Inferior vena cava dimensions in patients with acute kidney injury
Background: Volume contraction frequently contributes to the development of acute kidney injury. The rapid assessment of volume status in patients with acute kidney injury could improve decision making and outcomes.
Methods: The maximum and minimum diameters and percent collapsibility of the inferior vena cava (IVC) were measured in 30 patients admitted to the medical intensive care unit with laboratory evidence of acute kidney injury. These measurements were made on the day of admission and 24 hours following admission. Information about age, gender, body mass index, serum creatinine levels, and fluid balances was recorded.
Results: This study included 30 patients with a mean age is 62.4 ±16.0 years. The mean initial creatinine was 4.3 ± 4.2 mg/dL (range: 1.7 mg/dL to 22.1 mg/dL). The mean fractional excretion of sodium was 2.06 ± 2.65%. The mean maximum diameter of inferior vena cava was 1.8 ± 0.5 cm with the range is 0.4-2.65 cm. The mean percent collapse was 32 ± 20%. Five patients had evidence of hypovolemia using guidelines from the American Society of Echocardiology; 6 patients had evidence of hypervolemia. Nineteen patients had measurements between these 2 categories. There is no significant change in mean diameters following fluid administration for 24 hours. An initial IVC diameter of 0.94 cm predicted ≥ 30% collapsibility with an area under the curve is 0.748.
Discussion: Patients with acute kidney injury based on laboratory measurements had evidence for hypovolemia, euvolemia, and hypervolemia based on IVC measurements. There was no consistent change in IVC dimensions following fluid administration, even though the creatinine fell in most patients. Simple bedside measurements of IVC dimensions can facilitate fluid administration decisions but must be used with clinical assessment.
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