Associations between mean systemic filling pressure and acute kidney injury: An observational cohort study following cardiac surgery

Abstract

Background Venous congestion has been implied in cardiac surgery‐associated acute kidney injury (CSA‐AKI). The mean systemic filling pressure may provide a physiologically more accurate estimate of renal venous pressure and renal perfusion pressure but its association with CSA‐AKI has not been reported. Methods Patients admitted to ICU following cardiac surgery without pre‐operative renal dysfunction were included with monitoring of mean arterial pressure (MAP) and central venous pressure (CVP) and cardiac output (CO) to calculate the mean systemic filling pressure analogue (Pmsa). The AKI‐KDIGO guidelines were used to define CSA‐AKI. Logistic regression models including CO, heart rate, MAP, CVP and Pmsa were used to ascertain the association with CSA‐AKI and reported by odds ratio (OR) with 95% confidence interval (95%CI) and area under the curve (AUROC). Results One hundred and thirty patients (out of 221 screened) were included of whom 66 (51%) developed CSA‐AKI. Patients with CSA‐AKI were older, with greater weight and increased stay in ICU while the proportion of comorbidities, type of surgical procedures, APACHE III scores and fluid volumes administered were similar to patients without AKI. The Pmsa, but not CVP, was associated with CSA‐AKI (OR 1.2 95%CI [1.16‐1.25]). Renal perfusion pressure was associated with CSA‐AKI estimated as MAP‐Pmsa (OR 0.81 [0.76‐0.86]) and MAP‐CVP (OR 0.89 [0.85‐0.93]) with the former generating a higher AUROC (median difference 0.10 [0.07‐0.12], P < .001) in the regression model. Conclusions The Pmsa in post‐operative cardiac surgery patients was associated with the development of CSA‐AKI also when incorporated into estimates of renal perfusion pressure.

The impact of relative hypotension on acute kidney injury progression after cardiac surgery: a multicenter retrospective cohort study

“…Greater relative hypotension was caused by higher preoperative or lower postoperative MPP, while smaller relative hypotension was caused by lower preoperative or higher postoperative MPP. Since previous studies [ 16 , 17 , 38 ] and our study have consistently shown that lower postoperative MPP is a risk factor of AKI, the non-linear relationship between preoperative MPP and AKI progression could weaken the association between relative hypotension and AKI progression. Higher preoperative MPP could increase the risk of AKI due to the right shift in the lower pressure limit of renal autoregulation in the presence of chronic hypertension [ 14 ].…”

“…Mean perfusion pressure (MPP), which is the difference between MAP and central venous pressure (CVP), can also be used as a surrogate marker for renal perfusion because elevated CVP has been reported as a risk factor for AKI in ICU patients [ 13 , 14 ]. Although CVP monitoring is readily available in patients after cardiac surgery [ 15 ], few studies have assessed the relationship between MPP and AKI in this population [ 16 , 17 ].…”

Changes in the venous return system and mortality in patients with constrictive pericarditis after pericardial stripping: a retrospective cohort study

“…We found that the difference in Pmsf − CVP between 48 hours and the time of admission was positively correlated with total negative uid balance at 48 hours, suggesting a gradual decrease in the differential venous return driving pressure in patients with negative uid balance. Regarding the relationship between venous return and organ function, a study comparing MAP − CVP and MAP − Pmsf found that MAP − Pmsf correlated better with acute kidney injury and better represented the backward pressure of renal perfusion pressure [43]. Pmsf is an upstream indicator of venous return.…”

Assessing the association between mean systemic filling pressure and acute kidney injury after cardiac surgery

“…With a great interest we read the recent article by Neuman et al 1 assessing the association between mean systemic filling pressure analogue (P msa ) and acute kidney injury (AKI) following cardiac surgery. They showed that P msa as a surrogate for renal venous pressure was more closely associated with postoperative AKI than central venous pressure.…”