6: Does Ultrasonography Measurement of Inferior Vena Cava and Inferior Vena Cava/Aorta Ratio Correlate With Fluid Therapy In Clinically Dehydrated Children With Gastroenteritis?

Article Outline

• Background
• Study Objectives
• Methods
• Results
• Conclusions
• Copyright

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Background 

Dehydration is commonly encountered in the ED and is a leading cause of morbidity and mortality among children. Accurate assessment is important. The standard is to use clinical signs and symptoms; however, these methods have a low sensitivity and specificity. Previous studies have looked at using ultrasonography to image inferior vena cava (IVC) diameter and collapsibility to help determine fluid status in children. IVC size in children varies with age/size (need to compare to BSA), and there are no reference values.

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Study Objectives 

To look at IVC and IVC/aorta ratio as a novel way to evaluate body fluid status by determining the association between IVC and IVC/aorta ratio and the amount of fluid given over time during fluid resuscitation of clinically dehydrated children with gastroenteritis in the ED. The size of the aorta will not change significantly with fluid therapy. Serial measurements of the IVC and IVC/aorta ratio (ratio goal approx. 1) will correlate with fluid resuscitation therapy.

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Methods 

Prospective, observational study, convenience sample of clinically dehydrated patients <18 years old presenting to the ED with vomiting, diarrhea, poor oral intake, and decreased urine output. ED physician determines severity of dehydration based on clinical judgment. Longitudinal anteroposterior diameter measurements of the IVC minimal (min) and maximal (max), distal to the confluence with hepatic veins, and proximal transverse measurements of the aorta were performed. There was no compression of the abdomen and no graded compression to move the bowel. The IVC min and max and aorta measurements were performed at baseline and after one 20 cc/kg fluid bolus. Descriptive statistics were computed for IVC, aorta, and IVC/aorta ratio. The Wilcoxon Signed Rank test was used to determine whether there was a statistically significant difference between IVC, aorta and IVC/aorta ratio before and after 20cc/kg bolus.

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Results 

Enrolled 20 patients ages 9 months to 16 years. There was a significant difference in IVC (mm) before hydration and after a bolus of 20cc/kg was given (IVC min difference = 0.350, p<0.0078; IVC max 0.195, p<0.0068, n=7). There was no significant difference in aorta (mm) before hydration and after a bolus of 20cc/kg was given (aorta difference = −0.040, p<0.3125, n=7). The IVC/aorta ratio before hydration and after a bolus of 20cc/kg (IVC/aorta ratio at baseline mean 0.72, median 0.75; IVC/aorta ratio after hydration mean 1.12, median 1.01; median difference = 0.27, p<0.1563, mean difference 0.40, n=11).

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Conclusions 

There is a significant difference in IVC diameter before and fluid hydration in clinically dehydrated children. Conversely, aortic diameter is not significantly affected by intravascular volume changes. Therefore, comparing IVC diameter with aorta diameter can be a promising method of estimating body water status without the necessity of looking for reference values for the IVC and aorta for each age group.