[A pilot study of measuring inferior vena cava internal diameter on transverse section plane in different sites by...

To investigate the shape change index (SCI) of inferior vena cava (IVC) measured from subcostal area and right mid-axillary line through ultrasonography laying the foundation for future research about SCI and volume status.

A total of 107 patients were enrolled in the Critical Care Medicine Department of Peking Union Medical College Hospital from December, 2014-January, 2015. The maximal diameter (MXD) and the minimal diameter (MID) were measured transversely from subcostal area and right mid-axillary line. The SCI was calculated.

Totally 47 patients (42 with spontaneous breathing and 5 on mechanical ventilation) achieved measurements on transversal plane from subcostal area and right mid-axillary line. (1) The internal diameter of IVC on longitudinal plane measured from subcostal area was statistically different from that measured from right mid-axillary line both at end inspiration (P=0.001) and at end expiration (P=0.027). (2) No difference were found in the SCI measured from subcostal and right mid-axillary line both at end inspiration and at expiration. (3) The internal diameter of IVC and the SCI measured on transversal plane from subcostal area correlated well with that measured from mid-axillary line both at end inspiration (SCI:r=0.866, P=0.000) and at end expiration (SCI: r=0.887, P=0.000).

Inferior vena cava internal diameters and the shape change index measured through ultrasonography on transversal planefrom subcostal area are correlated well with those from mid-axillary line. Measurements from the two sites can be replacedby each other.