Endotracheal Intubation Using Videolaryngoscopy Versus Conventional Direct Laryngoscopy: A Randomized Multiple Cross-over Cluster Trial
Phase: NA
Conditions: Intubation, Laryngoscopy
Sponsor: The Cleveland Clinic

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Endotracheal intubation using videolaryngoscopy versus 
conventional direct laryngoscopy:  
a randomized multiple cross-over cluster trial 
 
Version 7, March 27 2022 
 
 
Primary Investigator: Kurt Ruetzler, MD1,2;  
Departments of Outcomes Research and General Anesthesiology, Anesthesiology 
Institute, Cleveland Clinic, 9500 Euclid Ave — P77, Cleveland, OH 44195. Email: 
ruetzlk@ccf.org, Web: www.OR.org. 
 
Co-Investigators:  
 
John Apostolakis, MD3, 
Sherif Assaad, MD3; 
Andrew Bauer, MD3; 
Sergio Bustamente, MD3;  
Chase Donaldson, MD3;  
Andra Duncan, MD1,3; 
Marta Kelava, MD3, 
Sandeep Khanna, MD1,2,3; 
Erik Kraenzler, MD3, 
Nikhil Kumar, MD3; 
Yasdet Maldonado, MD3; 
Natasha Malackany, MD3; 
Edward J. Mascha, PhD 
Daniel I. Sessler, MD1;  
Nick Skubas, MD3;  
Christopher Troianos, MD3;  
Carlos Trombetta, MD3;  
Alparslan Turan, MD1,2 
Brett Wakefield, MD3, 
 
and colleagues.  
 
1. Department of Outcomes Research, Anesthesiology Institute, Cleveland Clinic 
2. Department of General Anesthesia, Anesthesiology Institute, Cleveland Clinic 
3. Department of Cardiothoracic Anesthesiology, Anesthesiology Institute, Cleveland 
Clinic 
 

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Background: Securing airways is a fundamental priority for anaesthesiologists. Severe 
airway complications are rare, but more than 14 % of the events associated with airway 
management in the operating room led to death or brain damage.1,2 Even when ultimately 
successful, difficult intubation is associated with significant patient morbidity and mortality. 
Although anesthesiologists nearly always ultimately succeed in intubating the trachea, 
multiple intubation attempts are common, occurring in 8% of patients.3 Repeated 
intubation attempts are clearly associated with respiratory and hemodynamic 
complications, including hypoxemia, cardiac arrest, regurgitation, aspiration, and airway 
trauma.4-6  
 
Direct laryngoscopy (DL) remains by far the most common primary method for 
endotracheal intubation. But even in experienced hands, additional tools are sometime 
needed.7-9 Videolaryngoscopes are among the most common alternatives or 
supplements to direct laryngoscopy. The method was introduced about two decades ago 
and has gained wide acceptance because videolaryngoscopes improve glottic 
visualization10-12 which may improve first-pass intubation success rate and reduce 
complications.  
 
While it is clear that videolaryngoscopy improves glottic visualization, it is far less obvious 
that first-pass intubation is more likely than with direct laryngoscopy.10,12 Several studies 
reported that videolaryngoscopy improved vocal cord visualization, but prolonged the time 
required for intubation and increased the number intubation attempts.10,12,13 In a trial with 
ICU patients, videolaryngoscopy not only failed to improve first-attempt intubation 
success, but provoked severe complications including hypoxemia, cardiac arrest, 
cardiovascular collapse, and death.14 In contrast, other trials confirm improved glottis 
visualization and report improved first-pass success without an increase in 
complications.15-17 In a recent Cochrane review of more than 7,000 patients with and 
without difficult airways, videolaryngoscopy was associated with fewer complications 
(e.g., laryngeal or airway trauma, postoperative hoarseness, hypoxia), fewer failed 
intubations, and no increase in the time required for intubation.18 Nonetheless, 

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videolaryngoscopes are still usually considered alternative airway devices rather than an 
initial intubation method.  
 
Whether using videolaryngoscopes as the initial operating room intubation device 
reduces intubation attempts remains unclear. Current literature is based on varying study 
settings including manikins, emergency department patients, intensive care patients, and 
out-of-hospital situations.13,19,20 Provider experience also varied considerably, ranging 
from novice physicians to paramedics to nurse anesthetists to highly skilled anesthesia 
attendings.6,12,20,21 Intubation indications also varied, with reports being restricted to 
cardiopulmonary resuscitation, emergency intubation, anticipated easy intubation, etc. 
Interpretation is further complicated by use of various videolaryngoscope devices, not 
always in the appropriate sizes.11-13,16,19-23 
 
Most previous trials have been based on dubious intermediate markers such as glottic 
visualization or time-to-intubation that may correlate poorly with clinically important 
outcomes. Consequently, current evidence precludes defensible analysis of clinically 
meaningful outcomes in the standard operating room setting. No published studies were 
powered to evaluate the number of intubation attempts, a clearly important outcome. The 
extent to which videolaryngoscopes might facilitate intubation in surgical patients during 
routine clinical practice therefore remains unclear. The question is important because 
videolaryngoscopes are more expensive than conventional direct laryngoscopes. The 
additional cost might be justified — but only if video systems improve intubation success 
and reduce airway trauma.   
 
Specific Aims: 
Primary Aim 1: Assess the effect of using a videolaryngoscope versus direct 
laryngoscope for the initial laryngoscopy on the number of intubation attempts in patients 
having cardiac, thoracic, or vascular surgery. 
Primary Hypothesis 1: Fewer intubation attempts are required when initial laryngoscopy 
is performed with a videolaryngoscope rather than a direct laryngoscope in patients 

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having cardiac, thoracic, or vascular surgery. Any reduction in intubation attempts will be 
considered clinically meaningful. 
Primary Outcome: The number of intubation attempts with the initial laryngoscopy 
instrument. 
 
Secondary Aim 1: Compare intubation failure rates with videolaryngoscopy and 
conventional direct laryngoscopy, with failure defined by the clinician switching to an 
alternative laryngoscopy method. 
Secondary Hypothesis 1: There are fewer intubation failures when laryngoscopy is 
initially attempted with a videolaryngoscope rather than a direct laryngoscope. Any 
reduction in intubation failures will be considered clinically meaningful. 
Secondary Outcome 1: Intubation failure, defined by the clinician switching to an 
alternative laryngoscopy method. 
 
Secondary Aim 2: Compare airway and dental injuries when laryngoscopy is initially 
attempted with a videolaryngoscope rather than a direct laryngoscope. 
 
Secondary Hypothesis 2: A composite of airway and dental injuries is less common 
when laryngoscopy is initially attempted with a videolaryngoscope than with a direct 
laryngoscope. A reduction with a number-needed-to-treat <100 will be considered 
clinically meaningful.  
 
Secondary Outcomes 2: Any dental and/or airway injury, defined as any bleeding or 
apparent injury.  
 
Exploratory Hypothesis 1: Intubation assisted by videolaryngoscope provokes less 
hypertension and tachycardia than direct laryngoscopy. Differences in mean arterial 
pressure >10 mmHg and/or in heart rate of at 10 beats/minute will be considered clinically 
meaningful.  
Exploratory Outcomes 1: Maximum mean arterial pressure and heart rate in the 5 
minutes after intubation.  

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Methods: This research project will be conducted with Cleveland Clinic IRB approval and 
waived patients consent. (see Human Subjects section for justification). The trial will be 
registered at ClinicalTrials.gov (NCT04701762, date of registration January 8 2021) 
before enrolling any patients. A full statistical analysis plan will be developed before any 
data are evaluated. Reporting will be consistent with the CONSORT guidelines for pilot 
trials.  
 
Design: The proposed quality improvement project will be conducted in an isolated set 
of 22 operating rooms (J operating suites) at the Cleveland Clinic Main Campus which is 
largely staffed by a consistent team of anesthesia attendings, nurse anesthetists and 
anesthesia residents and fellows with variable level of experience. Most operations in this 
suite are cardiac, thoracic, or vascular surgeries. Nearly all require general anesthesia, 
and most patients are hospitalized at least overnight. 
 
We plan a cluster randomized multiple crossover quality improvement project. The J 
operating suites will be divided into 2 separate clusters consisting of 11 operating suites 
each (cluster 1: operating suites 60 to 70, and cluster 2: operating suites 71 to 81).   
Clusters were formed by physical proximity to make it as logistically feasible as possible 
to conduct the trial. 
 
Randomization will consist of randomizing cluster 1 to use either videolaryngoscope or 
direct laryngoscope, and cluster 2 to the alternative device in one-week blocks.  
 
Randomization, 1:1 and unstratified, will be based on computer-generated codes 
maintained in a web-based system that investigators will access one day before each 
new treatment block begins. Randomization allocations will be verbally communicated to 
anesthesia personnel directly and by signs prominently displayed on each anesthesia 
machine. In previous similar trials, compliance with designated allocations exceeded 
97%.  
 

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Design notes:  Cluster randomized multiple crossover cluster trials are analogous to 
individual patient crossover trials, except that each cluster is crossed over to the other 
treatment in the next period instead of individual patients crossing over. They differ from 
cluster randomized trials (CRT) in that each cluster receives each treatment multiple 
times instead of each cluster only receiving one of the interventions during the trial. 
 
Subject selection: We propose to enroll adults scheduled for elective or emergent 
cardiac, thoracic, or vascular surgery in the designated operating room suite who require 
endotracheal intubation for general anesthesia. We will enroll male and female patients 
of any race and ethnicity. Using the videolaryngoscope as the first line airway device is 
likely to be beneficial and unlikely to augment risk. 
 
Inclusion criteria: 
1. Elective or emergent surgery requiring oral endotracheal intubation for general 
anesthesia. 
Exclusion criteria: 
1. The attending anesthesiologist prefers a specific approach for a particular patient; 
2. Awake fiberoptic intubation is clinically indicated; 
3. Insertion of double-lumen tube. 
 
Protocol: There will be no restrictions on anesthesia management, and anesthesia 
providers will be free to use any type of general anesthesia, supplemented by any type 
of regional anesthesia including neuraxial and peripheral nerve blocks. Fluid 
management, type and dosage of anesthesia medications, and postoperative analgesia 
will also be per clinical preference.  
 
Our clinical routine is to intubate patient’s supine on the OR table. Patients will be pre-
medicated with midazolam 0-2 mg IV, as clinically appropriate. Patients will be pre-
oxygenated until the fraction of expired oxygen exceeds 80%. General anesthesia will be 
induced as preferred by the attending anesthesiologist, usually with a combination of 
lidocaine 1 mg/kg, propofol 1-3 mg/kg or etomidate 0.2-0.3 mg/kg, fentanyl 1-3 µg/kg, and 

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succinylcholine 1.5 mg/kg or rocuronium 1.0 mg/kg. Our routine practice is to perform 
endotracheal intubation after confirming adequate muscle relaxation. In qualifying 
patients, initial laryngoscopy will be performed using one of the following methods: 
1. Direct laryngoscopy with an appropriately sized Macintosh or Miller blade (usually 
size 3 or 4); 
2. Indirect laryngoscopy using a GlideScope videolaryngoscope with an appropriately 
sized blade (usually size 3 or 4). The GlideScope (Verathon, Bothell, WA 98011) 
is an FDA-cleared commercially available portable videolaryngoscope.24-30 
 
Intubations will be performed with a regular endotracheal tube selected by the responsible 
clinician, usually having an internal diameter of 7-8 mm. Endotracheal tubes can be 
equipped with a stylette, per clinical preference. The GlideScope or the Macintosh/Miller 
blade will be introduced into oral cavity according to manufacturer recommendations and 
routine practice. Minor airway manipulation procedures including BURP or Sellick 
maneuvers will be allowed to improve visualization of the vocal cords.  
 
If the initial intubation attempt fails, the endotracheal tube will be removed. Adjustments 
of patient’s position and/or tube stylette are allowed as clinically appropriate. There is no 
limitation regarding intubation attempts, but our routine is to switch to an alternate 
intubation technique after a maximum of 3 failed attempts. Further airway management 
will follow clinical assessment by the attending anesthesiologist. Anesthesiologist will be 
permitted to switch to an alternative method at any time.  
 
Once the trachea is intubated, the tube will be connected to the anesthesia circuit and 
general anesthesia maintained as clinically indicated. At the end of surgery, patients will 
be transferred to the post anesthesia care unit or intensive care unit. 
 
 
 

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Video recording for teaching purposes: a training video of the intubation procedure 
using the GlideScope videolaryngoscope will be produced. This video will be used for 
training purposes of the clinical personnel involved in this clinical trial only and will not be 
shared with anyone outside CCF. Patients will be entirely de-identified. Separate and 
individual informed consent using the CCF “Photograph, Film or Vocal recording release” 
will be obtained in up to a maximum of three patients.    
 
Measurements: All data will be obtained from electronic anesthesia and hospital records. 
No tests or evaluations will be done specifically for this trial. Preoperative airway 
characteristics and difficulties encountered during anesthetic induction will be recorded 
per routine (table 1). Demographic and morphometric characteristics will be obtained from 
the electronic records including age, sex, race, and body mass index. Type of surgery will 
be characterized from ICD-10 codes using AHRQ Clinical Classifications Software. All 
routine anesthetic variables, including medications, will be recorded by routine by our 
electronic anesthesia record keeping system. We will also capture the level of training of 
the person making the first intubation attempt and the final intubation attempts (if a switch 
of anesthesia providers occurred). 
 
Table 1: 
Preoperative airway characteristics 
Neck- full range of motion 
 
Limited neck extension 
 
Limited neck flexion 
 
Limited neck extension and flexion 
 
Short neck 
 
Short thyromental distance 
 
Small mouth opening 
 
Non-compliant submandibular space 
 
Beard presents 
Difficulties encountered during anesthesia induction 
Anterior larynx 
 
Expected difficulties 
 
Large epiglottis 
 
Large tongue 
 
MAC safe cannula 
 
Poor jaw range of motion 
 
Poor neck range of motion 

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Recessed chin 
 
Sniffing position 
 
Stylette required 
 
Unexpected difficulties 
 
Per our clinical routine, an initial attempt will be defined by insertion of a laryngoscope 
blade and/or endotracheal tube into a patient's mouth. Subsequent attempts will be 
defined by re-insertion of an endotracheal tube, or insertion of the same or a new 
laryngoscope blade. Attempts will be recorded per routine by anesthesia providers in the 
electronic record. 
 
Intubation failure will be defined by the responsible clinician switching to an alternative 
laryngoscopy device for any reason at any time, or by more than 3 intubation attempts. 
 
Airway injury will be defined as any bleeding or apparent injury to the lips, mouth, pharynx, 
vocal cords, or other airway structures recorded by the anesthesia team. 
 
Dental injury will be defined as any apparent injury to the teeth as recorded by the 
anesthesia team. 
 
Limitations and anticipated difficulties: 
The proposed study will be by far the largest randomized trial of airway management. It 
will include patients with a broad range of airway characteristics, only excluding patients 
with airway pathologies so severe that responsible clinicians prefer an initial fiberoptic 
intubation. Our finding should therefore be broadly generalizable to adult surgical 
patients.  
 
This project will be performed in the J operating rooms area of the Cleveland Clinic Main 
Campus. This area includes 22 operating rooms, which is largely staffed by a consistent 
team of anesthesia attendings and nurse anesthetists. We have substantial experience 
with large studies in this surgical area, and have had consistently excellent collaboration 
with the entire anesthesia team, along with the surgeons.  

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We selected the GlideScope videolaryngoscope because it is currently used routinely at 
the Cleveland Clinic and all anesthesia personnel are familiar with the device. Finally, 
GlideScope videolaryngoscopy devices and blades have been donated by the 
manufacturer so there will be no cost to patients or the institution.  
 
Statistical Analysis: 
We will assess the balance of randomized groups (videolaryngoscopy vs. direct 
laryngoscopy) on baseline and demographic characteristics using the absolute 
standardized difference (ASD), defined as the absolute difference in means, mean ranks, 
or proportions divided by the pooled standard deviation. Any characteristics with ASD > 
maximum of 0.10 and 1.96
1
2
1
2
(
)x(
)
n
n
n n
+
 will be considered imbalanced and will be 
adjusted for in the primary and secondary analyses.  
 
All primary and secondary analyses will use the modified intent-to-treat principle, 
including all randomized patients who received any of the study. We will conservatively 
assign all missing outcome values as the highest possible score in the control group 
(direct laryngoscopy) and the lowest possible score in the treatment group (GlideScope 
videolaryngoscopy) for all primary and secondary analyses. Assumptions of statistical 
tests will be assessed using graphical and statistical methods.  
 
For the primary outcome, number of intubation attempts will be calculated as the number 
of attempts with either device, independent of whether or not a patient was crossed over 
to the other device due to failure with the randomized device. The ordinal categories will 
be 1, 2, 3, and > 3 attempts.  We will assess the effect of videolaryngoscopy vs. direct 
laryngoscopy on the number of intubation attempts using a generalized linear mixed 
effects cumulative logit model in which we consider the outcome to be ordinal and 
consider the operating room within cluster as a random effect. In sensitivity analyses we 
will assess the treatment effect using a Wilcoxon-Mann-Whitney test and a proportional 
odds logistic regression model, if the assumption of proportional odds holds. In all 
analyses, we will adjust for variables imbalanced at baseline.   

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For the secondary (binary) outcomes of 1) intubation failure and 2) collapsed composite 
of any airway or dental injury we will assess the effect of videolaryngoscopy vs. direct 
laryngoscopy using a generalized linear mixed effects model in which we consider the 
outcome to be binary and consider the operating room within cluster as a random effect.   
 
For exploratory outcomes of maximum mean arterial pressure and heart rate in the 5 
minutes after intubation we will conduct analogous linear mixed effects models for 
continuous variables (i.e., using identity link). Sensitivity analyses will include simple 
Mann-Whitney or t-test, as appropriate.   As with the primary analysis, we will adjust for 
any imbalanced confounding variables using analogous methods. 
 
Treatment effect heterogeneity (treatment effect modification). In exploratory 
analyses we will assess whether the treatment effect on the primary outcomes of 
intubation success on the first attempt varies across levels of pre-specified baseline 
variables by assessing the treatment-by-covariate interaction in the relevant model.   
Factors of interest include experience level (experience versus not experienced), patient’s 
sex, patient’s body mass index (BMI), emergency vs. elective surgeries, full neck range-
of motion, limited neck extension, limited neck flexion, short neck, history of previous 
difficult intubation, short thyromental distance, non-compliant submandibular space, 
beard presents, anterior larynx, a priori expected difficulties during airway management, 
large epiglottis, large tongue, poor jaw range of motion, poor neck range of motion, 
recessed chin, and stylette required. 
 
An important potential effect modifier will be the learning curve of anesthesiologist on their 
skill with GlideScope videolaryngoscopy. We expect about a 3-month learning curve for 
the average provider. We will therefore assess the interaction between the treatment 
effect and time since start of the trial, dichotomized as early (first 3 months) versus late 
(after initial 3 months) on the primary outcome of number of intubation attempts.  This 
sensitivity analysis will also include graphical moving average displays of the proportion 

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over time with the outcome in each treatment group, and well as displays of the treatment 
effect over time (independent of the 3-month grouping). 
  
Interim Analyses. We will conduct interim analyses for efficacy and futility at each 25% 
of the planned enrollment using a group sequential design with a gamma spending 
function, with gamma parameter of -4 for efficacy and -1 for futility. Assuming the 
alternative hypothesis is as specified below in Sample Size Considerations, there will be 
a cumulative 9.4% probability of crossing a stopping boundary at the first look, 40% 
through the 2nd look, 78 % through the 3rd look and 100% by the last. Stopping boundaries 
will not be binding – the decision to stop or continue the trial will be made by the DSMB 
which will consider all available information in their decision.  
 
Sample size considerations. Sample size is based on the primary outcome, the number 
of intubation attempts (with either device).  About 5,000 operations per year will be 
performed during the anticipated 3-year enrollment period.   Based on a previous study, 
we expect that about 10% of patients may require more than 1 intubation attempt in the 
direct laryngoscopy group versus about 4% in the videolaryngoscopy group.31 (Direct 
laryngoscopy 1 attempt: 90%, 2 attempts: 4%; Videolaryngoscopy 1 attempt: 96%, 2 
attempts: 4%).  However, we plan the study to detect a slightly smaller effect, which also 
would be clinically relevant. 
 
We assume for sample size calculation that the proportion having 1, 2, 3 or more than 3 
attempts will be 0.90, 0.04, 0.03, 0.03 in the direct laryngoscopy group and 0.92, 0.04, 
0.02, 0.02 with videolaryngoscopy.  To detect this difference or a larger one with 90% 
power at the 0.05 significance level with a Mann-Whitney test we would need a total of 
8,800 patients, before accounting for interim analyses or within-cluster correlations. 
Accounting for a small within-cluster correlation of 0.01 and even smaller within-cluster 

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between-period correlation of 0.009, the required total sample size 32  is 13,112. Further 
adjustment for interim analyses requires a maximum total of 14,943 patients.    
 
Internal Pilot Study to Assess Sample Size Assumptions.  At the first interim analysis 
we will re-assess the distribution of the primary outcome in the direct laryngoscopy group 
only (since the prevalence can be considered a nuisance parameter analogous to 
standard deviation for a continuous outcome) as well as the assumed within-cluster and 
within-cluster between-period correlation.  We will resize the study if the required N based 
on the revised parameter estimates is noticeably higher than originally planned for the 
same planned treatment effect.  
 
Executive summary: Securing the airway is fundamental in surgical patients; a key 
component is endotracheal intubation, which is usually easy but sometime extraordinarily 
difficult. Direct laryngoscopy is generally used as the first-line airway device. 
Videolaryngoscopy improves airway visualization, but it remains unclear whether 
videolaryngoscopy reduces the number of intubation attempts. We therefore propose a 
large, robust trial powered to determine whether videolaryngoscopy reduces the need for 
multiple intubation attempts.  
 
Significance: Most surgical patients require endotracheal intubation. Although relatively 
rare, difficulties during endotracheal intubation can cause substantial patient morbidity 
including respiratory and hemodynamic instability, hypoxemia, cardiac arrest, 
regurgitation, aspiration, and airway trauma. The proposed study will extend available 
information and will determine whether videolaryngoscopy is superior to direct 
laryngoscopy, and whether videolaryngoscopy should be used initially in routine practice. 
 
Funding: This project is supported by an investigator-initiated grant by Verathon, 
Bothwell, WA. 
 
 
 
 
 

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Arnup SJ, McKenzie JE, Hemming K, Pilcher D, Forbes AB. Understanding the cluster 
randomised crossover design: a graphical illustraton of the components of variation and a 
sample size tutorial. Trials. 2017;18(1):381-381. 
 
 
 

17 
 
Chronological List of changes: 
Version 7 (march 27, 2022) 
• A sensitivity analysis has been added to the statistical methods. 
 
Version 6 (May 19, 2021) 
• The ClinicalTrials.gov identifier has been added. 
• The paragraph regarding video recording was updated. 
• The definition of intubation attempts have been updated and specified to reflect 
current routine practice. 
 
Version 5 (October 6, 2021) 
• Several Co-investigators have been added. 
• Video recording for teaching purposes has been added. 
• The ClinicalTrials.gov identifier has been added. 
• The definition of intubation attempts have been updated and specified to reflect 
current routine practice. 
 
Version 4 (November 3, 2020) 
• Title: ”quality improvement project” was replaced by “research project”  
• Several Co-investigators have been added. 
• Design: we changed the isolated set of operating rooms to the J operating suites, 
consisting of 22 operating suites (2 are currently not in use) and used for cardiac, 
thoracic and vascular procedures. 
• We further clarify, that we will divide the J OR’s in 2 separate clusters.  
• Inclusion criteria, we now enroll adults having cardiac, thoracic, or vascular 
surgery. 
• Exclusion, we now specify, that patient requiring a double lumen tube are 
excluded. 

18 
 
• Methods: etomidate was added as an alternate induction medication 
• Direct laryngoscopy. Using a Miller blade is now added as an alternative to the 
Macintosh blade. 
• Sample size considerations: number of surgeries are adapted to about 5.000 per 
year and the duration of this project for up to 3 years.  
• The sections on statistical analysis and Treatment effect heterogeneity have been 
updated. 
 
Version 3 (May 20th, 2020) 
• McGrath videolaryngoscope was replaced by GlideScope videolaryngoscope. 
• We added clarification, that this project will be performed in the G operating suite 
area. 
 
Version 2 (October 16 2019) 
• Exploratory hypothesis 1 and exploratory outcome 1 was added 
• The following paragraph was added “We will also capture the level of training of 
the person making the first intubation attempt and the final intubation attempts (if 
a switch of anesthesia providers occurred).” 
 
 

19 
 
Trial timeline: 
 
08/20/2019  
study protocol version 1 finalized 
09/11/2019  
initial submission of study protocol version1 submitted to IRB 
12/24/2020  
IRB approval granted (study protocol version 4) 
01/08/2021  
trial registration on www.clinicaltrials.gov 
03/15/2021  
Start of clinical training  
03/29/2021  
First patient enrolled 
06/11/2021 
AE reported to IRB 
02/26/2022 
enrollment paused due to transfer of documentation from 
ARKS to EPIC 
03/14/2022  
enrollment restarted