We are all familiar with the RUSH exam (see Dr. Weingart’s original article if you’re not). Since it’s been a recurring theme this week, we are going to focus on the IVC measurement of the spontaneously breathing patient. This will not be a discussion of which method of volume status measurement is superior (i.e. leg raise vs ultrasound vs. fluid challenge). Feel free to debate that among yourselves and let me know how it goes.
So where do you measure the IVC? The IVC should be measured just superior to the influx of the hepatic vein ~2 cm from the RA / IVC junction. Dr. Weingart’s article uses a diameter of less than 15 mm with complete IVC collapse as marker for incomplete resuscitation. Similarly a diameter of 25 mm with no inspiratory variation represents a higher CVP that will not likely respond to further fluid challenges.
Obviously this leaves a dubious middle ground. In this range, you may have to employ multiple methods and frequent re-measurements of IVC diameter to help guide your efforts.
While this method is not perfect, it should give you a good starting point to guide your further resuscitation.
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Kircher BJ, Himelman RB, Schiller NB. Noninvasive estimation of right atrial pressure from the inspiratory collapse of the inferior vena cava. Am J Cardiol. 1990;66:493-496.
Simonson JS, Schiller NB. Sonospirometry: A new method for noninvasive estimation of mean right atrial pressure based on two-dimensional echographic measurements of the inferior vena cava during measured inspiration. J Am Coll Cardiol. 1988;11:557-564
Weingart, Scott. Original Rush Article. Emcrit.org http://emcrit.org/rush-exam/original-rush-article/ (accessed 08/19/16)