From the Research
Minimum Carotid Stump Pressure for Safe Ligation
The minimum carotid stump pressure for safe ligation is a critical factor in determining the safety of carotid artery ligation. According to the studies, the following points can be noted:
- A systolic stump pressure in excess of 70 mm Hg indicates adequacy of collateral hemispheric blood flow to allow safe ligation of the carotid artery 1.
- Pressures of 55 mm Hg or less constitute an unacceptable vulnerability to stroke, and intermediate pressures of 55 to 68 mm Hg constitute a genuine hazard 1.
- A low carotid stump pressure is defined as systolic pressure <50 mm Hg, and patients with low stump pressure are at higher risk for perioperative stroke 2.
- Stump pressure is a marker for decreased cerebrovascular reserve, and along with symptomatic status, it identifies those at highest risk for periprocedural stroke with carotid endarterectomy 2.
Factors Influencing Carotid Stump Pressure
Several factors can influence carotid stump pressure, including:
- Clinical presentation, including history of prior stroke 3.
- Presence of contralateral disease, including complete carotid occlusion 3.
- Age, with octogenarians being more likely to have lower stump pressure 2.
- Systemic blood pressure, with maintenance of appropriate systemic blood pressure being essential for safe ligation 1.
Reliability of Carotid Stump Pressure
The reliability of carotid stump pressure in predicting the need for a shunt or the safety of carotid artery ligation is debated:
- Carotid artery stump pressure has greater predictive value for shunt requirement when it is greater than 50 mmHg or less than 25 mmHg 3.
- Monitoring the neurological status of the patient in the awake state is still the most reliable method of determining shunt requirement 3.
- The absolute value of the stump pressure may not be a useful index of a good collateral circulation, and the ratio of the initial mean stump pressure to the pre-occlusion mean arterial pressure may be a more useful index 4.