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The Optimum Time for Preoxygenation Based on Body Mass Index

This study has been completed.
Information provided by (Responsible Party):
Roya Yumul, M.D.,PhD., Cedars-Sinai Medical Center Identifier:
First received: April 23, 2010
Last updated: February 14, 2012
Last verified: February 2012
The purpose of this study is to evaluate the relationship between the time needed to raise the oxygen concentration in patient's blood to 90% and his/or her body mass index. The prevalence of obesity in our society continues to rise. No studies have shown the time required for preoxygenation (oxygen given) in relation to body mass index (body weight in kg/height in meter2).

Body Weight

Study Type: Observational
Study Design: Time Perspective: Prospective
Official Title: The Optimum Time for Preoxygenation Based on Body Mass Index

Further study details as provided by Cedars-Sinai Medical Center:

Primary Outcome Measures:
  • Time to reach 90% end tidal oxygen saturation using monitor and stop watch [ Time Frame: 1 to 10 minutes ]
    Using monitors on the anesthesia machine, we recorded the end tidal oxygen saturation value and also recorded the time at which the end tidal oxygen was recorded. From the information collected the relationship between BMI and gender with the time to 90% end tidal oxygen saturation will be evaluated.

Enrollment: 75
Study Start Date: July 2007
Study Completion Date: October 2009
Primary Completion Date: October 2009 (Final data collection date for primary outcome measure)
Patients with BMI values between 18.5-24.9
Patients with BMI values between 25-29.9
Patients with BMI values between 30-49.9

Detailed Description:

100% oxygen given to patient before induction of anesthesia (asleep) is the standard clinical care. However, studies using various methods have shown differences in terms of the optimal time, technique and number of breaths needed for efficient oxygenation. The only difference to the standard pre-anesthesia care is that we will record the time to raise patient oxygen to 90%. Age is recorded to ensure that the subjects fall within our inclusion criteria. The weight (W) in kilograms and height (H) in meters will be used to calculate the body mass index (BMI): BMI = W/H2. Alveolar oxygen uptake is dependent on respiratory rate, heart rate, blood pressure, temperature and hemoglobin level. These parameters are measured in order to identify factors that may affect the accuracy of the study. We will record the pulse oximetry value to note the initial oxygen saturation on room air and after the oxygenation.

Facial hair and mask fit are recorded to assess possible failure of an optimal facemask seal. End-tidal carbon dioxide (FE'CO2) is also measured to ensure an adequate facemask seal. Anxiety can increase the respiratory rate, heart rate and affect patient compliance with a fitted facemask. All of the aforementioned values are recorded to assess reasons for possible failure of the preoxygenation technique and inaccurate results.


Ages Eligible for Study:   18 Years to 50 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Sampling Method:   Non-Probability Sample
Study Population
The study population will consist of 100 subjects between the ages of 18-50 classified as ASA 1 or 2 with no limitations as to gender or race that are scheduled for elective surgery at Cedars-Sinai Medical Center. There are changes to lung functioning as functional residual capacity (FRC), closing capacity, and lung volume after age 50; therefore, the age limitation is set to age 50. Changes in lung and chest wall compliance necessitate the exclusion of anyone over the age of 50. Minors are also excluded as there is difficulty fitting the face mask due to a smaller physiology.

Inclusion Criteria:

  • Participants between the ages of 18-50 years with no limitations as to gender or race
  • Participants classified as ASA 1 or 2
  • Participants capable of understanding and signing an informed consent

Exclusion Criteria:

  • Conditions which would affect their oxygenation such as heart disease, lung disease, anemia (Hemoglobin less than 12 g/dL)
  • History of smoking (smoking can affect pulmonary function and oxygen carrying capacity)
  • Acute substance abuse (substance abuse can affect respiratory function).
  • Maxillofacial abnormalities which would interfere with proper face mask seal.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01114932

United States, California
Cedars Sinai Medical Center
Los Angeles, California, United States, 90048
Sponsors and Collaborators
Cedars-Sinai Medical Center
Principal Investigator: Roya Yumul, MD, PhD Cedars-Sinai Medical Center
  More Information

Responsible Party: Roya Yumul, M.D.,PhD., Residency program director, Department of anesthesiology, Cedars-Sinai Medical Center Identifier: NCT01114932     History of Changes
Other Study ID Numbers: Pro00011544
Study First Received: April 23, 2010
Last Updated: February 14, 2012

Keywords provided by Cedars-Sinai Medical Center:
body mass index
end-tidal O2
anesthesia induction

Additional relevant MeSH terms:
Body Weight
Signs and Symptoms processed this record on April 27, 2017