IVC ultrasound
Background
- Inferior vena cava measurement by ultrasound to estimate volume status
- 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
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
References
Dawson, M. Mallin, M. Introduction To Bedside Ultrasound: Volumes 1 and 2.Emergency Ultrasound Solutions. 2012 Inkling File