Echography of the inferior vena cava for estimating fluid removal from patients undergoing hemodialysis.

Echography was used to perform 118 consecutive measurements of the diameters of the inferior vena cava (IVC) in 28 chronic hemodialysis patients. There was a significant correlation between the percent changes in the IVC in the expiratory phase (dIVC-E) and the percent changes in body weight (dBW) (r = 0.620, p < 0.002, n = 118). The average IVC diameter in the expiratory phase before dialysis (IVC-E) was 15.3 +/- 4.6 mm and this value decreased gradually following ultrafiltration and reached an average diameter of 11.0 +/- 4.3 mm after dialysis. Three cases developed hypotension due to fluid removal. Their IVC-E value showed a rapid reduction below 11.0 mm in the early phase of hemodialysis, then maintained a plateau. The hypotension was attributed to hypovolemia due to excessive dehydration. Our results suggest that the IVC-E diameter in postdialysis would approach 11.0 +/- 4.3 mm, which could be interpreted as being close to the dry weight.