The Optimum Time for Preoxygenation Based on Body Mass Index

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).

Study Overview

• Status: Completed
• Conditions: Obesity; Body Weight

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.

• Study Type: Observational
• Enrollment (Actual): 75

Contacts and Locations

Study Locations

• United States
  • California
    • Los Angeles, California, United States, 90048
      • Cedars Sinai Medical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

• 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.

Description

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.

Study Plan

How is the study designed?

Number of groups / cohorts

3

Cohorts and Interventions

Group / Cohort
BMI-I; Patients with BMI values between 18.5-24.9
BMI-II; Patients with BMI values between 25-29.9
BMI-III; Patients with BMI values between 30-49.9

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to reach 90% end tidal oxygen saturation using monitor and stop watch	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.	1 to 10 minutes

Collaborators and Investigators

• Sponsor: Cedars-Sinai Medical Center

Study record dates

Study Major Dates

• Study Start: July 1, 2007
• Primary Completion (Actual): October 1, 2009
• Study Completion (Actual): October 1, 2009

Study Registration Dates

• First Submitted: April 23, 2010
• First Submitted That Met QC Criteria: April 30, 2010
• First Posted (Estimate): May 3, 2010

Study Record Updates

• Last Update Posted (Estimate): February 15, 2012
• Last Update Submitted That Met QC Criteria: February 14, 2012
• Last Verified: February 1, 2012

More Information

Terms related to this study

• Keywords: body mass index; pre-oxygenation; anesthesia induction; end-tidal O2
• Additional Relevant MeSH Terms: Body Weight
• Other Study ID Numbers: Pro00011544