29.06 Image Related Factors Important for AKI Risk Assessment After Colectomies

E. T. Chang1, A. Lussiez1, J. Li1, N. Wang1, S. C. Wang1  1University Of Michigan,General Surgery,Ann Arbor, MI, USA


Acute kidney injury (AKI) occurs in approximately 20% of hospitalized adults and costs the US $10 billion annually. Prolonged hospital stay, cost, and mortality have been shown to be increased in these patients and those requiring renal replacement therapy have an even higher mortality rate. In the setting of colon surgery, a recent large scale study found several associated factors with postoperative AKI including advanced age, chronic renal failure, and total colectomy. However, a surgical decision informed by standard clinical data alone may not be sufficient. We set out to study the relationship between AKI and quantitative kidney morphomic factors from cross-sectional preoperative imaging for patients undergoing colectomies and comparing the results with demographic and intra-operative data. We hypothesized that individualized kidney characteristics would correlate with the risk of postoperative AKI development.

A retrospective review of prospectively gathered data from adult patients undergoing colectomies from 2006-2012 at the University of Michigan was conducted. 390 initial subjects without elevated baseline creatinine values, ESRD, a prior nephrectomy, or renal injury were included. Polycystic kidneys or other kidney abnormalities identified on imaging were excluded resulting in 326 subjects. AKI was defined by the KDIGO criteria within 30 days of injury. Demographic and intraoperative factors were evaluated along with measurements of pertinent kidney morphomic data including volume, surface area, and average Hounsfield Units (HU) which were subjected to univariate analyses. 

Of the 326 patients, 60 developed AKI (18.4%). Of demographic factors, advanced age (p=0.0002) and a higher BMI (p=0.02) were associated with AKI. Comorbidities associated with AKI included hypertension (p=0.008) and diabetes (p=0.013). Interestingly, intraoperative factors including surgical time (p=0.13), blood transfusions (p=0.14), blood loss (p=0.42), and hypotensive episodes (p=0.17) were not significantly associated with AKI. Table 1 shows the results of the univariate analysis of the morphomic factors.

AKI is a serious complication and the prevalence after colorectal surgery at our institution was 18.4%. Our analysis shows that a lower average parenchymal HU was the most significant morphomic factor associated with postoperative AKI. This study is the first to provide information that morphomic analysis can be useful in clinical practice to determine which patients are at risk for developing AKI after a colectomy.