Ultrasonographic Assessment of Caudal Vena Cava to Aorta Ratio as a Novel Endpoint in Hemorrhagic Shock Resuscitation in Dogs

Objective- The aim of this study was to assess ultrasonography-derived caudal vena cava to aorta ratio (CVC/Ao) as a novel endpoint in the resuscitation of experimental hemorrhagic shock in dogs. Design- Experimental study. Animals- Ten adult mongrel healthy dogs. Procedures- After induction of anesthesia (control assessments), hemorrhagic shock was induced by blood withdrawal to a mean arterial pressure of 40 to 50 mmHg within 30 minutes and then maintained in a hypovolemic situation for an additional 30 minutes (second and third stages of assessments). Afterward, the dogs were randomly assigned to two groups which received 20 ml/kg lactated Ringer's solution or 5 ml/kg Hydroxyethyl starch, in four consecutive 15 minutes intervals (fourth stage of assessments). One hour after the last resuscitation step, final ultrasonographic assessments were performed. Results- Hemorrhagic shock caused a significant decrease in the CVC and Ao diameters as well as the CVC/Ao (2.14 ± 0.28 cm, 0.85 ± 0.07 cm and 0.4 ± 0.06, respectively) (p<0.05). Following the fluid resuscitation, CVC/Ao increased and returned to pre-shock values in both groups. Conclusion and clinical relevance- Findings indicated that serial ultrasonographic assessment of the CVC/Ao can be a useful endpoint in the resuscitation of dogs with hemorrhagic shock.