Peripheral Vascular Surgery Society

Jonathan A. Levison, MD, Glenn R. Faust, MD, Vivienne J. Halpern, MD, Anthony Theodoris, BS, Roxana G. Kline, MD, and Jon R. Cohen, MD

Long Island Jewish Medical Center, New Hyde Park, NY.

Purpose: Protamine sulfate (PS) neutralization of heparin (HEP) given during carotid endarterectomy (CEA) has been previously associated with an increased postoperative stroke rate. Dosing regimens of PS have varied in previous studies. The accuracy of PS dosing and its effect on postoperative complications was analyzed.

Methods: The medical records of all patients undergoing elective CEAs from 1/93-6/96 in our institution were reviewed. Data obtained included age, sex, dosing regimens of HEP and PS, methods of cerebral monitoring/protection, type of endarterectomy closure, as well as the presence of postoperative hematoma and stroke. A hematoma was defined as either an event requiring return to the operating room or when repeatedly identified in the medical record. The accuracy of dosing PS was determined utilizing a formula calculating the logarithmic exponential decay of HEP, determining the residual HEP at the time of PS dosing. An ideal PS dose was then calculated and compared to the dose given. Statistical analyses was performed using a fisherâs exact test as well as the Studentâs t-test.

Results: 407 CEAs were performed in 365 patients. There were 10/407 (2.5%) postoperative strokes (STROKE) and 11/407 (2.7%) hematomas, 3 of which required reoperation. 365/407 (89.6%) CEAs received PS and 42/407 (10.4%) did not. All 10 patients with STROKE received PS. Of the patients with postoperative hematomas, 7 patients received PS (7/365, 1.9%) and 4 patients did not (4/42, 9.5%) (p=0.02, odds ratio 5.129). Analysis of the accuracy of PS dosing revealed that those patients with a STROKE received 143.5% ± 35.6 of their expected dose, as compared to 152.5% ± 41.3 in those patients without a stroke (NO STROKE). Those patients with hematomas receiving PS were given a dose 162.1% ± 61.4 in excess of expected, as compared to 151% ± 40.8 in those patients without hematomas receiving PS. In the STROKE group, 8/10 (80%) patients were shunted vs. 230/397 (58%) in the NO STROKE group and 4/10 (40%) of the endarterectomies were closed primarily in the STROKE group vs. 79/397 (19.9%) in the NO STROKE group. There were no significant differences found between any of the above groups.

Conclusions: These results indicate that (1) the administration of PS significantly reduces the incidence of postoperative hematoma; (2) there appears to be an association between the administration of PS and STROKE; (3) the inaccuracy in dosing PS appears to be based on a decision to dose PS to the total HEP given, rather than the residual HEP on board at the time of neutralization. The effect of PS overdosing is unclear, but may play a role in STROKE. This study reinforces the need for a prospective randomized analysis utilizing accurate dosing of PS to better assess its risks in carotid surgery