ECC Suggested Readings
December 2025
Wan-Chu (Ellan) Hung DVM, MS, DACVECC
I am originally from Taiwan and I am currently a Clinical Assistant Professor in Small Animal Emergency and Critical Care at the University of Florida. I enjoy teaching students and house officers in the clinical setting and value opportunities to contribute to scientific advancement in veterinary medicine. Outside of work, I love trying new recipes and spending time with my Great Dane and two cats.
A paper that I recently liked…
A Prediction of Fluid Responsiveness Based on the External Jugular Vein Distensibility Index After Changes in Volume Status in Healthy, Anesthetized, and Mechanically Ventilated Dogs
Seo D, Lim S, Namgoong B, Uhm H, Hong H, Lee N, Kim I, Heo S, Kang JH, Kim C, Shin H, Her J, Kim MS
Paper Commentary
The study design
This study was a prospective, non-randomized experimental study evaluating the utility of a novel variable, the external jugular vein distensibility index (EJVDI), for predicting fluid responsiveness in dogs. Six healthy dogs were anesthetized, mechanically ventilated, and subjected to serial controlled changes in intravascular volume status through blood removal, staged autotransfusion, and saline administration to induce fluid overload. Point-of-care ultrasound (POCUS) was used to obtain EJVDI measurements, and fluid responsiveness (FR) was defined as > 15% increase in left ventricular outflow tract velocity time integral (VTI) after a fluid challenge. Additional static and hemodynamic variables were recorded after each volume change and compared with EJVDI and VTI responses.
The study background
Fluid therapy is essential in critical care medicine, particularly in the management of hypovolemia. However, accurately assessing a patient’s volume status and predicting fluid responsiveness can be challenging. Inappropriate or excessive fluid administration can lead to significant complications. Traditional static variables, including central venous pressure (CVP), mean arterial pressure (MAP), and heart rate (HR), have proven to be unreliable in predicting fluid responsiveness. Dynamic variables such as pulse pressure variation (PPV), systolic pressure variation (SPV), and caudal vena cava collapsibility index (CVCCI) offer better predictive accuracy but often require advanced technical skills or more invasive monitoring. The external jugular vein, being larger and more accessible in dogs, was therefore proposed as a practical candidate for ultrasound-based assessment of fluid responsiveness.
Study considerations
I think this was a well-designed and well-executed experimental study, and the findings were compelling. EJVDI demonstrated strong diagnostic performance, with an AUROC of 0.92 and a cutoff value of 22.7% distinguishing fluid responders from non-responders. It also correlated well with established dynamic variables such as PPV and SPV and appropriately reflected changes in volume status. The authors also incorporated a gray zone approach to AUROC interpretation, allowing cases with intermediate values to be identified and prompting additional assessment, which more closely mirrors real clinical decision-making. The limitations of this study include the small sample size of six dogs and the use of healthy subjects in a highly controlled environment (anesthetized and mechanically ventilated), which did not reflect the complexity of critically ill patients. Additionally, the non-randomized sequence of interventions introduced potential bias. However, the authors did acknowledge these limitations and attempted to mitigate bias by randomizing the ultrasound images prior to analysis.
Takeaways
External jugular vein distensibility index (EJVDI) measured by POCUS appears to be a non-invasive and promising tool for predicting fluid responsiveness in dogs. A threshold around 22.7% may help distinguish fluid responders from non-responders in anesthetized, mechanically ventilated dogs, and EJVDI correlates well with other established dynamic variables. While these results are encouraging, they should be interpreted as proof-of-concept rather than definitive clinical guidance. Broader validation in more diverse canine populations, including critically ill and spontaneously breathing patients, is needed before EJVDI can be reliably applied into routine veterinary critical care.
