Peripheral Edema, Central Venous Pressure, and Risk of AKI in Critical Illness

Abstract

Background and objectives: Although venous congestion has been linked to renal dysfunction in heart failure, its significance in a broader context has not been investigated.

Design, setting, participants, & measurements: Using an inception cohort of 12,778 critically ill adult patients admitted to an urban tertiary medical center between 2001 and 2008, we examined whether the presence of peripheral edema on admission physical examination was associated with an increased risk of AKI within the first 7 days of critical illness. In addition, in those with admission central venous pressure (CVP) measurements, we examined the association of CVPs with subsequent AKI. AKI was defined using the Kidney Disease Improving Global Outcomes criteria.

Results: Of the 18% (n=2338) of patients with peripheral edema on admission, 27% (n=631) developed AKI, compared with 16% (n=1713) of those without peripheral edema. In a model that included adjustment for comorbidities, severity of illness, and the presence of pulmonary edema, peripheral edema was associated with a 30% higher risk of AKI (95% confidence interval [95% CI], 1.15 to 1.46; P<0.001), whereas pulmonary edema was not significantly related to risk. Peripheral edema was also associated with a 13% higher adjusted risk of a higher AKI stage (95% CI, 1.07 to 1.20; P<0.001). Furthermore, levels of trace, 1+, 2+, and 3+ edema were associated with 34% (95% CI, 1.10 to 1.65), 17% (95% CI, 0.96 to 1.14), 47% (95% CI, 1.18 to 1.83), and 57% (95% CI, 1.07 to 2.31) higher adjusted risk of AKI, respectively, compared with edema-free patients. In the 4761 patients with admission CVP measurements, each 1 cm H2O higher CVP was associated with a 2% higher adjusted risk of AKI (95% CI, 1.00 to 1.03; P=0.02).

Conclusions: Venous congestion, as manifested as either peripheral edema or increased CVP, is directly associated with AKI in critically ill patients. Whether treatment of venous congestion with diuretics can modify this risk will require further study.

Keywords: acute kidney injury; acute renal failure; central venous pressure; comorbidity; critical illness; edema; heart failure; humans; pulmonary edema; renal function.

Figure 1.

Incidence of AKI severity according to peripheral edema severity.

Figure 2.

Forest plot for risk of peripheral edema and AKI per subgroup. Adjusted for age, gender, race, intensive care unit type, Sequential Organ Failure Assessment, history of diabetes, congestive heart failure, hypertension, chronic pulmonary disease, peripheral vascular disease, and 24 additional Elixhauser comorbidities, admission vitals (systolic and diastolic BP, heart rate, temperature), admission creatinine, preillness medication usage (angiotensin inhibitor converting enzyme-inhibitor, angiotensin receptor blocker, statin, calcium channel blocker, and diuretics), and pulmonary edema (excluded in pulmonary edema stratification). eGFR calculated from admission serum creatinine concentration using the Modified Diet in Renal Disease equation.