Mean arterial pressure and central venous pressure difference as a prognostic tool for postoperative acute kidney injury 


Background and Goal of Study: Postoperative acute kidney injury (AKI) remains a serious complication of surgery. Recent findings suggest the role of venous congestion in generating AKI; indeed, it has been demonstrated that a high CVP is detrimental on the kidney function, in particular when associated with hypervolemia. Of note, also an impairment of the arterial intrarenal perfusion pressure increase the risk of AKI. Thus, it is reasonable that both low arterial pressure and high CVP contribute to renal congestion. The aim of this study in to evaluate if the difference between mean arterial pressure (MAP) and CVP can predict postoperative AKI.
Materials and Methods: 
This is a prospective-observational study conducted at Sant’Anna Hospital, Ferrara. All patients >18 years undergoing abdominal surgery requiring central venous catheter were enrolled. We collected clinical, demographic and laboratory data for each patient. All potentially nephrotoxic drugs were recorded. Moreover, we measured MAP-CVP difference at the end of surgery, 24h and 48h after surgery. Occurrence of AKI was defined according to KDIGO criteria.
Results and Discussion: Fifty-one patients were enrolled. Clinical and demographic variable are shown in Figure 1. Postoperative AKI occurs in 9 of 51 patients (18%). Patients who developed AKI had significantly lower MAP-CVP difference. Potentially modifiable risk factor for postoperative AKI were use of NSAIDs and aminoglycosides. 
Conclusion(s): MAP-CVP difference at the end of surgery is a prognostic factor for postoperative AKI even in patients with a similar intraoperative fluid balance. Fluid administration during and after surgery should take into account the effect on CVP and arterial pressure.
References: Cruces, ICM 2014