Effect of Volume Depletion and Intravascular Volume Overload on Ultrasonographically Derived Caudal Vena Cava Parameters in Healthy Sedated Cats.

OBJECTIVE

To sonographically assess caudal vena cava (CVC) and focused cardiac ultrasound (FCU) parameters for volume depletion (VD) and intravascular volume overload (IVVO) in healthy cats.

DESIGN

Prospective, randomized, blinded, crossover study.

SETTING

Experimental.

ANIMALS: Twenty-nine healthy research-purposed cats.

INTERVENTIONS: The VD group received 2 mg/kg furosemide IV every 30-60 min over 6 h, followed by 10 mL/kg isotonic crystalloid or tetrastarch given over 10 min. The IVVO group did not receive furosemide and was administered 30 mL/kg isotonic crystalloid over 10 min. Ultrasonographic images of the CVC (subxiphoid view) and heart (right parasternal short-axis view) were recorded and subjectively evaluated by an operator in real time from both groups at baseline (T0), after furosemide/6 h (T1), and after fluids (T2). CVC inspiratory (CVCinsp) and expiratory (CVCexp) diameters, CVC collapsibility index (CVCCI), left atrium-to-aorta ratio (LA:Ao), and left ventricular internal diameter in systole (LVIDs) and diastole (LVIDd) were measured and subjectively graded post hoc by two blinded raters (different to the operator) for CVC parameters; one blinded rater evaluated FCU parameters.

MEASUREMENTS AND MAIN

RESULTS

In the VD group, CVCinsp (p = 0.004), CVCexp (p = 0.008), LVIDs (p < 0.001), and LVIDd (p < 0.001) were smaller after administration of furosemide. In the IVVO group, CVCinsp (p = 0.02), CVCexp (p = 0.04), LVIDs (p < 0.001), and LVIDd (p = 0.001) were larger after fluid administration. The LA:Ao ratio was not different in any group at any time. Intrarater and interrater reliability were moderate to poor. Subjective CVC and FCU assessments were consistent with objective measurements.

CONCLUSIONS

Experimentally induced VD and volume overload result in sonographically detectable changes in the CVCinsp and CVCexp diameters and LVIDs and LVIDd of cats, suggesting the assessment of these parameters may have value in the clinical setting.