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Changes in carotid artery blood flow during anterior cervical spine surgery
Matthew E Pollard1, Patricia W Little
1Department of Orthopaedic Surgery, Atlanta Medical Center, Atlanta, Georgia, USA. matthewandelizabeth@msn.com
Study Design:
Carotid artery blood flow was measured in 15 patients undergoing anterior cervical spine surgery.
Objective:
To determine the effect of intraoperative retraction on carotid artery flow dynamics.
Summary Of Background Data:
Adequate surgical exposure for anterior cervical discectomy and fusion necessitates prolonged retraction of the carotid artery. The perioperative effects of retraction on carotid blood flow have not been investigated.
Methods:
Duplex ultrasonic measurements of common carotid artery flow velocity were taken in 15 patients undergoing anterior cervical discectomy and fusion. Measurements were recorded before surgery, intraoperatively after exposure was obtained and self-retaining retractors were placed, intraoperatively at the end of the procedure just before release of retraction, after surgery in the recovery room, and on postoperative day 1. Using flow velocity data, the changes in cross-sectional area were calculated at each time interval and expressed as a percentage of change in area from baseline measurements. The parameters of patient age, preexisting atherosclerotic vascular disease, and prolonged intraoperative retraction were analyzed to determine whether they were associated with the observed changes.
Results:
Vessel cross-sectional area decreased an average of 14% with the initial placement of self-retaining retractors, and decreased further to 70% of baseline by the end of the case. Flow remained laminar at all times, and flow velocities returned to normal in the recovery room. Although these changes were more pronounced in the younger patients studied, and appeared to be only moderately attenuated by the presence of mild preexisting atherosclerotic vascular disease or prolonged vessel retraction, these observations could not be statistically confirmed because of the small number of patients in each subgroup.
Conclusions:
Intraoperative retraction during anterior cervical spine surgery alters common carotid artery flow dynamics by causing a significant reduction in vessel cross-sectional area. These changes are most pronounced in young patients. Atherosclerotic disease is a common finding in patients evaluated for anterior cervical discectomy and fusion.