POLECAT: Perioperative Delta Renin Concentration

The renin-angiotensin system (RAS) plays a key role in haemodynamic stability, vascular tone and electrolyte homeostasis. It is recognised that this system is dysfunctional during critical illness. It remains unknown as to whether significant dysfunction of RAS is found in patients who have undergone major abdominal surgery - however over 50% of these patients often require blood pressure support post-operatively, with nearly half of these patients having unexplained drops in blood pressure.

Renin represents an attractive biomarker that could be implicated in post operative vasoplegia and post operative AKI and as such elevated renin concentrations could be used to identify high-risk patients for cardiovascular instability and AKI who would benefit from timely intervention that could improve their outcomes, this would include the use of selective vasopressor agents such as angiotensin II which has been shown to confer a benefit in patients with underlying dysregulation of the RAS.

If we show that higher differences in renin concentrations are associated with a greater incidence of vasoplegia then we can design a subsequent clinical trial with a different treatment in those who have a higher change in renin. Such a trial is currently recruiting in Germany for patients with higher changes in renin due to cardiac surgery.

The primary aim is to assess whether there is an association between higher differences in renin concentrations (a protein that can be measured in your blood) and haemodynamic instability manifest as vasoplegia (patients exhibiting low blood pressure) in patients undergoing major abdominal surgery requiring post-operative admission to ICU.