Acute ischemic stroke is a common disease, which has the characteristics of high disability rate, high mortality rate and high recurrence rate. With the development of nerve interventional technology and interventional materials, the recanalization rate of endovascular treatment has been continuously improved. Of the 90 cases in this study, 88 cases achieved different degrees of vascular recanalization, and the recanalization rate reached 97.7%, among which the good recanalization rate (mTICI 2b-3 grade) reached 85.5%.
There are many factors affecting the clinical prognosis of endovascular therapy for acute ischemic stroke. For example, age, time factors, collateral compensatory ability, baseline NIHSS score, blood pressure, blood sugar, thrombus load, anesthesia methods, etc.[9]. According to Table 1, there was no statistical difference in baseline data such as age, onset time and baseline NIHSS score between the two groups (all P > 0.05). In addition, there are clear and unified requirements for blood pressure, blood sugar and other indicators in the research and implementation process. The elimination of these common influencing factors makes the comparative study of the two anesthesia methods true and reliable.
The influence of anesthesia methods on EVT in AIS has been debated endlessly. Due to the need of preoperative preparation, the puncture time in GA group was delayed, and the prolongation of puncture time could lead to the decrease of good vascular recanalization rate (mTICI 2b-3 grade) and the prolongation of recanalization time, resulting in poor clinical neurological prognosis. Therefore, some doctors prefer local anesthesia or conscious sedation when performing EVT in AIS[10–12]. Retrospective analysis showed that the neurological function improvement effect of intravascular treatment under GA for 90 days was worse than that of CS group[13]. In a Mate analysis published by Adeel Ilyas et al. in 2018, 9 studies were included, and 1379 cases were collected, including 761 cases in GA group and 618 cases in CS group. The good prognosis of all patients at 90 days was evaluated (mRS ≤ 2 points). The final results showed that there was no significant difference in clinical prognosis between patients in the two groups[14]. Another meta analysis showed that the clinical prognosis of patients in GA group was better than that of CS group[15]. The above research results are all retrospective research results. Because there are some defects in retrospective study, retrospective analysis will lead to patient selection bias: age, ischemia severity, etc. There is no clear and unified standard to define general anesthesia and anesthesia depth, and the information provided for intraoperative anesthesia management, including blood pressure management, respiratory management and blood sugar control, is even more limited. The results showed that there was no significant difference in 90-day good prognosis (mRS ≤ 2) between patients in the two groups (P > 0.05). NIHSS scores and MRS scores were improved in different degrees at 30 and 90 days after operation, but there was no significant difference in average improvement rate between the two groups (P > 0.05). This study showed that the puncture time in patients in the CS group was faster than that in GA group. The results showed that the operation in in patients in the CS group started faster than that in GA group, the puncture time was shortened, and the corresponding vascular recanalization time, vascular recanalization rate and clinical prognosis should be better than that in GA group. However, the results showed that there was no difference in clinical neurological prognosis, mTICI grade of vascular recanalization and vascular recanalization time between patients in the two groups. The reason is that although CS shortens the puncture time of femoral artery, it may prolong the operation time when intravascular operation is performed under CS. There will be irritability symptoms caused by catheter and guide wire stimulating intracranial blood vessels, and it will increase respiratory frequency and make the head shake obviously, which will have a significant impact on DSA acquisition and fluoroscopy, which will not only prolong the operation time of patients, increase the fluoroscopy radiation dose of patients, but also prolong the opening time of blood vessels, and fail to obtain satisfactory results. Although there was no difference in prognosis between patients in the two groups, there were advantages and disadvantages between the two anesthesia methods. The advantages of CS were as follows: (1) The neurological function of patients can be evaluated at any stage of intravascular treatment; (2) It can shorten the puncture time of femoral artery and shorten the start-up time of operation; (3) Reduce iatrogenic hemodynamic fluctuations; (4) It can prevent some patients from entering ICU because of postoperative anesthesia recovery difficulties, and reduce related complications, such as lung infection[16, 17]. Advantages of GA: (1) Using anesthesia can avoid artifacts caused by exercise, and the doctor's operation process becomes smooth; (2) It can improve the patient's tolerance and ensure the smooth operation; (3) It can reduce the risk of respiratory obstruction, respiratory depression, carbon dioxide accumulation and reflux aspiration in the absence of airway protection, and keep the respiratory tract unobstructed; (4) It can keep patients quiet and reduce vascular injury induced by guide wire[18–19].
This study also pay attention to the interaction among anesthesia methods, blood pressure and neurological function improvement. Previous studies have shown that blood pressure fluctuation caused by GA is greater. Among several variables of blood pressure, MAP is the strongest predictor. For every 10% decrease of mean arterial pressure, adverse prognosis will increase by about 1.6 times. Intraoperative MAP decrease of > 40% or lower than (78 ± 8mmHg) is an independent predictor of neurological dysfunction[20–22]. It may be that the decrease of cerebral blood flow caused by hypotension aggravates cerebral ischemia and hypoxic injury[23]. According to the data in Table 4 and Fig. 3, the mean arterial pressure of both groups decreased after anesthesia, and the mean arterial pressure of general anesthesia group decreased more within 1 hour after anesthesia, which was different from that of conscious sedation group. It may be that induced hypotension may occur when using anesthesia inducers such as propofol and fentanyl[24]. The difference of MAP between the two groups did not lead to the difference of neurological prognosis. It may be that the MAP in GA group quickly returned to the ideal level after short-term fluctuation under the action of vasoactive drugs, and the lowest MAP in GA group also reached (83.50 ± 11.64), and the MAP in both groups remained at a relatively higher level during operation, thus avoiding cerebral tissue perfusion deficiency caused by sharp and long-term decrease of blood pressure. Therefore, the sharp changes of blood pressure during anesthesia should be closely monitored.
Arterial dissection is a common complication after mechanical embolectomy for AIS. According to literature reports, the incidence of arterial dissection after EVT treatment in AIS is 0.9%-3.9%[25, 26]. During intravascular treatment, the injury of intima caused by guide wire and catheter is considered as the main cause of carotid dissection[27]. In this study, the incidence of carotid artery dissection was significantly different between patients in the two groups (Table 2). Because of the shallow anesthesia depth of conscious sedation group, the patient's tolerance to pain and vascular stimulation during operation was poor, which leads to irritability and easy movement during operation, which can cause intimal injury of blood vessels and lead to arterial dissection during operation.
At present, in China, people over 60 years old are called old people, and those over 80 years old are called the old man[28]. Elderly patients with many basic diseases, poor reserve function of the body have high surgical risks during surgery, and any stimulation during anesthesia can cause excessive stress response of the body, thus causing metabolic changes and organ failure[29]. The incidence of pulmonary infection in elderly patients after GA is high and severe. The main reasons are as follows: 1. The elderly patients have poor respiratory muscle function, slow cough and expectoration reflex, and poor respiratory self-protection ability. 2. Elderly patients have many basic diseases, and most of them suffer from chronic lung diseases. Poor compliance of the lungs leads to poor systolic and diastolic functions, which easily leads to the accumulation of sputum in the lungs[30]. 3. General anesthetics and muscle relaxants can inhibit cough reflex. Because of the slow metabolism of anesthetics in elderly patients, patients can't wake up in time after operation, which is one of the causes of lung infection[31]. 4. Patients under GA are easy to accumulate sputum in throat and lung infection during endotracheal intubation and ventilator-assisted breathing[32]. Consistent with the literature, after stratified statistics of patients of different ages, the pulmonary infection rate and mortality rate of elderly patients in GA group were significantly higher than those in CS group, and the hospitalization time in ICU in GA group was significantly longer than that in CS group. Therefore, for elderly patients, surgery should be performed under CS as much as possible.