188: CAROTID ARTERY DIAMETER DECREASES FOLLOWING SAGITTAL, NON-IMPACT ROTATIONAL HEAD INJURY

Abstract

Introduction: Modification of cerebral perfusion pressure and cerebral blood flow are crucial components of the therapies designed to reduce secondary damage after traumatic brain injury (TBI). Previously we documented a robust decrease in cerebral blood flow (CBF) after rapid sagittal head rotation in our well-validated animal model of diffuse TBI. Mechanisms for this immediate (<10 min) reduction in CBF have not been explored. Methods: Four-week old (toddler) female piglets (n=4) underwent rapid (<20msec) sagittal head rotation without impact, previously shown to produce diffuse TBI with reductions in CBF. Ultrasound images of the bilateral carotid arteries were recorded at baseline (pre-injury), as well as 15, 30, 45, and 60 minutes after injury. Diameter (D) and waveform velocities (V) were used to calculate blood flow (Q) through the carotid arteries using the equation Q = (0.25)∏D2V, which was normalized to the pre-injury baseline values to obtain a relative change after injury. One sample T-tests were used to compare normalized diameter and flow to their baseline values (normalized baseline values = 1). Results: The carotid artery diameters decreased significantly at all time points after injury, to 85% ± 4% of their pre-injury values. At 15-min post-TBI, carotid artery flow decreased significantly to 75% ± 16% of pre-injury levels, while decreases at later time points to 79% ± 32% of baseline did not reach significance with our small group size. Conclusions: These data suggest that reductions in CBF after rapid sagittal head rotation may be related to reductions in carotid artery diameter and flow, and that carotid artery flow may be a useful adjunctive technique to estimate CBF in some settings to assist in the management of patients with traumatic brain injury. Funding provided by NIH NSR01039679.