24-13: Subxiphoid Long-Axis (IVC)

Technique

• The transducer indicator is directed toward the patient’s feet.

• The transducer is placed subxiphoid in a midline plane and tilted toward the patient’s right to identify the IVC as it enters the right atrium (Fig. 24.46).

• Identify the liver, IVC, right atrium, and right hepatic vein (Fig. 24.47).

• Measure the IVC 2 to 3 cm caudal to the entry point to the right atrium. Measure the IVC through the respiratory cycle at end inspiration and expiration (Fig. 24.48).

Abnormal Findings

• IVC collapse: The IVC should partially collapse during the normal respiratory cycle in nonventilated patients. A totally collapsed IVC is indicative of low central venous pressure (CVP). More than 50% collapse is less specific but also indicative of low CVP (Fig. 24.49).

• IVC size: The size of the IVC may be measured throughout the respiratory cycle. In general, an IVC that measures 2 cm or greater with poor respiratory variation is indicative of elevated CVPs due to volume overload, RV failure, and/or tamponade physiology (Fig. 24.50A,B).

• IVC distensibility: In patients receiving positive-pressure ventilation, the IVC will distend rather than collapse during inspiration. Measurements of IVC distensibility in ventilated patients can be used to calculate volume responsiveness to intravenous fluid challenge.