A Prospective, Randomized, Non-Blinded, Crossover Controlled Clinical Trial Evaluating the Efficacy of Face Mask Ventilation With 45 Degree Head Rotation in Anesthetized Obese (BMI ≥ 35) Adults
Phase: NA
Conditions: Noninvasive Ventilation
Sponsor: University of Missouri-Columbia

BIOMEDICAL RESEARCH PROTOCOL  
UNIVERSITY OF MISSOURI 
 
Project Title: A Prospective, Randomized, Non-Blinded, Crossover Controlled 
                     Clinical Trial Evaluating the Efficacy of Face Mask Ventilation with 45 
                     Degree Head Rotation in Anesthetized Obese (BMI ≥ 35) Adults 
IRB Number: 2012364 
Version Number: 1 
Version Date: 08/24/2018 
Principal Investigator: Boris Mraovic, MD 
Funding Source: Departmental  
Clinicaltrials.gov Number: NCT03876873 
 
 
 
PI: Boris Mraovic, MD1, 2 
 
Associate Professor 
 
Co-I: Michael S. Lasky, BS2 
Medical Student 
 
Co-I: Noah Timko, BS, BHS1, 2  
Research Specialist 
 
1Department of Anesthesiology and Perioperative Medicine 
2School of Medicine 
University of Missouri 
Columbia, Missouri 65212 
 
 
 
Primary Contact: Boris Mraovic, MD 
Department of Anesthesiology and Perioperative Medicine 
University of Missouri–Columbia 
One Hospital Drive, C2053; DC005.00 
Columbia, MO 65212 
Telephone: (573) 882-2568 
Fax: (573) 882-2226 
Email: mraovicb@health.missouri.edu 

2 
 
2.1 Objectives: 
This prospective, randomized, non-blinded, crossover controlled clinical trial will enroll 
subjects with a BMI ≥ 35 who are undergoing elective surgical procedures. Subjects will 
be randomized to receive mask ventilation after general induction of anesthesia in either 
a neutral head position (practice standard position) or a head rotation position (45 
degree angle) to determine: 
 
Primary Endpoint: 
1. Maximal and average expiratory tidal volume during mask ventilation 
 
Secondary Endpoints: 
1. Maximal and average inspiratory tidal volume during mask ventilation 
2. Maximal and average end-tidal CO2 (ETCO2) during mask ventilation 
3. Maximal and average airway flow L/min during mask ventilation 
4. Lowest and delta O2 saturation drop on SpO2 during mask ventilation 
5. Lowest and delta O2 saturation drop on SpO2 during intubation 
 
2.2 Clinical Hypotheses: 
Primary Hypothesis: 
We hypothesize that a 45 degree head rotation during mask ventilation will: 
1. Increase the efficacy of mask ventilation measured by tidal volumes 
 
Exploratory Hypotheses: 
We hypothesize that a 45 degree head rotation during mask ventilation will: 
1. Decrease upper airway obstruction measured by airway flow 
2. Improve oxygenation measured by SpO2 during mask ventilation 
3. Improve oxygenation measured by SpO2 during intubation 
 
 

3 
 
3.1 Background & Rationale: 
Mask ventilation is a foundation of airway management after the initial induction of 
anesthesia.  It allows for adequate oxygenation of the patient to buy enough time for 
intubation, during which the patient is not ventilated.  However, in some patients mask 
ventilation may be difficult – older than 55 years, heavier (BMI > 26 kg/m2), with no 
teeth, having a beard or sleep apnea.1,2,3  Inadequate ventilation, if not corrected, can 
result in decreasing oxygen saturation to dangerous levels – which could lead to 
devastating complications.  As a result, the efficacy of mask ventilation is of critical 
importance to patient safety after the induction of anesthesia.  
 
A recent study proposed that mask ventilation could be improved simply by turning a 
patient’s head.  The study showed that rotating a patient’s head to a 45 degree angle 
significantly improved mask ventilation when compared with the head placed in a neutral 
position.4   However, this study was done in patients with a BMI less than 35.  As such, 
the effects of head rotation on the efficacy of mask ventilation has not been studied in 
patients with a BMI of 35 and greater. 
 
Obesity (BMI ≥ 30 kg/m2) affects almost 40% of US adults and is one of the most 
prevalent health concerns in our society.5  It is a predictor of difficult mask ventilation 
because it is associated with increased upper airway obstruction, decreased airway 
patency, and decreased lung volumes such as functional residual capacity (FRC).1  If 
previous findings in regard to the effect of 45 degree head rotation on the efficacy of 
ventilation hold true in the obese patient, then this study will show that head rotation 
could be used as a simple way to improve the efficacy of mask ventilation for patients 
with a BMI of 35 and above.4 
 
4.1 Study Design: 
This will be a prospective, randomized, crossover, non-blinded, controlled clinical trial 
performed at a single academic hospital. 

4 
 
4.2 Study Design: 
 
 
 
 
 
 
 
 
 
4.3 Study Procedures: 
I. Subject Population: this study will enroll 38 adults undergoing elective surgery 
requiring general anesthesia with intubation of the trachea.   
 
II. Inclusion Criteria: 
a. Age ≥ 18 years 
b. ASA I-III 
c. BMI ≥ 35 kg/m2 
 
III. Exclusion Criteria: 
a. Inability to obtain written informed consent 
b. Pregnant or breastfeeding 
c. Limited head rotation or neck extension 
d. Subjects with expected or history difficult intubation 
e. Large beard 
f. OG/NG tube  
g. GERD 
Sample (38) 
Group A (19) 
Step 1: Neutral Position (1min) 
Step 2: Head Rotation (1min) 
Step 3: Neutral Position (1min) 
Randomization 
Group B (19) 
Step 1: Head Rotation (1min) 
Step 2: Neutral Position (1min) 
Step 3: Head Rotation (1min) 

5 
 
IV. Randomization: On the day of surgery, before the induction of anesthesia subjects 
will be randomized into either Group A or Group B.  Randomization will be 
accomplished by the method of randomized permuted block. The two groups will 
be stratified so that obese subjects with a BMI ≥ 35 and ≤ 44 and those with a 
BMI ≥ 45 are equally distributed between both groups. Groups will be additionally 
stratified by the presence or lack of obstructive sleep apnea (OSA). 
 
V. Blinding: Group assignment will not be known by research staff at the time of subject 
recruitment. No blinding will occur during the clinical portion of the study or during 
data analysis. 
 
VI. Preoperative Data Collection and Measurements: Before the subject is taken into the 
operating room, we will record and measure age, BMI, sex, ASA status, preop 
diagnoses, OSA, procedure being done, Mallampati score, mouth opening, thyro-
mental distance, neck circumference, neck range of motion, lack of teeth, 
presence of beard, and history of snoring.  
 
VII. Anesthetic Management 
a. Monitoring 
1. All subjects will be monitored with standard perioperative monitors: ECG, 
non-invasive blood pressure, pulse oximetry, esophageal temperature, 
and capnography. 
 
b. Anesthetic Technique  
1. All subjects will receive a standardized general anesthetic technique and 
all anesthetic medications will be dosed on the ideal body weight rather 
than actual body weight.  
2. Preoxygenation – 100% oxygen delivered via face mask for a minimum of 
3 minutes 

6 
 
3. Induction – intravenous delivery of propofol, 1.5-2.0 mg/kg, fentanyl, 1 
µg/kg, and rocuronium, 0.6 mg/kg. Additional propofol or fentanyl may be 
administered at the discretion of the anesthesia provider. 
4. Mask Ventilation – start when subject loses consciousness. Ventilation 
settings will be pressure controlled ventilation 20 cmH2O. Respiratory 
Rate will be 16. Group A will receive 1 minute of neutral head position 
followed by 1 minute of 45 degree head rotation to the right and then 1 
minute of neutral head position.  Group B will be the opposite.  If mask 
ventilation is difficult or SpO2 saturation drops below 90% the subject will 
be excluded from the study. Immediately after exclusion the standard of 
care ventilation will be resumed.  
5. Intubation – will be in the standard of care fashion after the 3 sets of head 
positions are completed. Usually the endotracheal intubation is after 2-3 
minutes after induction. Our study may increase that time by 1 or 2 
minutes. 
6. The study will conclude with intubation of the trachea. The rest of the 
subject management will be per anesthesia clinical team standard of 
care. 
 
c. Extubation  
1. Standard of care.   
 
VIII. Postoperative Pain Management 
a. Standard of care. 
 
4.4 Costs: 
The cost of the Medline Top Valve Anesthesia Mask used in this study will be billed to 
subjects’ insurance as normal standard of care at University Hospital. Face masks are 
used on surgical patients as standard of care following University Hospital Department 
of Anesthesiology and Perioperative Medicine protocol. They are necessary for 

7 
 
preoxygenation of patients before surgical procedures. Taking part in this study will 
bring no additional cost to subjects.  
 
4.5 Study Duration: 
Study will start in September 2018 and last one year. 
 
5.1 Statistical Analysis and Sample Size Justification: 
A power analysis using a predicted tidal volume of 450 ml for group A and 520 ml for 
group B, with a standard deviation of 75 ml, determined that 19 subjects per group 
would be needed to achieve a power of 80% with an alpha error of 5%. 
 
6.1 Publication Plan 
We plan to present this data at anesthesiology meetings.  We will target the American 
Society of Anesthesiologists Annual meetings for abstract presentations and the journal 
Anesthesiology for publication of the final data.   
 
 
 
 
 
 
 
 
 
 
 
 

8 
 
7.1 References: 
1. Langeron O, Birenbaum A, Le Sache F, & Raux M. Airway management in obese 
patient. Minerva Anestesiol. 2014; 80:382-392. 
 
2. Kheterpal S, Han R, Tremper KK, Shanks A, Tait AR, O’Reilly M, & Ludwig TA. 
Incidence and predictors of difficult and impossible mask ventilation. 
Anesthesiology 2006; 105:885–891. 
 
3. Kheterpal S, Martin L, Shanks AM, & Tremper KK. Prediction and outcomes of 
impossible mask ventilation: A review of 50,000 anesthetics. Anesthesiology 
2009; 110:891–897. 
 
4. Itagaki T, Oto J, Burns SM, Jiang YJ, Kacmarek RM, & Mountjoy JR. The effect 
of head rotation on efficiency of face mask ventilation in anaesthetised apnoeic 
adults. European Journal of Anesthesiology. 2017; 34:432-440. 
 
5. Hales CM, Carroll MD, Fryar CD, & Ogden CL. Prevalence of obesity among 
adults and youth: United States, 2015-2016. National Center for Health Statistics 
288th ed. CDC; 2017:1-8. 
 
6. Chapter 19. Airway Management. In: Butterworth JF, IV, Mackey DC, Wasnick 
JD. eds. Morgan & Mikhail's Clinical Anesthesiology, 5e New York, NY: McGraw-
Hill; 2013.