Comparison of Blunt Versus Surgical Dissection for Aortic Flow Probe Placement in the Dog

Abstract

In animal research placement, of a flow probe on the aorta provides more accurate cardiac output measurements  than alternative clinical methods, such as thermodilution. However, good advice on how to place  such a probe in the laboratory setting is lacking. In twenty anesthetized dogs midline sternotomy and left  thoracotomy approaches to the ascending aorta, using surgical (forceps with scissors) or blunt finger dissection  to separate the aorta from the adjacent pulmonary artery (four groups of five dogs), were compared.  A Transonic A-probe was placed around the aorta. Hematocrit was compared before and after surgery. The  operative site was inspected for bleeding at post mortem. Two dogs died from massive pulmonary artery  hemorrhage in the surgical dissection groupings. At post mortem, bleeding around the probe had occurred  in five dogs in the surgical dissection groupings. Significant decreases in hemoglobin occurred in the sternotomy  and surgical dissection groupings (P<0.05). Thoracotomy with blunt finger dissection to mobilize  the aorta was associated with minimal operative blood loss. It was subsequently used successfully for flow  probe placement in over fifty dog experiments each lasting 8-12h.