Background:

Sonographic measurement of the inferior vena cava (IVC) diameter is straightforward and reliably performed by noncardiologists using hand‐carried ultrasound (HCU) at patients’ bedsides. It provides a noninvasive estimate of the right atrium pressure and might be a more accurate marker for fluid overload in acute heart failure patients when compared with the traditional bedside clinical evaluation. Yet it is not known whether IVC measurements vary in relation to the timing of intravenous furosemide. This is an important consideration because the effectiveness of intravenous furosemide is known to peak rapidly, within hours of administration. We sought to determine whether there is a noticeable difference in the IVC diameter before and after intravenous furosemide administration.

Methods:

We performed an observational study in a large, public teaching hospital. Potential eligible patients were identified from a list of daily admissions to the general medicine inpatient service. We enrolled adult patients with a diagnosis of acute heart failure exacerbation who were prescribed intravenous furosemide. Exclusion criterion was a serum albumin < 3 mg/dL. Ultrasonogra‐phy of the IVC was performed by a hospitalist attending physician and a second‐year internal medicine resident who underwent a 6‐hour training program. HCU was used to capture 2‐dimensional grayscale images of the IVC through the subcostal window. Measurements were obtained at 3 times: (1) within 1 hour before furosemide, (2) between 1 and 2 hours after furosemide, and (3) between 3 and 4 hours after furosemide. We used a random‐intercept multilevel model to account for the clustering of repeated observations on each patient. The dependent variable was IVC diameter, and the independent variables were dummy variables for time 2 (yes/no) and time 3 (yes/no).

Results:

A convenience sample of 70 patients made up the primary study cohort. Most patients were obese (mean weight, 236 pounds) and 60% had left ventricular systolic dysfunction. Within 1 hour before furosemide, median IVC diameter was 2.25 cm (IQR, 1.88–2.55 cm), suggesting that most patients had elevated right atrium pressures at baseline (values > 1.8 cm suggest pressure elevation). Between 1 and 2 hours after furosemide, IVC diameter decreased by 0.20 cm (95% CI, 0.13–0.27 cm). Then 2–4 hours after furosemide, it began to return to baseline but remained significantly below it by 0.12 cm (95% CI, 0.05–0.20 cm).

Conclusions:

In adult patients with heart failure exacerbation, the IVC diameter changes measurably in relation to the timing of intravenous furosemide. Interpretations of measurements of the IVC, therefore, should incorporate the time since intravenous furosemide. Iterative assessments of IVC diameter in acute heart failure patients should be consistently scheduled in relation to intravenous furosemide.

Disclosures:

S. Tchernodrinski ‐ none; B. Lucas ‐ none; A. Athavale ‐ none; C. Candotti ‐none; B. Margeta ‐ none; A. Katz ‐ none; R. Kumapley ‐ none