Correspondence  |   January 2020
Cardiac Output Measurements in Young Children: Reply
Author Notes
  • Children’s Hospital, University Hospital of Lund, Lund, Sweden and Landspítalinn, University Hospital of Iceland, Reykjavik, Iceland. theodorsku@hotmail.com
  • (Accepted for publication September 18, 2019.)
    (Accepted for publication September 18, 2019.)×
Article Information
Correspondence
Correspondence   |   January 2020
Cardiac Output Measurements in Young Children: Reply
Anesthesiology 1 2020, Vol.132, 209-210. doi:https://doi.org/10.1097/ALN.0000000000003022
Anesthesiology 1 2020, Vol.132, 209-210. doi:https://doi.org/10.1097/ALN.0000000000003022
We are thankful for Dr. Morey’s excellent comments regarding possible inaccurate estimates in limits of agreement related to repeated measurements in the same subject with regards of our recent paper.1 
This issue was raised during statistical revision of the paper, where we first presented our results with a Bland–Altman analysis using mean cardiac output values for both methods in all 43 subjects (resulting in only 43 x–y pairs for comparison). As recommended by the statistical reviewer, this was corrected to a Bland–Altman analysis of each repeated measurement (using all 215 x–y pairs), assuming a nonconstant change in cardiac output. This correction did not have any remarkable effect on the limits of agreement (0.41 to –0.24 for 43 x–y pairs and 0.40 to –0.24 for 215 x–y pairs). We then tried to apply the recommended modified Bland–Altman method for repeated measurements2  but for some reason were not able to reach assumed estimates. Instead we used the approach recommended by Zou to estimate limits of agreement3  and found that it was in agreement with our previous limits of agreement estimations (0.40 to –0.25 using Zou’s method for 215 x–y pairs). We had not seen the paper by Myles and Cui4  expanding on the modified Bland–Altman method.