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Carotid artery stump pressure: its variability when measured serially
1Section of Vascular Surgery, Virginia Mason Clinic, Seattle, Washington.
Insights
Carotid artery stump pressure (CSP) is highly variable during surgery, impacting decisions about bypass shunts. This variability, observed in nearly 20% of patients, may explain differing opinions on shunt necessity in carotid endarterectomy.
Area of Science:
- Neurosurgery
- Vascular Surgery
- Anesthesiology
Background:
- Carotid endarterectomy is a common procedure to prevent stroke.
- Carotid artery stump pressure (CSP) is used to guide the decision for intraoperative bypass shunt placement.
- Variability in CSP may influence the reliability of this decision-making criterion.
Purpose of the Study:
- To assess the serial variability of carotid artery stump pressure (CSP) during carotid endarterectomy.
- To determine the proportion of patients with significant CSP fluctuations that could alter shunt management.
- To identify factors associated with CSP variability.
Main Methods:
- Serial measurement of CSP in 174 patients undergoing 189 carotid endarterectomies under eucarbic general anesthesia.
- Analysis of CSP variations relative to a threshold of 50 torr.
- Correlation of CSP variability with patient demographics, preoperative status, and imaging findings.
Main Results:
- Significant CSP variation occurred in 19.5% of patients (34/174), potentially affecting shunt decisions.
- In patients with initial CSP < 50 torr, 34% (26/76) later exceeded 50 torr.
- In patients with initial CSP ≥ 50 torr, 7% (8/113) later dropped below 50 torr.
- CSP variability was not linked to age, sex, intracranial disease, or contralateral stenosis.
- Preoperative status significantly influenced CSP: asymptomatic (89%), TIA (62%), prior stroke (54%).
Conclusions:
- Carotid artery stump pressure exhibits significant variability in a substantial portion of patients undergoing carotid endarterectomy.
- This variability may contribute to conflicting findings regarding the necessity of bypass shunts in this surgical population.
- Preoperative patient status is a key factor associated with CSP levels.
Abstract:
At 189 operations in 174 patients, carotid artery stump pressure (CSP) was measured serially to determine variability during carotid endarterectomy with eucarbic general anesthesia. Overall, 34 of 174 (19.5%) had significant variation in CSP which would have affected selective use of a bypass shunt based on CSP criteria. In those with CSP initially below 50 torr, 26 of 76 (34%) rose above 50 torr even, though systemic pressure was constant or declined. Eight of 113 pts (7%) with initial CSP equal to or above 50 torr subsequent had CSP below 50 torr. CSP did not vary as a function of age, sex, intracranial disease judged by biplanar arteriography, or contralateral carotid stenosis but did vary with preoperative status. Asymptomatic patients had CSP above 50 torr in a high proportion of cases, 24 of 27 (89%) unlike those with TIA, 72 of 116 (62%) or prior stroke, 17 of 31 (54%) (P = 0.003). We conclude that carotid stump pressure is variable in many patients which may account for some of the conflicting observations on the need for shunts in carotid surgery.