Defense Date


Document Type


Degree Name

Master of Science


Health Related Sciences

First Advisor

William Hartland


This study utilized a quasi-experimental pretest-posttest design that compared the effect of body position changes on arterial oxygen saturation in obesity as measured noninvasively by pulse oximetry. The null hypothesis, that there would be no difference between oxygen saturation values measured by pulse oximetry with position change from sitting to supine in obese subjects as compared to nonobese subjects, was tested. Fourteen obese, American Society of Anesthesiologist (ASA) physical class status II subjects and 14 nonobese ASA physical class status I subjects were included in the sample population. Thirteen of the obese subjects were further classified as morbidly obese. After agreeing to participate, a pulse oximeter monitoring probe was placed on the subject's index finger. Under spontaneous room air ventilation, a pretest sitting arterial oxygensaturation was measured by a Nelcor® N-100 pulse oximeter (SpO2). Subjects were then placed supine on a stretcher for 10 minutes. Pulse oximetry values were recorded immediately following position change and then serially for 10 minutes. Macro analysis of the means across all measurements between both groups failed to reject the hypothesis. Repeated measures analysis of covariance (ANCOVA) revealed that the means across both groups for each Spoznwasurement approached significance (p = .089). Further micro analysis of the magnitude of change from the sitting to supine position between groups rejected the hypothesis. The ANCOVA established statistical significance between the mean supine SpO2 values (adjusted for baseline) across both groups between the immediate supine measurements and the 1 minute supine value (p = .001). Continued significance was displayed when analyzing the difference of the SpO2 values between the mean 1 minute supine and 2nd minute supine measurement (p = .041). The paired t-test determined which group had the significant change between measurements. It was demonstrated that the obese group had a statistical significant change in SpO2 values between the sitting and immediate supine (p = .007), immediate supine and 1 minute (p = .034), and 1 minute supine and 2nd minute supine (p = .013) measurements. The nonobese group had a statistical significant change in SpO2 value only from the sitting to the immediate supine measurement (p = .005).


Scanned, with permission from the author, from the original print version, which resides in University Archives.


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