Inferior Vena Cava/Aorta Diameter Index for the Evaluation of Intravascular Volume Status in Children with Idiopathic Nephrotic Syndrome.

OBJECTIVES

To correlate the inferior vena cava/aorta diameter (IVC/Ao index) in children with nephrotic syndrome with clinical indicators of volume status, and to compare the IVC/Ao index between children in relapse and in remission.

METHODS

This prospective longitudinal study included children aged 2-18 years presenting with relapsed nephrotic syndrome. Low intravascular volume status was diagnosed if two of the three criteria (tachycardia, hypotension, prolonged capillary filling time) were present. Sonographic measurements of the IVC and aorta diameter were obtained by a single observer at recruitment and after achieving remission.

RESULTS

One hundred and three children (73 boys) with a median (Q1, Q3) age 72 (24, 216) months were recruited. 26 (25%) children had low intravascular volume at recruitment. The mean (SD) IVC/Ao index was lower in low volume status compared to normal volume status [0.74 (0.2) vs 0.83 (0.1); P = 0.090]. The correlation between IVC/Ao index and heart rate (r = -0.29, P = 0.003) and mean arterial pressure (r = 0.23, P = 0.018) was weak. IVC/Ao index was not an independent predictor of volume status (OR = 0.04, P = 0.331). The mean (SD) IVC/Ao index increased significantly from when in relapse to remission [0.94 (0.1) vs 1.05 (0.2), respectively; P = 0.001].

CONCLUSIONS

The IVC/Ao index was lower in relapse than in remission, and did not predict low intravascular volume status independently.