In Reply

We thank Dr. Jacquet-Lagrèze et al. for their interest in our recent article¹  and are happy to respond to their comments.

We fully agree with Dr. Jacquet-Lagrèze et al. on the pivotal value of Standards for Reporting Diagnostic Accuracy Studies²  to improve the quality of diagnostic accuracy studies. As clearly mentioned in the article, inclusions were conducted over a 1-yr period among nonconsecutive patients, and only 28 patients were included. As stated in the Discussion section, we therefore cannot exclude the possibility of selection bias.

We respectfully fully disagree with Dr. Jacquet-Lagrèze et al. when they claimed that the studies cited in the article do not support the rationale to define responders to volume expansion as an increase of stroke volume of 10% or more. We invite the authors to read these recommendations^3,4  carefully and many other publications on the subject.⁵ 

The least significant change has not been yet evaluated for proAQT system (Pulsion Medical Systems, Feldkirchen, Germany). However, the algorithm for pulse contour analysis of the proAQT system is the same as that of the PiCCO system (Pulsion Medical Systems). The main difference between these two devices lies in cardiac output calibration (i.e., transpulmonary thermodilution for the PiCCO and specific algorithm without external method for the proAQT system). Previous studies demonstrated that the proAQT pulse contour analysis algorithm was able to detect changes in cardiac output as small as 5.0% during an end-expiratory occlusion test,⁶  10.0% during a passive leg raising test,⁷  9.5% during a respiratory cycle,⁸  and, even more recently, 6.0% during a mini-fluid challenge.⁹  Although we fully concur with the authors that additional research is warranted, our data remain nevertheless in line with most recent literature.

Finally, we apologize to the authors for having omitted some significant contributions. However, most of them were unavailable at the time of the submission process without, from our point of view, providing added value (postoperative setting, positive end expiratory pressure elevation in septic patients, mean arterial pressure monitoring, pulmonary elimination of carbon dioxide, etc.).