Brief Report
Inferior vena cava assessment in the bedside diagnosis of acute heart failure

https://doi.org/10.1016/j.ajem.2011.04.008Get rights and content

Abstract

Objectives

The objective of this study was to determine the test characteristics of the caval index and caval-aortic ratio in predicting the diagnosis of acute heart failure in patients with undifferentiated dyspnea in the emergency department (ED).

Methods

This prospective observational study was performed at an urban ED that enrolled patients, 50 years or older, with acute dyspnea. A sonographic caval index was calculated as the percentage decrease in the inferior vena cava (IVC) diameter during respiration. A caval-aortic ratio was defined by the maximum IVC diameter divided by the aortic diameter. The sensitivity, specificity, and likelihood ratios of these measurements associated with heart failure were estimated.

Results

Eighty-nine patients were enrolled in the study with a mean age of 68 years. A caval index of less than 33% had 80% sensitivity (95% confidence interval [CI], 63%-91%) and 81% specificity (95% CI, 68%-90%) in diagnosing acute heart failure, whereas an index of less than 15% had a 37% sensitivity (95% CI, 22%-55%) and 96% specificity (95% CI, 86%-99%). The sensitivity of a caval-aortic ratio of more than 1.2 was 33% (95% CI, 18%-52%) and the specificity was 96% (95% CI, 86%-99%). Positive likelihood ratios were 10 for a caval index of less than 15%, 4.3 for an index of less than 33%, and 8.3 for a caval-aortic ratio of more than 1.2.

Conclusion

Bedside assessments of the caval index or caval-aortic ratio may be useful clinical adjuncts in establishing the diagnosis of acute heart failure in patients with undifferentiated dyspnea.

Introduction

Emergency physicians in the United States annually care for more than 650 000 patient visits for acute heart failure (AHF) [1]. To provide optimal care to these patients, rapid differentiation of AHF from other causes of dyspnea is desired. Recent data have indicated that bedside assessment of the inferior vena cava (IVC) could be a rapid, noninvasive means for clinicians to determine a patient's volume status, and thus aid in differentiating AHF from other common etiologies of dyspnea [2].

The objective of this study was to determine the test characteristics of IVC ultrasonography for diagnosing AHF in the evaluation of patients with acute dyspnea. Specifically, this study evaluated the test characteristics of the caval index, defined by the percentage change in the IVC diameter through a respiratory cycle, and the caval-aortic ratio, defined by the ratio of the static IVC and aortic diameters.

Section snippets

Study design and setting

This was a prospective observational study of adult ED patients presenting with the chief complaint of acute dyspnea. Informed written consent was obtained from patients, and the study was approved by the institutional review board of the participating hospital.

This study was conducted at an urban, academic ED with an annual patient volume of 94 000 patients. Patients were enrolled between September 1, 2008, and April 30, 2009, as a convenience sample. Inclusion criteria were adults 50 years

Results

A total of 92 patients were enrolled, of whom 89 were included in the final analysis. Three patients (3%) were excluded because of inability to visualize the IVC. Investigators reported image acquisition to require 5 minutes or less in 78% of the patients. The mean age of the cohort was 68 years. There were 52 men (58%) and 37 women (42%); 80 were black (90%), 6 white (7%), and 3 Hispanic (3%). The admission rate for the cohort was 80%, and the survival to discharge was 99%. A comparison of

Discussion

Dyspnea is a common condition for which clinicians seek a noninvasive assessment of a patient's volume status. This study aimed to determine whether measurements of IVC respirophasic change can contribute to this assessment. This study also analyzed whether static measurements of the maximum IVC diameter compared with the aortic diameter have diagnostic value in this assessment.

The data reveal that in patients presenting with acute dyspnea, smaller caval indices increase the likelihood that a

Limitations

This study was performed at a single center, and enrollment occurred primarily during daytime hours as a convenience sample. Unintended factors in enrolling this sample may have influenced the results. The study also limited enrollment to patients older than 50 years so as to include a higher proportion of patients with heart failure. By chance, no patient with cardiac tamponade or right ventricular failure was enrolled in this study. A low caval index should be applied with caution if there is

Conclusions

We propose that bedside assessment of the caval index or caval-aortic ratio has potential for complementing the clinical assessment of patients with acute dyspnea. Further studies may confirm how clinicians may incorporate such measurements into clinical decision making in the ED.

References (15)

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Prior presentations: Preliminary data presented at the Society for Academic Emergency Medicine Annual Meeting, New Orleans, LA, 2009.

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