Ultrasonographical Assessment of Caudal Vena Cava Size through Different Views in Healthy Calves: A Pilot Study

Abstract

Ultrasonographic measurements of the caudal vena cava (CVC) and aorta (Ao) are known as reliable tools to assess intravascular volume status in humans. The aim of this study was to evaluate the feasibility of obtaining ultrasonographical measurements of CVC and Ao in two different views, assess intra- and interobserver variability, and study the effect of sex, age, body weight, and breed on measurements in healthy calves. The diameter and area of CVC and Ao were measured by a single investigator in two anatomic sites (subxiphoid and paralumbar window) in 48 calves aged less than 60 days and then repeated 2.5 months after the first assessment. For intra- and interobserver variability assessment, CVC and Ao measurements were repeated by three observers on five randomly selected calves. CVC and Ao measurements were easily obtained in PV and more difficult to obtain in SV. CVC and Ao area in PV showed high repeatability and reproducibility. A positive correlation was highlighted between age and CVC and Ao measurements in both sites. In conclusion, CVC size assessment by point of care ultrasound can be easily performed at a paralumbar site in calves under 4 months of age and could be used to assess intravascular volume status.

Keywords: calf; caudal vena cava; intravascular volume status; point-of-care ultrasound.

Figure 1

Subxiphoid site: (a) probe placement site and (b) ultrasonographic view of caudal vena cava (CVC) crossing the diaphragm (Yellow arrow). The blue star shows the position of the probe marker. CR: cranial; CAUD: caudal.

Figure 2

Paralumbar site: (a) probe placement site and (b) transversal and (c) longitudinal ultrasonographic views of caudal vena cava (CVC) and aorta (Ao). The blue star shows the position of the probe marker in transversal and longitudinal view. CR: cranial; CAUD: caudal.

Figure 3

Evolution over time of the percentage (%) of the successful SV cineloop acquisition in calves in the first part of the protocol. Each visit is shown as the completion date (day/month/year). Score 1: No cineloop was recorded because of the impossibility to visualize the CVC on the xyphoid site. Score 2: Cineloop was recorded but the margin of CVC was unclear which made obtaining measurements of the CVC impossible. Score 3: Cineloop was recorded with well-defined margins of the CVC that allowed precise measurements.

Figure 4

Box and whisker plots of the CVC measurements at the subxiphoid site when the CVC crossed the diaphragm. The CVC_min is CVC minimal diameter and the CVC_max is CVC maximal diameter measured.

Figure 5

Correlation coefficients (R²) between calves’ age and weight and caudal vena cava (CVC) and aorta (Ao) measurements at paralumbar views (PV). ***: p < 0.001, **: p < 0.01, *: p < 0.05. CVCdLong and AodLong are respectively CVC and Ao diameter at longitudinal PV, and CVCdLong and AodLong are the CVC and Ao diameter index in longitudinal PV. AodTrans is Ao diameter in transversal PV, CVCaTrans and AoaTrans are respectively CVC and Ao area at transversal PV, and CVCaTrans and AoaTrans are the CVC and Ao area index in transversal PV.