Accuracy of Pulse Oximeters With Profound Hypoxia
Condition: Oximetry
MeSH terms: Hypoxia
Study type: Observational

Summary: 
      To test the accuracy of a non-invasive blood oxygen saturation monitor which is placed on a
      subject with profound hypoxia.
    

Detailed description: 
      A radial arterial cannula was placed in either the left or right wrist of each subject for
      arterial blood sampling and blood pressure monitoring. Blood gas analysis to determine
      oxyhemoglobin saturation (SaO2)was performed using an ABL-90 multi-wavelength oximeter
      (Hemoximeter, Radiometer, Copenhagen, serial 1393-090R0359N0002). This instrument contains
      factory certified calibration standards and quality control algorithms.

      Each subject had two control blood samples taken at the beginning of each experiment, while
      breathing room air. Hypoxia was then induced to different and stable levels of oxyhemoglobin
      saturation (between 70-100%) by having subjects breathe mixtures of nitrogen, room air, and
      carbon dioxide. Each plateau level of oxyhemoglobin saturation was maintained for at least 30
      seconds or until reference pulse oximeters readings were stable. Two arterial blood samples
      were then obtained, approximately 30 seconds apart. Each stable plateau therefore was
      maintained for at least 60 seconds with SpO2 fluctuating by less than 2-3%. The plateaus were
      nominally at 100%, room air saturation, 93%, 90%, 87%, 85%, 82%, 80%, 77%, 75% and 70%. A
      total of 270 samples were obtained at the saturation plateaus across this span. Data were
      provided for analysis. At least 200 data points were collected for each type of oximeter and
      probe combination studied.

      Pulse oximeter data is taken as 5 second averages corresponding to the point of arterial
      blood analysis. Individual data points may be missed or excluded for dropped signals or
      failure of the oximeter signal to achieve an appropriate plateau. Data is plotted as
      Hemoximeter data (SaO2) vs. pulse oximeter bias (SpO2 - SaO2). A different marker is used for
      each study subject. Linear regression is shown for all subjects combined, and the equation
      with R2 is shown on the plot. Mean bias is displayed as a solid horizontal line, and the
      upper and lower limits of agreement (mean bias ± 1.96•SD*) are shown by dashed horizontal
      lines. For the "pooled" plots, different markers are used for each pulse oximeter. Tables of
      mean, standard deviation, standard error, minimum, maximum, 95% confidence interval, count
      and root mean square are provided for each oximeter's bias, and all oximeters combined in the
      following ranges of SaO2 (Hemoximeter): 60 - 80%, 80 - 100%, 60 - 100%, 70 - 100%, 50 - 60%,
      60 - 70%, 70 - 80%, 80 -90%, and 90 - 100%.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        All of the subjects enrolled in the study had normal hemoglobin levels (Hemoglobin ≤
        10gm•dl-1) and all were healthy non-smoking individuals of age 21-49.
      
Biospecimen description: 
      Whole blood.