Study Duration 
9/2017 – 8/2018 
5.2 
Endpoints 
 
5.2.1 
Primary Endpoint 
 
Our primary outcome will be the incidence of hemidiaphragmatic paralysis 
(HDP) with superior trunk block and interscalene blocks as measured by 
ultrasound before and after the surgery as well as NRS Pain scores at rest in 
the PACU measured after the surgery every 30 minutes where worst pain in 
PACU will be the highest recorded number during PACU stay. 
5.2.2 
Secondary Endpoints 
 
Full resolution of the block will be reported by the patient on POD 1via RA 
phone call 
 
Handgrip as measured by dyanamometer. Maximum grip strength will be 
assessed pre op and upon 60 min after PACU arrival (2 measurements will 
be done per time point and the average will be recorded) 
 
Change in respiratory function as measured by changes in average minute 
ventilation, respiratory rate and tidal volume from preoperative baseline using 
a non-invasive monitoring device, and by changes in forced maneuvers: NIF, 
FEV1 and FVC measured preoperatively in holding area and 60 minutes 
postoperatively in the PACU. 
 
incidence of ISB related side effects: horner’s syndrome, hoarseness, 
hiccups, coughing, dyspnea in PACU 
 
Time to readiness for PACU discharge (time of PACU admission to time of 
readiness to discharge, measured by Post Anesthetic Discharge Scoring 
System) evaluated every 15minutes. 
 
Block duration 
 
Incidence of paresthesia / neuropraxia ( POD1, POD ): persistent tingling, 
numbness in POD1, if patient reports persistent neuropraxia after POD2, will 
follow up on POD7. If persists, will notify attending anesthesiologist and 
continue to follow until postoperative neurologic symptoms (PONS) resolves. 
 
NRS Pain Scores at rest and with movement (PACU, POD 1, POD2) 
 
Opioid consumption (PACU, POD1, POD2) 
 
5.3 
Study Sites 
Hospital for Special Surgery Main Hospital – Ambulatory Surgery  

 
 
 
 
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6.0 STUDY POPULATION 
6.1 
Number of Subjects 
 
126 subjects  
 
6.2 
Inclusion Criteria 
Subjects of either gender will be included if they: 
 
1. Patients who will be undergoing arthroscopic primary unilateral labral 
repair/stabilization of the shoulder, arthroscopic shoulder rotator cuff repair, 
and arthroscopic shoulder 
2. capsular release, labral debridement, and bankart repair 
3. Age 18 to 80 years 
4. Planned use of general anesthesia and interscalene or superior trunk block 
5. Ability to follow study protocol 
6. English speaking 
7. ASA I - III 
6.3 
Exclusion Criteria 
Subjects will be excluded from the study if they: 
 
1. Pre-existing neuropathy of the operative limb 
2. Younger than 18 years old and older than 80 
3. Patients with severe respiratory disease 
4. Allergy to one of the study medications 
5. Chronic gabapentin/pregabalin use (regular use for longer than 3 months) 
6. Chronic opioid use (taking opioids for longer than 3 months) 
7. Contraindication to general anesthesia, interscalene or superior trunk block 
8. Herniated Cervical Disk, Cervical Myelopathy 
9. BMI >35 
10. Non English speakers 
6.4 
Randomization 
  
 The randomization will occur upon IRB approval and prior to start of study enrollment. 
Randomization will be revealed to the anesthesiologist after the patient gives consent 
in the holding area prior to surgery. After consent is obtained, the anesthesiologist will 
be given a sealed opaque envelope corresponding to the patients study ID number 
and randomization to either treatment or control. The envelope will be opened in the 
operating room, not in the presence of the investigators that assess the patients post-
operatively 

 
 
 
 
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7.0 PROCEDURES 
7.1 
Surgical Procedure 
Arthroscopic shoulder surgery  
 
7.2 
Data Collection 
 
Our primary outcome will be the incidence of hemidiaphragmatic paralysis 
(HDP) with superior trunk block and interscalene blocks as measured by 
ultrasound before and after the surgery as well as NRS Pain scores at rest in 
the PACU measured after the surgery every 30 minutes where worst pain in 
PACU will be the highest recorded number during PACU stay. 
 
Full resolution of the block will be reported by the patient on POD 1via RA 
phone call 
 
Handgrip as measured by dyanamometer. Maximum grip strength will be 
assessed pre op and upon 60 min after PACU arrival (2 measurements will 
be done per time point and the average will be recorded) 
 
Change in respiratory function as measured by changes in average minute 
ventilation, respiratory rate and tidal volume from preoperative baseline using 
a non-invasive monitoring device, and by changes in forced maneuvers: NIF, 
FEV1 and FVC measured preoperatively in holding area and 60 minutes 
postoperatively in the PACU. 
 
incidence of ISB related side effects: horner’s syndrome, hoarseness, 
hiccups, coughing, dyspnea in PACU 
 
Time to readiness for PACU discharge (time of PACU admission to time of 
readiness to discharge, measured by Post Anesthetic Discharge Scoring 
System) evaluated every 15minutes. 
 
Block duration 
 
Incidence of paresthesia / neuropraxia ( POD1, POD ): persistent tingling, 
numbness in POD1, if patient reports persistent neuropraxia after POD2, will 
follow up on POD7. If persists, will notify attending anesthesiologist and 
continue to follow until postoperative neurologic symptoms (PONS) resolves. 
 
NRS Pain Scores at rest and with movement (PACU, POD 1, POD2) 
 
Opioid consumption (PACU, POD1, POD2)

 
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7.3 
Schedule of Assessments 
Study Visit 
# 
Surveys / 
Questionnaires 
Randomization 
Arthroscopic 
Shoulder 
Surgery 
Ultrasound/Handgrip 
measurement/ 
Pulmonary Function 
Assessment 
Pre-op 
Holding 
Area 
X 
X 
 
X 
Surgery 
 
 
SOC 
X 
Post 
Anesthesia 
Care Unit 
X 
 
 
X 
POD 1 
X 
 
 
 
POD 2 
X 
 
 
 
 
X=  Research procedures 
SOC= Standard of care (care you would receive if you were not participating in this study) 

 
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8.0 STATISTICAL ANALYSIS 
1. Proposed analysis (e.g., student’s t-test, ANOVA, chi-square, regression, etc.): Non-
inferiority and superiority tests 
2. Alpha level: 0.025 
3. Beta or power level: 80% 
4. Primary outcome variable estimate (mean +/- s.d. for continuous outcome, 
frequency/percentage for categorical variable): Two primary outcomes for join 
hypothesis: 
1 – Incidence of HDP: 76% vs. 40.6%; appx. 35% clinically meaningful difference (Dimeo, 
unpublished) – used for superiority hypothesis 
2 – NRS worst pain in PACU: 1.6 points non-inferiority margin (Kim (2014) citing Ilfeld 
(2011)), 2.9 within-group SD (Kahn, unpublished) – used for non-inferiority hypothesis (See 
below) 
5. Number of groups being compared (use 1 for paired analysis within the same subjects): 2 
6. Effect size or change expected between groups: 
See below 
7. Resulting number per group: 52 
8. Total sample size required: 104 + 20% to account for attrition/withdrawal -->126 
9. Who conducted your sample size calculation? Sarah Weinstein and Yan Ma (Conducted 
prior analysis for Dr. Stavros Memtsoudis ISB vs SCP study) 
 
Primary outcomes: 
The incidence of HDP between two groups will be compared using chi-square/Fisher’s exact 
test. Logistic regression analysis may be performed to compare the incidence of HDP 
between the two blocks while adjusting potential confounders. 
 
NRS worst pain scores in PACU will be compared between the two groups using the Mann-
Whitney-Wilcoxon U test or two-sample t-tests (depending on the distribution of the data). 
 
Secondary outcomes: 
Continuous secondary outcomes measured at one time point (e.g., PACU length of stay, 
etc.) will be compared between the STB and ISB groups using t-test / Mann Whitney 
Wilcoxon rank test (depending on data distribution) 
 
Categorical secondary outcomes measured at one time point will be compared between the 
STB and ISB groups using chi-square/Fisher’s exact test (depending on data distribution). 
Continuous and categorical outcomes measured at multiple time points (e.g., opioid 
consumption, change in respiratory consumption, patient satisfaction, etc.) will be analyzed 
using a generalized estimating equations (GEE) approach. 
 
 
 

 
 
 
 
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Baseline characteristics: 
Demographics and other baseline characteristics will be compared between the STB and 
ISB groups. Balance diagnostics, such as described in Austin 2009 [1] may be used for 
assessing similarity of baseline characteristics between the two study groups. 
 
9.0 ADVERSE EVENT ASSESSMENT 
All Adverse Events (AEs) will be reported in the final study report. Definitions for Adverse 
Event (AE) used in this study are listed below and are based on FDA and international 
guidelines: 
 
9.1 
Adverse Event (AE) 
Patients will be made aware of the potential risks and study medications before 
enrollment. We will not enroll any patients with a history of adverse reactions to any 
of the study medications or are uncomfortable with study procedures. Once enrolled, 
if there is a physical risk, therapy will be initiated in the hospital, and patients will be 
monitored per standard of care by the hospital staff.  
The anesthetic and surgical methods applied in the study are well documented and 
practiced for Shoulder Arthroscopy. The combination of these methods may increase 
the anticipated benefits by lowering patients' chances of hemidiaphragmatic 
paralysis and its side effects. Further, it may also spare hand grip. As a result, this 
may increase patient satisfaction post surgery. 
9.2 
Serious Adverse Events (SAE) 
If a patient experiences complications, they will be kept at HSS for observation and 
withdrawn from the study. Such complications that would cause safety and toxicity 
concerns include local anesthetic toxicity, cardiac toxicity, and central nervous 
toxicity. 
9.3 
Subsequent Surgical Interventions Definitions 
N/A 
9.4 
Adverse Event Reporting 
The study will be monitored by the study investigators for adverse events. Any 
adverse events will be reported to the Institutional Review Board.  
10.0 INVESTIGATOR RESPONSIBILITIES, RECORD AND REPORTS 
 
10.1 Subject Consent and Information 
Written/signed consent will be collected from participants in the holding area before 
surgery. 
10.2 Subject Data Protection 
• HSS tries to minimize those risks by (i) removing some direct identifiers from information 
stored [(i.e., names, social security numbers, medical record numbers)]; (ii) securing, in a 

 
 
 
 
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separate location, and limiting access to information linking codes (i.e., linkage codes) 
assigned to the registry information with direct participant identifiers; and (iii) limiting 
access to information stored to HSS investigators.  
• Access to the REDCap program is password-protected, and access to a specific study's 
information within the program is limited to the research assistant and other IRB-approved 
study personnel who have been given permission to view and/or enter study data. REDCap 
program access is authorized by the CTSC; particular study access is granted by the 
research assistant. For data exports, fields marked as protected health information (PHI) in 
REDCap will be de-identified, if feasible. 
• All transmission of data will occur via encrypted networks in password-protected files. Any 
paper-based data sheets utilized for the study will have personal identifiers removed 
whenever possible and will be stored in the department's locked office. Each subject will be 
assigned a unique study number for identification, and that number will not be derived from 
or related to information about the individual. Presentations and publications that result from 
this study will not contain any individual identifiers (at most the unique study numbers may 
be referred to). Thus our research presents a minimal risk of harm to subjects' privacy.