Table 1.

Review of the methods used for measurement of the cross-sectional area and the velocity of the internal jugular vein.

Reference	CSA measurment	Velocity measurment
Sisini et al. (Sisini, et al. 2015)	manually drawn circumference	TAV over 4 cardiac cycles
Ozen et al. (Ozen, et al. 2014)	D/2*π in longitudinal plane	mean TAV over 2–3 cardiac cycles
Jakimovski et al. (Jakimovski, et al. 2017)	manually drawn circumference	mean TAV over 4 seconds
Yeoh et al. (Yeoh, et al. 2017)	manually drawn circumference	mean TAV over 3 seconds
Chambers et al. (Chambers, et al. 2014)	D/2*π in longitudinal plane	mean TAV over 4–5 cardiac cycles
Schreiber et al. (Schreiber, et al. 2003)	D/2*π in transverse plane	not described
Monti et al. (Monti, et al. 2011)	manually drawn circumference	TAV over 3 cardiac cycles at end of expiration
Ciuti et al. (Ciuti, et al. 2013)	D/2*π in transverse plane	Quality Doppler Profiles (QDP) velocity

CSA – cross-sectional measurement, D – diameter, TAV – time averaged velocity