Ultrasound Assessment of the Inferior Vena Cava for Fluid Responsiveness: Making the Case for Skepticism

Abstract

Determining whether a patient in shock is in a state of fluid responsiveness (FR) has long been the Holy Grail for clinicians who care for acutely ill patients. While various tools have been put forth as solutions to this important problem, ultrasound assessment of the inferior vena cava has received particular attention of late. Dozens of studies have examined its ability to determine whether a patient should receive volume expansion, and general enthusiasm has been strengthened by the fact that it is easy to perform and non-invasive, unlike many competing FR tests. A deeper examination of the technique, however, reveals important concerns regarding inaccuracies in measurement and a high prevalence of confounding factors. Furthermore, a detailed review of the evidence (small individual studies, multiple meta-analyses, and a single large trial) reveals that the tool performs poorly in general and is unlikely to be helpful at the bedside in circumstances where genuine clinical uncertainty exists.

Assessing Fluid Intolerance with Doppler Ultrasonography: A Physiological Framework

“…Considering the aforementioned, while it is tempting to infer that inspiratory IVC collapse and/or a normal ejection fraction necessarily indicate IV fluids in circulatory failure, these assumptions can be wrong. Inspiratory IVC collapse has multiple co-varying determinants, including changing pleural, abdominal and central venous pressures [ 29 , 30 , 31 , 32 ]. Assuming that the pleural and abdominal pressures change consistently (within a patient and between patients) then the primary hemodynamic determinant of IVC collapse is the right atrial pressure or CVP [ 33 ].…”

Inferior Vena Caval Measures Do Not Correlate with Carotid Artery Corrected Flow Time Change Measured Using a Wireless Doppler Patch in Healthy Volunteers

“…This small, pilot study cannot explain the underlying mechanism of this observation, though the inspiratory collapse of the IVC is driven by multiple determinants, only one of which is the pressure within the vein. Subtle differences in blood volume, inspiratory pattern, abdominal compliance and the distribution between portal and non-portal venous return may mediate the size and collapse of the IVC [18,[43][44][45][46][47][48][49][50][51][52]. The dissociation between the IVC collapse and ccFT ∆ is clinically relevant, as measuring ccFT ∆ ostensibly improves the sensitivity of IVC collapse for predicting fluid responders.…”

Dynamic monitoring tools for patients admitted to the emergency department with circulatory failure: narrative review with panel-based recommendations

“…In addition, cardiac factors, most importantly right ventricular dysfunction, can also confound the results; such patients typically have a chronically dilated IVC which renders interpretation difficult [23]. Moreover, USs do not allow real-time continuous monitoring [23], and the collapsibility and diameter thresholds have not been validated in critically ill patients [24]. [25] reported that baseline SV and CO were better at predicting the response to fluid resuscitation than traditional markers.…”