UTILITY OF THE ULTRASONOGRAPHIC
MEASUREMENT OF CAUDAL VENA CAVA ON
AORTA RATIO FOR THE DIAGNOSIS AND THE
THERAPEUTIC FOLLOW-UP OF
NATURALLY-OCCURRING HYPOVOLEMIC
SHOCK IN DOGS

Julie Combet-Curt, Céline Pouzot-Nevoret, Alexandra Nectoux, Anthony

Barthélemy

► To cite this version:

Julie Combet-Curt, Céline Pouzot-Nevoret, Alexandra Nectoux, Anthony Barthélemy. UTILITY OF THE ULTRASONOGRAPHIC MEASUREMENT OF CAUDAL VENA CAVA ON AORTA RATIO FOR THE DIAGNOSIS AND THE THERAPEUTIC FOLLOW-UP OF NATURALLY-OCCURRING HYPOVOLEMIC SHOCK IN DOGS. European Veterinary Emergency and Critical Care, Jun 2020, Online, France. hal-05079177

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# UTILITY OF THE ULTRASONOGRAPHIC MEASUREMENT OF CAUDAL VENA CAVA ON AORTA RATIO FOR THE DIAGNOSIS AND THE THERAPEUTIC FOLLOW-UP OF NATURALLY-OCCURRING HYPOVOLEMIC SHOCK IN DOGS

<figure><img src="image_1.png" /></figure>

Julie COMBET-CURT,ª Céline POUZOT-NEVORET,ª Alexandra NECTOUX,ª Anthony BARTHÉLEMYª

ªIntensive care unit (SIAMU), Université de Lyon, VetAgro Sup, APCSe, Marcy l'Etoile, France

## INTRODUCTION

The ultrasonographic (US) measurement of caudal vena cava on aorta (CVC:Ao) ratio was successfully used to assess volume status in experimental models of hypovolemia in dogs¹,². This technique has been shown to be **easy, quick, and non-invasive** with acceptable inter- and intra-operator variabilities.

The aim of this study was to determine the utility of the CVC:Ao ratio to detect naturally-occurring hypovolemic shock in dogs, to evaluate evolution of the ratio after fluid resuscitation and to evaluate if CVC:Ao ratio was correlated with blood lactates and physical parameters.

## METHODS

Dogs with hypovolemic shock admitted in our ICU (SIAMU) between September 2018 and January 2020 were prospectively enrolled. Hypovolemic shock was defined as the **presence of at least 3 physical signs consistent with hypovolemia** (altered mentation, tachycardia, weak or absent femoral pulse, pale mucous membranes, capillary refill time (CRT) > 2 seconds and cold extremities).

CVC:Ao ratio was measured on the **spleno-renal view of the AFAST protocol** as previously described (Figure 1).¹

All measures were performed before and after an **intravenous crystalloid fluid bolus** of Lactate Ringer solution at 10 mL/kg.

Reference intervals for CVC:Ao ratio were previously defined at our institution with the same US protocol as follows: **0.93-1.32**.²

Comparisons of physical parameters, ultrasonographic measurements and blood lactates concentrations among dogs before and after the bolus of fluids were performed using an one-way ANOVA. A linear approach was used to evaluate relationships between CVC:Ao ratio (predictor variable), and HR, RR, body temperature and blood lactates (dependent variable).

## RESULTS

Seventeen dogs were included in the study.

**CVC:Ao ratios** were below reference intervals at admission in 16/17 dogs and significantly **increased after the fluid bolus** (0.82 and 0.92, respectively; P = 0.007; **Figure 2**). Normalization of the CVC:Ao ratio after fluid bolus was observed in 6/17 dogs.

**Blood lactates** did not significantly change between before and after bolus (4.0 and 3.9 mmol/L, respectively; P = 0.273; **Figure 2**).

**Heart and respiratory rates** significantly decreased after the bolus (132 and 106 bpm, respectively; P = 0.002; 40 and 34 bpm, respectively; P = 0.032; **Figure 2**). **Capillary refill time** significantly shortened between before and after bolus as well (P = 0.003).

No significant linear correlation was observed between the CVC:Ao ratio and physical parameters or blood lactates before and after fluid bolus.

## CONCLUSION

The US measurement of the CVC:Ao ratio appears as a valuable and promising tool for the **diagnosis and the therapeutic follow-up of naturally-occurring hypovolemic shock in dogs**. It appears to allow earlier quantitative detection of changes in **intravascular volume status** than blood lactates concentration in dogs.

<caption>**Figure 1.** Ultrasonographic protocol</caption>

(a) The dog was positioned in right lateral recumbency and the probe placed over the left kidney area-to allow visualization of the left kidney. The probe is moved dorsally and caudally to visualize CVC and Ao in sagittal views (b); the probe is then shifted 90° clockwise to allow visualization of transversal views of both vessels (c) and measurements of two perpendicular diameters are performed (d)

<figure><img src="image_2.png" /><figcaption>**Figure 2.** Comparisons of caudal vena-cava (CVC) diameter, Aorta (Ao) diameter, CVC/Ao ratio, heart rate, respiratory rate and blood lactates before and after fluid bolus</figcaption></figure>

*P* < 0.05

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