IVC ultrasound

Background

• Though contriversal, IVC measurement by ultrasound can estimate volume status and fluid responsiveness
  • There is moderate evidence to support that IVC diameter is consistently low in hypovolemia vs euvolemia
  • It is suggested that IVC change can estimate fluid responsiveness with a Sn 0.78 and Sp 0.86
• Measure both absolute diameter of IVC and percent collapse during inspiration of spontaneously breathing patients
• Can use as a dynamic assessment after intervention (giving fluids)
• Unclear if applicable to intubated patients

Technique

• Use curvilinear (abdominal) probe or phased array (cardiac) probe
• In subxyphoid cardiac view (epigastric), fan probe laterally to view the IVC draining into the right atrium
  • may start with subxyphoid view, place right atrium in center of screen and rotate probe 90 degrees clockwise to find IVC
  • Use M-mode to measure IVC collapse during inspiration or estimation can be made in 2D with IVC in longitudinal axis

Measurements

IVC	% Collapse during inspiration^	CVP
<1.5cm	>50%	0-5
1.5-2.5cm	>50%	5-10
1.5-2.5cm	<50%	10-15
>2.5cm	Little phasicity	15-20

^Measure ~2cm from IVC/RA junction

• Can ask patient to sniff or valsalva to evaluate collapse

See Also

• Ultrasound (Main)

References

Dawson, M. Mallin, M. Introduction To Bedside Ultrasound: Volumes 1 and 2.Emergency Ultrasound Solutions. 2012 Inkling File