In the German guidelines on intra-operative haemodynamic management, we emphasise that 'even in fluid-responsive patients, the indication for fluid administration should be determined individually based on haemodynamics and clinical context'. Being 'fluid responsive' is a normal physiological state and does not necessarily indicate that a patient requires fluids. The Frank-Starling mechanism does not illustrate a causal relationship where an increase in cardiac preload (as an independent variable) leads to a subsequent increase in cardiac output (as a dependent variable). Rather, the evolutionary purpose of the Frank-Starling mechanism is to match cardiac output to variations in venous return caused by exercise or changes in posture. Clinicians should not routinely attempt to maximise stroke volume or cardiac output by giving fluids in patients having surgery because it is unlikely that surgical patients require their maximal cardiac output, as energy expenditure during major surgery with general anaesthesia is roughly one quarter lower than resting awake energy expenditure. In summary, clinicians should not routinely give repeated fluid boluses simply to use the full preload reserve in patients having major noncardiac surgery. Decisions to give - or not give - fluids must incorporate considerations that extend far beyond the physiological condition of 'fluid responsiveness'.

Peri-operative medicine is a critical component of contemporary healthcare delivery. Despite significant advancements, peri-operative complications remain a relevant concern. Obtaining reliable risk estimates, identifying potential causes, and studying new interventions, revised policies or implementation of best practices to prevent complications, requires data from a large number of participants. Electronic Patient Record systems offer the opportunity to unlock these data, but the limited standardisation of databases and sharing frameworks available across Europe limit the effective use of the available data. We propose creating a European peri-operative shared data registry with continuous data collection, integrating clinical, bedside monitoring and outcome data in a collaborative network. Such network would facilitate outcomes research, could serve as a platform to optimise clinical practices by fostering quality improvement through benchmarking of care delivered by departments or individual physicians, and could be used to evaluate policy changes. This ESAIC initiative aligns well with the development of the European Health Data Space. This article provides examples of contemporary clinical research and practice evaluation questions to illustrate the need for a European collaborative data-sharing network, highlights inspiring examples of existing data-sharing initiatives and describes a road map to establish such network.

Acute kidney injury (AKI) is a common complication after surgery. Greater fluid administration has been related to an increased incidence in patients undergoing major surgery but there are no large series of patients in specific perioperative settings showing relationship between fluid balance and the occurrence of AKI. This study tested the hypothesis that higher perioperative fluid balance was associated with an increased risk of postoperative AKI. Prospective observational study. Predefined secondary sub-study of the Postoperative Outcomes Within Enhanced Recovery After Surgery (POWER) study. A pre-planned secondary analysis of a multicentre study in 80 hospitals in Spain during a single period of 2 months of recruitment between September and December 2017. Patients undergoing elective primary colorectal surgery with a planned overnight stay were included if they had complete data regarding postoperative fluid balance. Patients who underwent urgent or emergency surgery or with estimated glomerular filtration rate less than 30 ml min -1 were excluded. The primary outcome was the occurrence of AKI (mild, moderate, or severe) at 30 days following surgery. AKI was defined according to KDIGO and EPCO guidelines, incorporating serum creatinine and urine output criteria. A total of 1139 patients were included in the study. Of these, 73 patients (6.4%) developed acute kidney injury in the postoperative period. The adjusted relative risks (RR) that compared the quartile with the lowest perioperative fluid balance (Q1) with other quartiles were 4.10 [95% confidence interval (CI), 1.60 to 10.51] for Q3 and 4.81 (95% CI, 1.91 to 12.11) for Q4. In the Poisson loglinear model after adjusting by sex, ASA grade, Enhanced Recovery After Surgery (ERAS) adherence and intraoperative bleeding, RR for AKI were higher with a higher positive perioperative fluid balance (quadratic nonlinear P < 0.01). In this secondary analysis, we found that higher positive perioperative fluid balance during the first 24 h was associated with an increased risk of postoperative acute kidney injury in patients undergoing elective colorectal surgery. Clinicaltrials.com identifier: NCT03012802.