Research progress of NIRS cerebral oxygen saturation monitoring in clinical anesthesia-Chemical Instrument Network

Anesthesia, as one of the fundamental steps in surgical procedures, is an important step in ensuring the smooth implementation of the surgery. However, the application of anesthesia drugs can affect the blood pressure level of the body, leading to brain tissue hypoxia, and in severe cases, can cause brain tissue damage, posing a significant threat to surgical safety and patient prognosis.Brain oxygen saturation is commonly used for monitoring the hypoxic state of the brain during surgery. Its parameters can reflect the oxygen content of brain cells, providing reliable basis for clinical surgery and helping to adjust the oxygen concentration in a timely manner during surgery, thereby preventing the occurrence of brain injury.Therefore, actively monitoring the perioperative cerebral oxygen saturation of patients is an effective way to avoid intraoperative cerebral hypoxia.

NIRS脑氧饱和度监测在临床麻醉中的研究进展

Cerebral oxygen saturation (rSO2) is a common indicator reflecting the oxygen content of human brain cells, with a normal value of 58% -82%. If the rSO2 in the body is low, it can cause brain hypoxia, leading to brain damage, and in severe cases, adverse consequences such as brain death, posing a significant threat to the safety of patients' lives. Based on this, rSO2 is now considered one of the key indicators for clinical detection of patients' vital signs and has important application value in surgical and other treatment plans. With the continuous development of rSO2 monitoring technology, it has been widely used in clinical surgery. In addition to monitoring local oxygen saturation in the brain, rSO2 levels in peripheral tissues can now be measured, which has a positive evaluation effect on the microcirculation status of peripheral tissues and is conducive to accurate assessment of patients in the future. During surgical anesthesia, patients often experience significant fluctuations in vital signs and a decrease in heart rate, which can lead to inadequate tissue perfusion, resulting in cerebral hypoxia, ischemia, and changes in the internal environment. However, arterial and venous oxygen saturation concentrations can still maintain a certain degree of stability. Therefore, monitoring rSO2 is of great significance for evaluating patients' intraoperative physical status. This article provides a review of the principle of rSO2 monitoring technology and its influencing factors and application in clinical anesthesia monitoring, aiming to provide reliable reference for the clinical application and research of this indicator.

The influencing factors of rSO2 in clinical anesthesia monitoring

1. Hypotension

After general anesthesia in surgery, patients are prone to varying degrees of hypotension, which can lead to reduced tissue perfusion, decreased oxygen supply, and cerebral hypoxia. The brain tissue oxygen saturation detector was used to monitor the hypotension of patients after anesthesia. The results showed that the local muscle oxygen saturation (rSO2) of patients with hypotension after anesthesia induction decreased significantly, while rSO2 remained relatively stable, indicating that muscle tissue ischemia and hypoxia occurred earlier after anesthesia. However, through the body's self-regulation, the oxygen supply balance of the brain can still be guaranteed. Analysis suggests that neurovascular coupling (NVC) is another form of self-regulation that can directly induce hemodynamic changes through neurogenic regulation, thereby matching neuronal metabolic activity. After anesthesia, the cerebral blood flow perfusion of the patient decreases, and the blood pressure drops significantly. Under the coupling of nerve and blood vessels, the local cerebral blood flow can be matched with the cerebral oxygen metabolism rate, and even in the case of reduced oxygen supply, the stability of blood oxygen saturation can be maintained.

NIRS脑氧饱和度监测在临床麻醉中的研究进展

2. Hemoglobin

In rSO2 monitoring, changes in infrared spectra can be influenced by the oxygen content of hemoglobin, so changes in hemoglobin properties and concentrations can affect its monitoring values. When there is a change in intracranial oxygen saturation, the absorption spectrum of hemoglobin will undergo certain changes, resulting in a change in the intensity of transmitted infrared light. By comparing hemoglobin oxygen saturation with infrared light intensity and creating a standard curve, oxygen saturation can be monitored. Research has shown that patients with moderate anemia (hemoglobin 60-90g/L) have a higher postoperative rSO2 decline rate and incidence of cerebral oxygenation disorders than normal (hemoglobin>120g/L) and mild anemia (hemoglobin 90-120g/L), indicating that patients with lower hemoglobin levels are more likely to experience rSO2 decline during surgery, and the decrease in hemoglobin levels can lead to a decrease in rSO2 monitoring values. In summary, hemoglobin is an important factor affecting the monitoring results of rSO2.

NIRS脑氧饱和度监测在临床麻醉中的研究进展

3. Anesthetic drugs

Anesthetic drugs have a certain impact on the contraction and relaxation of human blood vessels, and the different types of drugs can also lead to differences in intraoperative rSO2 monitoring results. Research has found that intraoperative hemodynamics and cerebral oxygen metabolism are more stable in patients undergoing sevoflurane combined anesthesia, indicating that the latter has a smaller impact on rSO2 in patients. However, another study showed that the effect of bing po phenol combined with etomidate anesthesia on intraoperative hemodynamics was milder in patients, with higher rSO2 levels than those maintained with sevoflurane and rui fen tai ni anesthesia. From this, it can be seen that the type and combination regimen of anesthetic drugs have a significant impact on the intraoperative rSO2 level of patients, and selecting appropriate anesthetic drugs is crucial.

4. Anesthesia method

There are significant differences in the anesthetic effects produced by different anesthesia methods. For example, in general, lumbar epidural anesthesia has a faster onset time than epidural anesthesia, and it has a significant impact on patients' rSO2 levels. Research has shown that compared to subarachnoid block, general anesthesia has a greater impact on perioperative rSO2 levels in patients. Another study showed that there was no significant difference in rSO2 values among patients under different anesthesia regimens. From this, it can be seen that there is no unified consensus on the value of anesthesia methods on intraoperative rSO2 levels in clinical practice, and its conclusion needs further research to confirm.

5. Carbon dioxide pneumoperitoneum

Research has shown that using carbon dioxide pneumoperitoneum on children can cause significant changes in rSO2. Analysis suggests that carbon dioxide pneumoperitoneum can lead to the formation of high abdominal pressure, which has a certain physical compressive effect on adjacent organs and tissues, and can easily cause restricted cerebral venous return, leading to cerebral vasodilation, increased cerebral blood flow, intracranial pressure, and other conditions, thereby affecting the rSO2 level of the body. In addition, carbon dioxide pneumoperitoneum can also cause certain hypercapnia and respiratory acidosis risks, which have a significant impact on the brain oxygen metabolism of patients. Therefore, during carbon dioxide pneumoperitoneum, the patient's rSO2 shows a certain downward trend, and as the pneumoperitoneum ends, its rSO2 level can gradually recover.

6. Position

The supine and prone positions are commonly used surgical positions. When the patient is in the prone position, the head needs to be placed sideways, and the position pad should be placed slightly lower than the trunk. Excessive stretching, bending, rotation, or tilting of the head can cause compression of the vertebral artery, leading to cerebral hypoperfusion and other conditions, which in turn can cause changes in rSO2 values during surgery. When lying prone, the patient's intraocular pressure and head venous pressure will increase, both of which can cause a decrease in ocular perfusion pressure, especially in spinal surgery, where the abdomen is compressed and pressure can be transmitted to cause an increase in central venous pressure, leading to head venous congestion and affecting the body's rSO2 levels. It can be seen that body position is an important factor affecting the level of rSO2 in patients during surgery, with rSO2 decreasing in prone position compared to supine position.

Application of rSO2 in clinical anesthesia monitoring

Application of rSO2 monitoring in surgical anesthesia for elderly patients

Elderly patients generally experience a decline in tissue and organ function, accompanied by a higher probability of cerebral oxygen imbalance during the perioperative period, which can increase the risk of poor postoperative prognosis. RSO2 can reflect the oxygen content of brain tissue and also reflect the balance of oxygen supply and demand in brain tissue. Based on this, maintaining stable rSO2 in patients can effectively reduce the occurrence of poor prognosis. Research has shown that monitoring rSO2 and bispectral index (BIS) during the perioperative period can provide reliable anesthesia medication management for elderly patients with intestinal obstruction, further reducing the risk of postoperative complications such as delirium, and is of great significance for their postoperative recovery. Postoperative delirium in elderly patients is a transient organic brain syndrome, usually caused by poor surgical prognosis due to cerebral hypoperfusion and hypoxia, which can have a serious impact on the postoperative recovery of elderly patients. RSO2 monitoring plays an important role in brain protection and effective recovery of patients, thus effectively reducing the incidence of postoperative delirium in elderly patients.

2. Application of rSO2 monitoring in cranial surgery

Craniocerebral injury is a neurological disease that changes rapidly and requires timely treatment. Normally, in order to prevent sudden drops in intracranial pressure from causing brain herniation, patients with severe intracranial injury need to undergo intracranial pressure monitoring during surgical treatment. At the same time, to prevent cerebral hypoxia, clinical monitoring of the patient's perioperative rScO2 is also necessary. The application effect of rSO2 monitoring in patients with severe traumatic brain injury was explored, and the results showed that strengthening rSO2 monitoring management can help clinical grasp the balance of cerebral oxygen supply and demand and changes in cerebral blood flow in patients, and provide good guidance for adjusting anesthesia and surgical plans. In addition, after severe traumatic brain injury, patients may experience severe and sustained stress reactions, leading to excessive excitation of the sympathetic nervous system, increased heart rate and blood oxygen, increased oxygen consumption, and elevated intracranial pressure, thereby increasing the risk of poor prognosis. Therefore, actively monitoring the rSO2 levels of patients undergoing cranial surgery is an important way to improve surgical safety and reduce prognostic risks.

NIRS脑氧饱和度监测在临床麻醉中的研究进展

3. The protective effect of rSO2 in anesthesia for surgical children

Due to the incomplete development of organs and systemic functions in children, their tolerance for anesthesia and surgery is poor, and they are prone to cerebral hypoxia and other conditions during general anesthesia. The use of anesthetic drugs can also cause reactions such as hypotension and reduced tissue blood flow perfusion, which have a significant impact on the safety of pediatric surgery. Therefore, conducting rSO2 monitoring to ensure the perioperative safety of pediatric patients is of great significance in pediatric surgical plans.

4. Application of rSO2 in anesthesia for patients undergoing transcatheter aortic valve implantation surgery

Transcatheter aortic valve implantation (TAVI) is a common surgical procedure in cardiology, which involves retrograde implantation of a new aortic valve into the corresponding position through the peripheral artery. However, the surgical process may result in complications such as aortic dissection or ventricular fibrillation, posing a serious threat to the patient's life and health. Therefore, timely assessment of the patient's physical condition is particularly important. Transcatheter aortic valve implantation surgery requires high stability of anesthesia, and selecting the appropriate anesthesia method for patients is of great significance in evaluating the surgical effect. Anesthesia and implantation surgery may cause damage to the patient's central nervous system and have a significant impact on rSO2. The central nervous system is highly sensitive to hypoxia, and mild hypoxia can cause oxidative metabolic disorders in brain cells, leading to neuronal apoptosis, decreased cholinergic function, and impaired hippocampal function related to memory, ultimately resulting in neurocognitive dysfunction. Therefore, choosing an appropriate anesthesia regimen and continuous rSO2 monitoring during surgery have a positive preventive effect on cerebral hypoxia and postoperative cognitive impairment.

summary

RSO2 monitoring can effectively evaluate the cerebral oxygen supply and demand of anesthesia patients, provide reliable guidance for their clinical operations, and ensure the safety of patients' lives. It has been widely used in the clinical treatment of various diseases. During anesthesia, the patient's oxygen and blood flow perfusion can be adjusted in a timely manner based on their rSO2 parameters to reduce brain nerve damage and ensure intraoperative safety.

NIRS脑氧饱和度监测在临床麻醉中的研究进展

The Bolian Zhongke MOC series brain tissue oxygen saturation monitor can provide continuous, real-time, and non-invasive monitoring values of tissue oxygen saturation (rSO2), which can reflect specific organs (such as the brain, mesentery, kidneys, etc.) and systemic perfusion status. Research has shown that rSO2 monitoring can detect perfusion damage in the early stages that cannot be detected by conventional hemodynamic detection methods. It can timely monitor the oxygen supply and demand balance of brain and regional tissues, dynamic changes in cerebral blood flow, evaluate brain and tissue ischemia and hypoxia early, guide perioperative management, reduce the incidence of perioperative complications, sensitively reflect the oxygenation status of tissues and intervene, optimize the entire clinical treatment management, shorten hospitalization time, and improve patient prognosis.