Analysis of online gas monitoring CDI 500® and SYSTEM M-M4®. Are they comparable tools for clinical perfusion practice?

Objective: to compare the data obtained from the CDI500® and Spectrum M4® to assess the reliability of the results and their impact on cardiopulmonary bypass. Methods: a prospective observational study of patients undergoing cardiac surgery with CPB was conducted between January-2017 and February-2018. The data provided by CDI and M4 was collected. Arterial and venous blood gases taken from Radiometer ABL90 Flex® were used as control. With the first sample, the data of both analyzers were adjusted. A minimum of two samples and a maximum of four were made. Results: 100 patients and 292 samples (32% women) with a mean age of 65.2 ± 11.5 years were studied. The parameters of the CDI and M4 practically did not present significant differences after the first adjustment, and without affecting the clinical practice, except in the bicarbonate and the excess of base where CDI does not adjust to the values. The analysis was done with the Bland/Altman charts, the PCO2 and PO2 were better measured by the CDI while Hto, Hb and SvO2 by M4, which was corroborated comparing the error percentages less than ± 5% in both systems, the significant differences being in the five parameters. Conclusions: both systems provide reliable data, although they require a previous calibration. The M4 allows direct evaluation of data to help a goal directed perfusion.