Echography of inferior vena cava for estimating fluid removed from patients undergoing hemodialysis

Twenty-eight chronic hemodialysis patients were studied, and 118 consecutive measurements of the diameter of their inferior vena cava (VCD) were performed with ultrasonography. There was a significant correlation between the percent change in VCD in the expiratory phase (delta VCD-E%) and the percent change of in body weight (delta BW%). The average VCD-E in predialysis was 10.7 +/- 3.2 mm/m2 and this value decreased gradually following ultrafiltration and reached a minimal diameter of 7.5 +/- 2.8 mm/m2 in postdialysis. Three cases developed hypotension due to fluid removal. Their VCD-E value showed a rapid reduction below 7.5 mm/m2 in the early phase of hemodialysis, then maintained a plateau. The hypotension was thought to be caused by hypovolemia due to overdehydration. We conclude that VCD-E was an effective indicator for determining the volume of fluid removed, and the dry weight was attained safely and correctly by means of undergoing ultrafiltration to keep the value of VCD-E above 7.5 +/- 2.8 mm/m2.