To compare cardiac index (CI) between Proaqt/PulsioFlex^® and oesophageal Doppler (OD) and the ability of the PulsioFlex^® to track CI changes induced by fluid challenge and secondly to assess the impact of the time interval between two auto-calibrations of PulsioFlex^® on the accuracy of the measured CI.

In a single hospital, 49 intermediate-risk oncologic abdominal surgery patients were included in an observational study. We measured the cardiac Index (CI) provided by OD and by the Proaqt/PulsioFlex^® before and after internal calibration, which were performed randomly at specific intervals after the initial one (30, 60, 90 and 120min). The ability to track fluid responsiveness was evaluated by measuring stroke volume variation, pulse pressure variation (PPV) and CI before and after a 250ml fluid challenge and assessed by a receiver operating characteristic curve analysis.

The percentages of error before calibration were 51, 58, 82, 81% for 30, 60, 90 and 120min, they were 39, 57, 65, and 54% after calibration. Trending ability is assumed by a 93% concordance rate after applying a 15% exclusion zone. The trend interchangeability rate was 13.75%. The area under the curve for fluid responsiveness measured by PPV and SVV PulsioFlex were respectively 0.67 [0.57–0.77], P<0.01 and 0.75 [0.47–0.66], which was not clinically relevant.

The Proaqt/Pulsioflex^® system is not equivalent to OD for haemodynamic monitoring during non-vascular abdominal surgery in intermediate-risk patients. More studies are required to define the effect of the auto-calibration on the system.