Comparing Time to Readiness for Discharge After Colonoscopy: Propofol and Dexmedetomidine vs Propofol Only Sedation
Phase: PHASE4
Conditions: Colonoscopy
Sponsor: State University of New York - Downstate Medical Center

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NCT03139279 
 
Comparing Time to Readiness for Discharge After Colonoscopy: Propofol and 
Dexmedetomidine vs Propofol Only Sedation 
 
PROTOCOL Version 2/21/2018 
 
Principal investigators: Dennis Dimaculangan MD 
 
Other investigators: 
Leonard Edokpolo MD 
Jeremy C. Weedon PhD 
Joanna Serafin, PhD 
James Kim, M.Eng. 
Isabelle Kao, B.A. 
Alexander Lo, B.S.  
Maryam Siddiqui, B.S. 
Frederick Jacques, B.S. 
 

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1.  INTRODUCTION: 
Colonoscopy is an important diagnostic screening procedure for colon cancer that is 
often associated with discomfort therefore requiring moderate to deep sedation of 
patients. Monitored Anesthesia Care (MAC) sedation is the technique that is widely 
provided and is considered the standard of practice in the United States for patients 
undergoing colonoscopy [1]. An ideal sedative agent for ambulatory colonoscopy should 
have certain properties that include: a rapid onset and offset of action, provide 
cardiopulmonary stability, have minimal adverse effects, and allow for smooth recovery, 
and early discharge [4, 5]. 
  
Titrated bolus dosing or continuous infusion, of propofol alone, is the commonly 
used technique for Monitored Anesthesia Care (MAC) in ambulatory colonoscopy. Propofol 
is chosen because of its rapid onset and short duration of action, a property which is ideal 
for fast recovery and early discharge in the ambulatory setting. Depending on a patient’s 
comorbidities, age and functional status, there is a wide range of variability in the 
hemodynamic and respiratory responses with sedative doses of propofol. Careful propofol 
titration is therefore required to avoid hypotension and hypoventilation. Hypotension and 
apnea can occur if large doses of propofol are required to complete the procedure [1, 6, 7]. 
 Balanced anesthesia, using a combination of medications with different 
mechanisms of action can be used as a technique to minimize the total amount of each 
agent given and their side effects while achieving the desired level of sedation. 
Dexmedetomidine is one agent that has been used alone or in combination with propofol 
for sedation during colonoscopy. 
 Dexmedetomidine is an alpha-2 adrenergic receptor agonist with analgesic and 
sedative effects [8]. Other desirable effects for this agent include: decrease requirements 
for other anesthetics and analgesics, minimal respiratory depression, neuroprotection, and 
decrease in emergence agitation [9-11]. On the other hand, dexmedetomidine has been 
reported to be associated with prolonged post-operative recovery time due to bradycardia, 
low mean arterial pressure, and cardiovascular depression [12-14]. 
 While several studies have examined the use of dexmedetomidine in colonoscopy, 
there is limited evidence on its efficacy when combined with propofol for use in 
ambulatory colonoscopy. One study that demonstrated the safe use of dexmedetomidine 
alone for colonoscopy also concluded that its sole use in this setting is limited by its side 
effects such as, hemodynamic instability, prolonged recovery, and a “complicated 
administration” [15]. In another study, dexmedetomidine was shown to provide better 
hemodynamic stability, higher Ramsay sedation scale score, and higher satisfaction scores 
in comparison to midazolam [16]. A randomized study that compared four different drugs: 
dexmedetomidine, sufentanil, meperidine and midazolam used in combination with 
propofol for sedation in colonoscopy showed that patients who received dexmedetomidine 
and propofol had a higher degree of sedation and shorter time to recover protective 
reflexes and motor function [4]. 

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 Only one study in the literature has directly compared a dexmedetomidine-propofol 
regimen with propofol alone for sedation during colonoscopy. In this Chinese study, 
investigators found that oxygen saturation level, and the amount of propofol consumed in 
patients who received dexmedetomidine-propofol are decreased in comparison with those 
who received propofol only [17]. The study investigators determined that there was no 
difference in recovery time between a combination of dexmedetomidine-propofol 
compared to propofol-only. However, recovery time in the study was defined as time from 
the last dose of medication to the time when the patient became alert and oriented to their 
name, age and to time. This definition of recovery does not necessarily mean that the 
patient is ready for discharge to home, which will be more relevant to the clinical 
implications of the findings in the ambulatory surgical setting. In the United States, phase 2 
recovery from anesthesia and readiness for discharge to home is based on a specific 
criteria that is defined by the Modified Post Anesthesia Discharge Scoring System 
(MPADSS), shown in Table 1 (18, 19). Compared to the Aldrete score (Table 2), the 
MPADSS system does not only provide criteria for discharge from the post anesthetic care 
unit (PACU), but also provides criteria for “street fitness,” such as severity of pain, ability to 
stand and ambulate, and tolerance of oral fluids so that patients can be discharged to home 
(20,21).  
 We did not find any study in the literature that has definitively assessed whether 
dexmedetomidine-propofol prolongs readiness for discharge in the ambulatory setting 
when compared to a propofol-only regimen for sedation. 
 Some practitioners at the SUNY Downstate Medical Center have started combining 
dexmedetomidine with propofol for sedation of patients undergoing colonoscopies. Due to 
the importance of rapid recovery and patient turnover in an ambulatory surgery setting, 
we plan to conduct a prospective randomized double-blind study on patients scheduled to 
undergo colonoscopy to compare the combination regimen of dexmedetomidine-propofol 
to a propofol-only regimen and determine whether there are any differences in recovery 
time and readiness for discharge as defined by the Modified Post Anesthesia Discharge 
Scoring System (MPADSS) scale. 
  
2. OBJECTIVES 
 
We will prospectively compare a group of patients randomized to receive propofol 
and dexmedetomidine to another group of patients randomized to receive propofol alone. 
We hypothesize that there will be no significant difference in the time to readiness for 
discharge between the two groups using the MPADSS discharge scale.  
 
3. STUDY DESIGN AND METHODS 
This is a prospective study to compare in a randomized double blind trial the following 
outcome measures: 

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Primary outcome: 
1. Readiness for discharge time: 
From the time of last administration of sedative medication to the time for the 
patient to attain Modified Post Anesthesia Discharge Scoring System (MPADSS) 
score of 9-10. The evaluation of time to discharge will involve the assessment of 
patients every 10minutes. Since almost every patient is discharged within an hour, 
the measure is very granular; we propose therefore to dichotomize it as discharge 
within 30min, yes or no. 
 
Secondary outcomes: 
1. Total propofol consumption per group (mg/kg)/duration of procedure in minutes 
2. Side effects:  
a. lowest intraoperative % drop in MAP from baseline 
b. sustained bradycardic episode (HR<50 for at least 5 minutes) 
intraoperatively, to be reported as a yes/no event 
c. number of apneic episodes, intraoperatively, requiring positive pressure 
ventilation. To be reported per group 
 
A. Type of study 
This is a non-inferiority prospective randomized double blind study. 
 
B. Patient selection 
i. 
Requested Sample Size: Up to 150 people will be screened until the study 
achieves 100 cases (excluding screen failures and withdrawals) - 50 patients to 
receive intravenous Dexmedetomidine 0.3 ug/kg followed by propofol; 50 
patients to receive propofol-only plus placebo. 
ii. 
Inclusion and Exclusion Criteria:  
Inclusion criteria: 
 All patients scheduled to undergo colonoscopy at SUNY Downstate 
Medical Center. 
Exclusion Criteria 
 < 18 years old 
 > 75 years old 
  Cognitively Impaired patients (Cognitively impaired patients are 
excluded from the study because our primary outcome involves a very 
strict discharge criteria that requires the patient to respond to and 
perform tasks on our pre-existing discharge scale checklist. These may be 
impossible to assess or will be difficult to standardize for patients whom 
are Cognitively Impaired.) 
 Pregnancy 
 Patients who use a wheelchair or ambulates with crutches (Patients using 
a wheelchair are excluded from the study because our primary outcome 
involves a very strict discharge criteria that requires the patient to 
respond to and perform tasks on our pre-existing discharge scale 

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checklist. These may be impossible to assess or will be difficult to 
standardize for patients whom who use a wheel-chair). 
 Limited exercise tolerance (as this could represent active coronary 
disease) 
 Total body weight greater than 150 kg (due to maximal dose of drug 
available in randomized syringes containing study drug) 
 Propofol, soy or glycerol allergy 
 Significant renal impairment 
 Significant hepatic impairment 
 Inability to read or write in English 
iii. 
Method for Screening For Eligibility: 
 Screening for Cognitively Impaired patients 
o pre-existing clinical diagnosis of cognitive impairment in medical 
history 
 Screening for pregnancy 
o Based on urine or serum HCG pregnancy test done as part of 
routine preoperative evaluation prior to administration of 
anesthesia. 
 Screening for renal impairment 
o Based on glomerular filtration rate <60 using routine preoperative 
basic metabolic panel. 
 Screening for other issues 
o As documented in health records or reported by the patient 
 
iv. 
Inclusion of Vulnerable Populations: Minors will not be included. Pregnant 
women will not be included. Cognitively Impaired individuals will not be 
included. To mitigate undue influence of patients recruited by their provider, a 
member of the research team who is not directly involved in the anesthetic 
management of the patient will be responsible for recruiting and consenting the 
patients for this research study. Minorities and women will be included, but are 
not specifically being targeted for inclusion.  Since a significant percentage of our 
patient population are minorities, it is important to include this group in our 
research study. Minorities will receive the same recruitment and randomization 
process as non-minorities. We will emphasize their right to withdraw from the 
study at any point and encourage them to ask questions about any issues of 
concern. 
v. 
Recruitment Procedures: Study staff will recruit participants through direct 
subject contact. This would occur after the patient has been evaluated and 
consented for anesthesia by a different anesthesia clinical team member that is 
not involved in the study. Recruitment will be done in the preoperative area 
separate by a study staff who is not directly involved in the clinical management 
of the patient.  
vi. 
Discontinuation of Study Subject/Withdrawal: The study may be discontinued at 
any time.  The participant can opt out at any time. The PI can withdraw the 
participant for reasons such as: participant meets one or more of the exclusion 

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criteria listed above or it is determined that participation in the study will be 
harmful to the participant. 
 
C. Procedures and Data collection 
Randomization procedure: 
Patients will be randomized, 50 patients in each group by using an electronically 
generated randomization table to determine the patient’s group assignment 
(random assignment similar to a flip of a coin). One group will receive intravenous 
Dexmedetomidine 0.3 ug/kg followed by propofol, and the other group will receive 
propofol-only plus placebo.  The level of sedation in each subject will be monitored 
by use of a Bispectral Index (BIS) monitor. The anesthesiologist will not be allowed 
to view the BIS monitor until after the first dose of propofol is administered. This is 
to ensure that the anesthesiologist is not provided with information that may allude 
to which arm the patient was randomized to. Additional doses of propofol will be 
given at the discretion of the anesthesiologist based on level of sedation to maintain 
a BIS level of approximately 60. 
The anesthesiologist will be blinded to the study group of each subject and will 
receive a premixed syringe containing either dexmedetomidine or placebo but 
labelled as dexmedotimidine 4 mcg/ml. Randomization will be performed by a 
research pharmacist who will determine the patient’s group assignment based on 
an electronically generated randomization table. This investigator will then give the 
respective pre-labeled syringe to the anesthesiologist and record the patient’s 
assignment in a password protected electronic data collection sheet. It will not be 
necessary to un-blind the care providers if an adverse event occurs because the 
management of likely adverse events are independent of the treatment arm and are 
based on clinical signs and findings in the evaluation of the patient. 
Data to be gathered from all participants will include: age, gender, body mass index 
(BMI); American Society of Anesthesiologists (ASA) classification; duration of 
procedure; procedure start and end times, time of the initial dose of sedatives given 
as well as the time of the last dose of medication administration. The total dose of 
propofol administered will also be recorded. 
Recovery will be assessed using the Modified Post Anesthesia Discharge Scoring 
System (MPADSS). This criteria is chosen because it has been proven as an efficient 
system that guarantees safe discharge. [18, 19]. This should be reliable and valid for 
use in this study because the purpose is to determine the point where patients have 
sufficiently recovered from sedation to be safely discharged from the ambulatory 
post anesthesia care unit. Data will be recorded immediately at the end of the 
procedure and every 10 minutes until the patient meets discharge criteria. 
Discharge criteria will be defined as a score of 9 or greater in the MPADSS scale. In 

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addition, we will also record the immediate postoperative Aldrete score (Table 2) in 
the operating room. The Aldrete score can be used to follow the awakening process 
of patients after an anesthetic experience as well as to determine eligibility for 
discharge from the PACU to the hospital ward. This method is accepted by the Joint 
Commission of Accreditation of Health Care Organizations in the United States and 
by similar regulatory agencies internationally [20]. We plan to report and compare 
the immediate post-operative Aldrete score as average score in each study group 
upon immediate assessment postoperatively. 
Vital signs will be recorded preoperatively, immediately at the end of the procedure 
and also at 10 minute intervals until the patient meets the discharge criteria as 
previously described. Postoperative requirement for medical interventions to 
correct vital signs, to treat pain or nausea will also be recorded. The individual 
recording the data will also be blinded to the group assignments to avoid bias. 
 
4. STUDY SITE: 
SUNY Downstate Medical Center, Brooklyn, NY 
 
5. STATISTICAL CONSIDERATIONS 
 
This study is characterized as a 2-arm, randomized non-inferiority trial. 
 
 
A. Principal outcome of interest: 
The evaluation of time to discharge will involve the assessment of patients every 
10minutes. Since almost every patient is discharged within an hour, the measure is 
very granular; we propose therefore to dichotomize it as discharge within 30min, 
yes or no. 
 
B. Sample size considerations: 
We project from past experience that in the single-drug arm, probability of patient 
discharge within 30min will be 0.90. We project that the same probability will apply 
to the two-drug arm; but we assert that if this number were as low as 0.70, the extra 
inconvenience to all concerned would be minimal; in other words, this differential 
represents a threshold of clinical significance, and we aim to demonstrate with 
reasonable certainty that the actual differential is smaller. Assuming equal numbers 
of subjects in each study arm, the power of the Pearson chi-square test to detect a 
differential as small as this is 90% for N=37 per arm, given a 2-tailed test and 
significance level of 0.05. However, that test is not always accurate for low 
prevalences, so we aim instead for N=50 per arm, which should yield an expected 
frequency of 5 or more in each cell of the 2x2 table that constitutes the principal 
analysis. Outcomes will be evaluated with the fisher’s exact test and the Mann-
Whitney U test for non-parametric variables as detailed below. 
 

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We project that we can consent about 4 patients per week into the study, which 
suggests that the enrollment window will be about 6 months. 
 
C. Data analysis plan: 
Subjects’ biometric, demographic and medical history characteristics as listed above 
will be recorded and summarized in a 2-way table, i.e., broken down by study arm 
membership, showing quartiles and min-max values for scored quantities, 
numerators and denominators with %s for classified quantities. 
 
There are 3 outcomes of interest:  
1. discharge within 30min; 
a. Specifically looking at whether there is a statistically significant 
difference in the number of patients discharged within 30 minutes in 
both treatment groups. 
2. mg propofol administered per kg bodyweight per minute of procedure; 
3. change in mean arterial pressure from pre-procedure baseline to lowest value 
observed during procedure. 
a. Difference in hemodynamic variables in blood pressure will serve as 
evidence of whether patients in the experimental group tolerated the 
study drug combination better than patients in the control group. 
 
Presentation of outcome summary data will be conducted as described above. 
Fisher’s exact test will be used to evaluate the first outcome; a supplementary 
Mann-Whitney test of between-arm difference in distribution of actual discharge 
times will be conducted. Mann-Whitney tests will be used for the other two 
outcomes. Given that this is a randomized study with decent sample sizes, we do not 
propose to construct regression models that attempt to control for differences 
between study arms. And given the nature of the intervention under evaluation, 
“intent to treat” considerations are essentially irrelevant. 
 
6. RISKS 
There is an occasional risk of a bradycardia following administration of dexmedetomidine. 
This is usually self-limited and resolves within a few hours particularly given the very small 
dose of dexmedetomidine needed for this study. If the heart rate is significantly slow, a 
small dose of glycopyrolate can be administered with expected immediate effect. Risk of 
glycopyrolate include tachycardia and dry mouth, however we do not expect these side 
effects because very small doses of glycopyrolate are required to correct the bradycardia.  
 
There is also an occasional risk of hypotension following administration of 
dexmedetomidine. If the blood pressure is significantly low, a small dose of ephedrine can 
be administered with expected immediate improvement in blood pressure.  Risks of 
ephedrine include tachycardia but this is usually self-limited and does not require 
treatment particularly given the small dose of ephedrine required to correct the 
hypotension from dexmedetomidine. 
 

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Furthermore, the bradycardia and hypotension are usually self-limited, easily treated and 
will be readily detected with the use of standard ASA monitors required for routine 
colonoscopy and while in the recovery room. 
 
There is also a potential for feelings of coercion or undue influence because of the 
recruitment of participants from the study team's own patient population. To mitigate this 
undue influence, recruitment and informed consent will be performed by a member of the 
research team that is not directly involved in the clinical care of the patient. 
 
In addition, there is the potential for a breach of confidentiality given the collection of 
protected health information in this study. The medical record number will be the only 
information on the data sheet linking the protected health information to the patient. 
Additionally, information will be stored in a password protected document. 
 
We do not expect any other additional risks to the subject beyond that which is expected 
for a routine outpatient colonoscopy procedure. The proposed study does not deviate from 
standard of care and patients in each study group will be receiving the same quality of 
anesthesia that they would otherwise receive whether or not they are enrolled in our 
study. Currently, anesthesiologists at SUNY Downstate Medical Center have the choice to 
use a combination of the drugs dexmedetomidine and propofol as a method of sedation or 
use the drug propofol alone.  This investigation simply allows us to collect and analyze data 
on the current practices to improve the standard of care.  
 
The investigators believe that the benefits of the knowledge gained from this study 
outweigh the risks of performing it. Results of this study could encourage more 
anesthesiologists to employ this technique of balanced anesthesia that minimizes the side-
effects of each drug administered with a predictable expectation of how patients will 
recover from the treatment. 
 
7. BENEFITS 
Although no direct benefits will apply to the subjects being studied, the results of this 
investigation could encourage more anesthesiologists to employ this technique of balanced 
anesthesia that minimizes the side-effects of each drug administered with a predictable 
expectation of how patients will recover from the treatment. 
 
8. INFORMED CONSENT 
Informed consent will be obtained from each subject by a member of the research team in 
the pre-operative area after the anesthesiology consent and evaluation has been completed 
by a separate clinical team member that is not involved in the study. Patient’s PHI will be 
protected in compliance with IRB and HIPA regulations. 
 
 
9. CONFIDENTIALITY 
Information about study subjects will be kept confidential and managed according to the 
requirements of the Health Insurance Portability and Accountability Act of 1996 (HIPAA). 
Patient data will be entered into a password protected electronic spreadsheet. Only the 

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investigators, who have been invited to participate in the study and who are registered 
with the IRB as well as have documented completion of all IRB, HIPAA, and CITI 
certifications will have access to the file and password. Electronic records will be stored for 
five years after study conclusion on the agreed upon investigator’s laptop computer, after 
which time they will be deleted. These records will be encrypted and password protected.  
 
 
10. ADVERSE EVENT REPORTING 
If there is a breach in confidentiality, adverse event, or violation of IRB or HIPAA 
regulations, the IRB will be notified in a timely manner as required by SUNY DMC policy 
and appropriate actions taken thereafter.  
 
11. FOLLOW-UP AND RECORD RETENTION 
Electronic records will be stored for five years after study conclusion on the agreed upon 
investigator’s laptop or desktop computer that is stored in the investigators office at the 
hospital. These records will be encrypted, password protected and available only to the 
investigators invited to participate in the study and who have fulfilled all requirements 
outlined by IRB and HIPAA policies. Five years after the study is closed with the IRB, all 
documents will be deleted. 
 
12. CONFLICTS OF INTEREST 
All investigators have no conflict of interests in regards to the proposed study. 

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Table 1 
Modified Postanesthestic Discharge Scoring System  
(Score ≥ 9 for discharge) 
VITAL SIGNS 
 
Within 20% of preop value 
2 
 
20 – 40% of preop value 
1 
 
40% of preop value 
0 
AMBULATION 
 
Steady gait/no dizziness 
2 
 
With assistance 
1 
 
None/dizziness 
0 
NAUSEA/VOMITING 
 
Minimal 
2 
 
Moderate 
1 
 
Severe 
0 
PAIN 
 
Minimal 
2 
 
Moderate 
1 
 
Severe 
0 
SURGICAL BLEEDING 
 
Minimal 
2 
 
Moderate 
1 
 
Severe 
0 
 
Table 2 
Modified Aldrete Score System 
Activity: Able to move (voluntarily or on command) 
 
Four extremities 
2 
 
Two extremities 
1 
 
No extremities 
0 
Respiration 
 
Able to breathe deeply or cough freely 
2 
 
Dyspnea, shallow, or limited breathing 
1 
 
Apnea 
0 
Circulation 
 
BP+/- 20 mm Hg of preop level 
2 
 
BP +/- 20 – 50 mm Hg of preop level 
1 
 
BP +/- 50 mm Hg of preop level 
0 
Consciousness 
 
Fully awake 
2 
 
Arousable  on calling 
1 
 
Unresponsive 
0 
Oxygen saturation 
 
SpO2 >92% 
2 
 
Needs supplement O2 to maintain SpO2>90% 
1 
 
SpO2 <90% with oxygen 
0 

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