The Effect of Epidural/General and Cervical Plexus Block Anesthesia on Activated Clotting Time in Patients Undergoing Vascular Surgery

Abstract

The effect of anesthetic induction and surgical incision on activated clotting time (ACT) was determined in patients undergoing vascular surgery. Patients undergoing carotid endarterectomy (CAE) (n = 50) and abdominal aortic aneurysm repair (MA) (n = 45) were studied. Patients in the CAE group had cervical plexus block anesthesia, whereas patients in the AAA group had a combination of epidural and general anesthesia. The ACT was measured 1) before induction of anesthesia, 2) 5 min after induction, 3) 5 min after incision, 4) 5 min after heparinization, and 5) at the onset of skin closure. Heparin was reversed with protamine only if the ACT after revascularization was >200s. Reversal was considered adequate if the ACT was <200 s and the surgeon felt that hemostasis was adequate. The ACT decreased by 12.26 ± 1.23 (mean ± SE) (P = 0.006) in the CAE group and by 12.47 ± 1.01 (P = 0.002) in the AAA group with induction of anesthesia. There was a further decrease of 5.06 ± 0.62 (P = 0.26) in the CAE group and 5.17 ± 0.83 (P = 0.22) in the AAA group with incision. There was a significant difference in ACT in both groups from postinduction and postincision to skin closure (higher at skin closure). No patient in either group required additional protamine or clotting factors post-operatively, or return to the operating room for excessive bleeding. This study demonstrates that anesthetic induction with cervical block or epidural/general anesthesia decreases ACT. The time of the initial ACT measurement is not important in patients undergoing vascular surgery, because ACT does not need to be returned to baseline to assure adequate hemostasis. (Anesth Analg 1993;76:701–4)