Reply to: is the central venous pressure an obsolescent model or a valuable puzzle stone in haemodynamic monitoring?
We thank Siegler et al. for their comments on the Guideline ‘Intravascular Volume Therapy in Adults’, published on behalf of the German Association of Scientific Medical Societies by an inter-disciplinary and inter-professional group of authors.1,2 We are glad about the ongoing scientific debate that was and is triggered by this work.
The guideline is strictly focussed on diagnosis and treatment of hypovolaemia. It is based on 248 scientific publications that had to pass a prospectively defined and consented process of literature research, screening for inclusion/exclusion criteria, quality assessment and data extraction before being included into the guideline's evidence base as demanded by the principles of the German Association of Scientific Medical Societies on scientific guideline development.3 About 18 000 articles were screened for inclusion or exclusion. Whenever available, high-grade evidence like systematic reviews, meta-analyses and randomised controlled trials were favoured over low-grade evidence. Narrative reviews, case series or experts opinions and so on were prospectively excluded from the evidence base.
Independent delegates of 14 participating scientific medical societies, further proven experts on methodology and additional clinical experts finally developed six statements and 50 recommendations based on this evidence. During the consensus conferences, the ballots were carried out anonymously with one vote per medical society. Each single statement and 48 of the 50 recommendations obtained agreement by more than 75% of the delegates. The board of each participating society consented to the guideline as a whole. However, the board of one single society disagreed with four specified recommendations. Finally, the board of the German Association of Scientific Medical Societies consented to the content and process of this evidence-based guideline.
The methodologically compelling, strictly evidence-based development of the guideline resulted in a high degree of consensus obtained among both the delegates and the societies’ boards. It also resulted in a guideline that is strictly focussed on diagnosis and treatment of hypovolaemia. In addition, finally it created a sound and robust guideline that both results from and contributes to evidence-based medicine.
Basically, Siegler et al. criticise two strong recommendations (grade of recommendation A, both), namely not to use central venous pressure for diagnosis of hypovolaemia and to use a monitoring method that allows the estimation of volume responsiveness for fluid management, with flow-based or dynamic preload variables being superior to static variables in this regard. The authors are concerned that clinicians may abandon central venous pressure measurement to comply with the guideline's recommendations. They emphasise that central venous pressure measurement is a valuable puzzle stone in haemodynamic monitoring. They argue that there is a general lack of consensus among clinicians regarding central venous pressure measurements.
Again, the validity of the guidelines’ recommendations is restricted to the diagnosis and treatment of hypovolaemia, as they do not apply to other clinical situations. Regarding hypovolaemia and speaking methodologically, the concerns of Siegler et al. are experts’ opinions and thus inferior to the group of systematic reviews, meta-analyses and randomised controlled trials that the guideline is based upon. Furthermore, this opinion is in contrast to the consented appraisal of both delegates and boards of 14 national medical societies.
Finally, we would like to respond to the author's arguments in detail.