Inferior vena cava ultrasonography could predict acute kidney injury in critically ill patients

Context: Acute kidney injury (AKI) is a complication frequently encountered in critically ill patients and is associated with poorer outcomes. Bedside ultrasonographic assessment (POCUS) has proven to be a valuable tool for noninvasively assessing hemodynamic status. However, few studies evaluate the usefulness of inferior vena cava (IVC) measurements of acute kidney injury management among critically ill patients. Objective: This study aimed to address this gap in knowledge by evaluating the effectiveness of inferior vena cava measurements and their relationship with acute kidney injury management in critically ill patients. Methodology: Patients admitted to the intensive care unit (ICU) were selected and underwent daily bedside ultrasonographic assessment to monitor the inferior vena cava. The collapsibility index (IC IVC [%] = Dmax - Dmin] / Dmax) was calculated, and a cutoff point of <20% was established to define the absence of hypovolemia (no volume response). B-mode measurements of the transverse axis of the long (Ld), short (Sd) diameter, and inferior vena cava area at the maximum and minimum time were also performed, and calculations were made. As a result, the development of acute kidney injury and its severity were determined according to the KDIGO classification. Results: The increase in daily cumulative balance was associated with acute kidney injury (620 +1,116 mL vs 115 +816 mL,16; P=0.001), with no differences in the daily amount of liquids administered for both groups (1,841 +1,071 vs 1,602 +1,602; P=0.1444). During daily follow-up, in the acute kidney injury group an increase in both maximum (Dmax) and minimum (Dmin) inferior vena cava diameters was associated with greater acute kidney injury severity according to KDIGO criteria (Dmax Coef. 0.187 - Dmin Coef. 0.160, P>|Z|: 0.008 - 0.006, CI >95% [0.049 / 0.324] - [0.046 / 0.273]). This association was particularly notable in patients admitted post cardiovascular surgery (n=14, Coef. 0.761, P > | | Z |: 0.005, CI > 95% [0.229 / 1.292]). Conclusions: Serial longitudinal and transverse axis bedside ultrasonographic assessment measurements of the inferior vena cava can help predict the severity of acute kidney injury in critically ill patients, especially in postoperative cardiovascular surgery patients.