Velocity changes in femoral vessel ultrasound with Doppler in Porcine hemorrhagic shock

Abstract

Physician-directed point-of-care ultrasound (PoCUS) is routinely used to identify the etiology of shock and guide therapy in the ICU. We performed a preclinical study to determine what changes are manifested in the femoral vessels during hemorrhagic shock on Duplex imaging and to generate a femoral vessel sonographic profile over the time course of shock. A preclinical study in swine was performed using a convenience sample of animals that were being used in a Trauma Surgery training lab. The animals developed progressive unregulated hemorrhage during the lab. Six anesthetized swine underwent Duplex studies of the femoral vessels prior to any hemorrhage and at two time points after the start of hemorrhage. N/A. Femoral vessel imaging was performed using a portable ultrasound (Sonosite and Clarius). Femoral arterial peak systolic velocity decreased in all animals with hemorrhage, from a mean (SD) of 77 (27) cm/s pre-hemorrhage to 42 (17) and 32 (16) cm/s at the two post-hemorrhage time points. There were also changes to the arterial waveform morphology. Mean venous velocities also decreased with hemorrhage (20, 11, 7cm/s). Animals with severe hemorrhage had a cessation of venous flow during positive pressure ventilation. In this preclinical study, both femoral peak systolic velocity and venous velocity decreased with hemorrhage. Femoral vessels represent an easily accessible target for non-invasive hemodynamic monitoring. Changes in femoral vessel Duplex waveforms and velocities should be studied both in a larger sample of animals with controlled hemorrhage and in human trauma patients to determine whether changes appear in early hemorrhage, before the onset of clinically evident hemorrhagic shock.