Location
Utah State University
Start Date
5-10-2010 1:45 PM
Description
Background: We evaluated the functionality, feasibility of use at the bedside and repeatability of subsequent Functional Residual Capacity (FRC) measurements in mechanically ventilated ICU patients using a new system. The newly developed system had previously been assessed for accuracy in spontaneously breathing human volunteers.
Materials and Methods: We measured the FRC of the lungs of 20 mechanically ventilated ICU patients using the nitrogen washout/wash-in technique. Duplicate measures in each of the patients were analyzed for repeatability.
Results: The squared correlation coefficient for the linear regression between repeated measurements was r2=0.92 (n=39); y=0.99x +0.03. the bias +/- Standard Deviation was -0.009 +/- 0.212 L (-0.4 +/- 8.9%). The Limits of agreement (mean +/- 2*SD) were between -0.42 and 0.41 L (-17.9 to 17.1%).
Conclusion: These results indicate FRC measurement is repeatable within a clinically acceptable range. This method compares favorably with other methods recently reported in the literature. This system could possibly be used in space to monitor lung volume, especially as it relates to pulmonary disease in weightlessness.
Measurement of Functional Residual Capacity of the Lung by Nitrogen Washout/Wash-in in Mechanically Ventilated ICU Patients
Utah State University
Background: We evaluated the functionality, feasibility of use at the bedside and repeatability of subsequent Functional Residual Capacity (FRC) measurements in mechanically ventilated ICU patients using a new system. The newly developed system had previously been assessed for accuracy in spontaneously breathing human volunteers.
Materials and Methods: We measured the FRC of the lungs of 20 mechanically ventilated ICU patients using the nitrogen washout/wash-in technique. Duplicate measures in each of the patients were analyzed for repeatability.
Results: The squared correlation coefficient for the linear regression between repeated measurements was r2=0.92 (n=39); y=0.99x +0.03. the bias +/- Standard Deviation was -0.009 +/- 0.212 L (-0.4 +/- 8.9%). The Limits of agreement (mean +/- 2*SD) were between -0.42 and 0.41 L (-17.9 to 17.1%).
Conclusion: These results indicate FRC measurement is repeatable within a clinically acceptable range. This method compares favorably with other methods recently reported in the literature. This system could possibly be used in space to monitor lung volume, especially as it relates to pulmonary disease in weightlessness.