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Blood gas and carotid pressure: factors in stroke risk
Insights
Hypocarbic or normocarbic anesthesia during carotid endarterectomy is associated with lower stroke risk. This study highlights the safety of selective shunting in reducing stroke incidence.
Area of Science:
- Neurosurgery
- Anesthesiology
- Vascular Surgery
Background:
- Carotid endarterectomy is a surgical procedure to remove plaque from carotid arteries.
- Identifying stroke risk during surgery is crucial for patient safety.
- Internal carotid back pressure and arterial blood gas levels are potential indicators of stroke risk.
Purpose of the Study:
- To evaluate the relationship between internal carotid back pressure, arterial carbon dioxide levels (PaCO2), and stroke risk during carotid endarterectomy.
- To determine if anesthetic management (hypocarbic vs. hypercarbic) impacts neurological outcomes.
Main Methods:
- 269 patients undergoing 332 carotid endarterectomies were monitored.
- Internal carotid back pressure and arterial blood gas (PaCO2) measurements were recorded.
- Patients with low back pressure (<25 Torr) received an inlying shunt.
Main Results:
- A significant inverse relationship was found between PaCO2 and internal carotid back pressure (P < 0.0002).
- The hypercarbic group (PaCO2 > 45 Torr) had a higher incidence of neurological deficits (4 cases) compared to normocarbic and hypocarbic groups (1 case each).
- The overall stroke rate was low at 2%.
Conclusions:
- Hypocarbic or normocarbic general anesthesia may be associated with a lower stroke incidence during carotid endarterectomy compared to hypercarbic anesthesia.
- Selective shunting is a safe and effective technique during carotid endarterectomy, contributing to a low stroke rate.
Abstract:
The internal carotid back pressure and arterial blood gas measurements have been employed in 269 patients undergoing 332 carotid endarterectomies in an effort to identify individuals at high risk of stroke during surgery. Patients having an internal carotid back pressure less than 25 Torr were operated using an inlying shunt. There were 159 patients having a PaCO2 greater than 45 Torr, 95 individuals with a PaCO2 between 35 to 45 Torr and 78 cases with a PaCO2 less than 35 Torr. The mean internal carotid back pressure was 63 Torr in the hypocarbic group and 45 Torr in the hypercarbic patients which represents a highly significant inverse relationship between PaCO2 and carotid back pressure (P less than 0.0002). There were four neurological deficits following surgery in the hypercarbic group and one each in the normocarbic and hypocarbic groups. These findings suggest a lower stroke incidence in patients having hypocarbic or normocarbic general anesthesia than those receiving hypercarbic general anesthesia. The low overall stroke rate of 2% indicates the safety of selective shunting during carotid endarterectomy.