The Effect of Hypotensive Anesthesia on Cognitive Functions in Orthognatic Surgery

The purpose of this study is to evaluate the effects of maintaining adequate cerebral oxygen saturation on patients undergoing orthognathic surgery. Orthognathic surgery is performed to repair anomalies in the maxillofacial skeleton for both aesthetic and functional purposes. During these procedures, controlled hypotensive anesthesia is commonly used to reduce bleeding, improve surgical field visibility, and shorten operation time.

In controlled hypotensive anesthesia, mean arterial blood pressure is deliberately reduced to approximately 55-60 mmHg. While this technique offers surgical advantages, it may potentially reduce cerebral blood flow and oxygen saturation, which could affect cognitive function.

This study will investigate the relationship between cerebral oxygen saturation levels maintained during orthognathic surgery and postoperative neuropsychological outcomes. Patients will undergo cognitive assessments before and after surgery while cerebral oxygen saturation is continuously monitored during the procedure. Our findings will help establish safety parameters for hypotensive anesthesia in orthognathic surgery and potentially contribute to improved anesthesia management protocols that better preserve cognitive function.

Orthognathic surgery is a surgical procedure performed to repair anomalies in the maxillofacial skeleton. It can be performed for maxillofacial aesthetics as well as for functional purposes. Since orthognathic surgery is performed in a field where vascular structures are dense, complications such as intraoperative bleeding are likely to occur.

Le Fort I osteotomy and bilateral sagittal split ramus osteotomy (BSSRO) are frequently used treatment methods for dentofacial deformities. Significant bleeding may occur especially during Le Fort I osteotomy. Therefore, controlled hypotensive anesthesia is frequently used during maxillofacial surgery procedures to reduce bleeding, increase the visibility of the surgical field, and prevent blood loss.

During controlled hypotensive anesthesia, mean arterial blood pressure (MAP) is reduced to around 55-60 mmHg. This technique makes the operation more comfortable for both the surgical team and the anesthesia team. Vasoactive and anesthetic agents such as direct-acting vasodilators, autonomic ganglion blockers, beta-adrenergic receptor blockers, and calcium channel blockers are used to provide hypotensive anesthesia.

However, prolonged hypotension may lead to organ damage due to hypoperfusion. Uncontrolled prolongation of systemic hypotension may cause cerebral ischemia, neuronal death, and permanent brain damage by causing a decrease in cerebral blood flow. Cerebral circulation has a complex and unpredictable autoregulatory mechanism. Therefore, it is difficult to maintain the balance between hypotension and cerebral perfusion.

Changes in cerebral blood flow and cerebral tissue perfusion may cause cognitive changes because they affect the nutrition of neural tissues. The aim of this study is to evaluate the effects of controlled hypotensive anesthesia applied in orthognathic surgery on intraoperative cerebral blood flow-cerebral oxygen saturation and cognitive functions of patients and to determine the degree of these effects.

As part of the study, cognitive function tests will be performed on the patient population before and after surgery, and cerebral oxygen saturation will be continuously monitored during surgery. The results may help determine the safety limits of hypotensive anesthesia applied during orthognathic surgery and potentially develop cerebral protection strategies.

The results of this research are expected to contribute to the development of new approaches to improve anesthesia management in patients undergoing orthognathic surgery. Additionally, by testing the hypothesis that maintaining cerebral oxygen saturation may improve cognitive outcomes, it can contribute to increasing patient safety in maxillofacial surgical practices.

Eligibility Criteria:
Inclusion Criteria:

Patients undergoing Orthognathic surgery under general anesthesia ASA grade ≤ grade III; Patients can communicate normally, can cooperate and complete cognitive function test; Patients volunteered and signed informed consent.

Exclusion Criteria:

BMI \< 18 or \> 27 kg / m2; Previous history of dementia, psychosis or other central nervous system diseases or mental diseases, such as cerebral infarction, stroke, Parkinson's disease, etc; Patients taking sedatives or antidepressants; Alcoholics or drug addicts; Patients with cognitive impairment before operation (MMSE score \< 23); Patients with peripheral vascular diseases and contraindication of arterial puncture and catheterization; Patients unable to carry out long-term follow-up or poor compliance.