Agreement between continuous noninvasive finger cuff-derived and invasive arterial blood pressure measurements: Effect of data sampling and data processing.

BACKGROUND

The effect of different methods for data sampling and data processing on the results of comparative statistical analyses in method comparison studies of continuous arterial blood pressure (AP) monitoring systems remains unknown.

OBJECTIVE

We sought to investigate the effect of different methods for data sampling and data processing on the results of statistical analyses in method comparison studies of continuous AP monitoring systems.

DESIGN

Prospective observational study.

SETTING

University Medical Center Hamburg-Eppendorf, Hamburg, Germany, from April to October 2019.

PATIENTS

49 patients scheduled for neurosurgery with AP measurement using a radial artery catheter.

MAIN OUTCOME MEASURES

We assessed the agreement between continuous noninvasive finger cuff-derived (CNAP Monitor 500; CNSystems Medizintechnik, Graz, Austria) and invasive AP measurements in a prospective method comparison study in patients having neurosurgery using all beat-to-beat AP measurements (Methodall), 10-s averages (Methodavg), one 30-min period of 10-s averages (Method30), Method30 with additional offset subtraction (Method30off), and 10 30-s periods without (Methodiso) or with (Methodiso-zero) application of the zero zone. The agreement was analysed using Bland-Altman and error grid analysis.

RESULTS

For mean AP, the mean of the differences (95% limits of agreement) was 9.0 (-12.9 to 30.9) mmHg for Methodall, 9.2 (-12.5 to 30.9) mmHg for Methodavg, 6.5 (-9.3 to 22.2) mmHg for Method30, 0.5 (-9.5 to 10.5) mmHg for Method30off, 4.9 (-6.0 to 15.7) mmHg for Methodiso, and 3.4 (-5.9 to 12.7) mmHg for Methodiso-zero. Similar trends were found for systolic and diastolic AP. Results of error grid analysis were also influenced by using different methods for data sampling and data processing.

CONCLUSION

Data sampling and data processing substantially impact the results of comparative statistics in method comparison studies of continuous AP monitoring systems. Depending on the method used for data sampling and data processing, the performance of an AP test method may be considered clinically acceptable or unacceptable.