Advances in neurosurgical anesthesia in 2020

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Advances in neurosurgical anesthesia in 2020

Advances in neurosurgical anesthesia in 2020.  Neurosurgical anesthesia is an important branch of the field of brain science. Neurosurgical anesthesia should continue to explore the best ways to improve the prognosis of patients’ neurological function.

This article will summarize the latest literature in the field of neurosurgical anesthesia published in 2020 from three aspects: brain tumor, cerebrovascular disease and traumatic brain injury (TBI), hoping to provide help for clinical practice.

1.   Progress in anesthesia for brain tumor surgery

1.1　 Perioperative management of patients with brain tumors

For patients with brain tumors near the functional area of ​​the brain, intraoperative wake-up anesthesia can more comprehensively monitor the brain function of the surgical area during the operation. Arzoine et al. conducted a survey at the European Low-Grade Gliomas Network (ELGGN) center to explore the anesthesia management methods for awakening anesthesia during surgery for low-grade gliomas. Researchers sent questionnaires to 28 centers, and finally received responses from 20 centers. The results show that the proportion of centers using SAS (Sleep‑Awake‑Sleep) and MAC (Monitored Anesthesia Care) programs in ELGGN centers is the same. However, Picart et al. questioned the timeliness of the conclusions of the study and believed that hypnosis-aided awake surgery (HAS) has been widely used.

Previous studies have observed that HAS can reduce the psychological trauma associated with awake surgery and reduce the incidence of intraoperative pain and discomfort, but related studies generally have non-random review bias. Therefore, Pesce et al. further studied the therapeutic effects of standard wake-up surgery and HAS on high-grade gliomas. The researchers reviewed the clinical data of the two groups of surgical cohorts, and compared and analyzed the HAS surgical plan and the standard intraoperative wake-up anesthesia plan, showing that the short-term nervous system function, surgical resection range, and perioperative complications of the two plans are similar . However, HAS surgery takes longer and requires professionals to participate in intraoperative anesthesia management.

Intraoperative awakening of anesthesia requires the active cooperation of the patient. Post-traumatic stress disorder (PTSD) is a relative contraindication for this type of surgery. Patients with PTSD usually exhibit severe anxiety and have a stronger response to the trauma of awakening anesthesia during surgery. In 2020, two teams shared the successful anesthesia management experience of intraoperative wake-up anesthesia for PTSD patients. Preoperative neurocognitive evaluation and consultation of patients, describing their PTSD, and determining the incentives; during the operation, patients are encouraged to actively communicate, create a safe and controllable surgical environment, and successfully complete the intraoperative wake-up anesthesia without complications. The study emphasizes the importance of a multidisciplinary team, preoperative determination of PTSD incentives, and a safe and controllable intraoperative environment for awakening anesthesia during this type of operation.

Fatigue is a common symptom of cancer patients, and previous studies have reported that fatigue has a negative impact on the health-related quality of life of glioma patients. Schei et al. conducted a prospective study that included 112 adult patients and assessed their fatigue and Karnofsky (Karnofsky Performance Status, KPS) functional status scores before and 1 month after surgery. The results of the study showed that high preoperative fatigue was related to women and low KPS scores, and postoperative high fatigue was related to complications, low KPS scores, and low-grade histopathology. Research data shows that patients with low-grade gliomas mostly exhibit low fatigue before surgery and high fatigue after surgery; while patients with high-grade gliomas mostly exhibit high fatigue before surgery and low fatigue after surgery. The study showed that preoperative and postoperative fatigue in patients with diffuse glioma is a common symptom and is affected by perioperative management.

Tracheal intubation is a routine method to ensure airway safety in neurosurgical anesthesia. However, during intubation and extubation, it may cause severe hemodynamic fluctuations and even lead to adverse outcomes. In daily anesthesia management, the laryngeal mask has been widely used, but its use in neurosurgical craniotomy is still limited. To this end, Zhang et al. studied the feasibility and effectiveness of laryngeal mask and tracheal intubation in the right supine-tentorial tumor resection. The researchers used a randomized controlled trial to randomly divide 80 patients into a laryngeal mask group and a tracheal intubation group, and compare the data of patients’ hemodynamics, mechanical ventilation, anesthesia dose, complications, and quality of anesthesia recovery. The results of the study showed that patients in the laryngeal mask group had lower MAP and heart rate, and the dose of sufentanil was reduced by 24%. Therefore, if there are no contraindications, the study suggests that the laryngeal mask may replace the tracheal intubation during the resection of the right supine-tentorial tumor.

1.2 　 Perioperative drug application in patients with brain tumors

Studies on anesthetized patients have shown that phenylephrine can reduce regional cerebral oxygen saturation (rSO2) compared with ephedrine. Recently, Koch et al. conducted a randomized controlled clinical trial to further quantify the effects of phenylephrine and ephedrine on cerebral blood flow and cerebral oxygen metabolism rate in patients with brain tumors. Researchers enrolled 24 patients with brain tumors, randomly treated with ephedrine or phenylephrine, and performed positron emission tomography (PET) scans on the periphery of the tumor and the normal area on the contralateral side to measure cerebral blood flow. And cerebral oxygen metabolism rate. The results of the study showed that compared with phenylephrine, ephedrine had similar effects on the cerebral oxygen metabolism rate of the tumor periphery and the contralateral normal area, but significantly increased the contralateral cerebral blood flow and rSO2.

Brain edema induced by brain tumors often causes severe nerve damage. Steroids can be used to treat cerebral edema, but there are serious adverse reactions, and there is a lack of steroid treatment guidelines for children. Malbari et al. investigated the use of steroids in children with brain tumors in order to develop a standardized treatment plan. Researchers used an anonymous and voluntary method to investigate pediatricians caring for newly diagnosed brain tumor patients, and asked them to respond to the details of the clinical protocol of the four types of steroids, such as the start time, formula, and dosage of steroid treatment. Research data shows that facing different scenarios, there is a statistically significant difference in the proportion of physicians using steroids. 98.7% of physicians use steroids to treat vasogenic edema, and 72.4% of physicians use steroids to treat obstructive hydrocephalus. The relief of edema and neurological dysfunction can significantly affect the doctor’s use of steroids. The study found that dexamethasone is recommended for the treatment of vasogenic edema and obstructive hydrocephalus, but further research is needed to complete the steroid treatment guidelines for pediatric patients.

1.3 　Influencing factors on the postoperative outcome of patients with brain tumors

With the continuous growth of the elderly population in Western society, there are more and more patients with primary brain tumors over the age of 65. Nia et al. evaluated and compared the safety, effectiveness, and results of craniotomy for brain tumors in patients over 65 and under 65. The researchers reviewed the cases of supratentorial and subtentorial craniotomy in neurosurgery from 2008 to 2016 from the ACS‑NSQIP database, stratified at the age of 65, and observed mild and severe complications during the 30-day follow-up. Disease, reoperation, length of hospital stay and case fatality rate. The results of the study show that elderly patients, metabolic syndrome, surgery more than 5 hours, ASA grade III, preoperative steroid use, etc. are important predictors of complications. The study provided a comprehensive analysis of perioperative risk factors and predictors of adverse prognosis in elderly patients with supratentorial and subtentorial craniotomy for tumors, and determined that increasing age is an independent risk factor for minor and major adverse events and prolonged hospital stay.

Previous studies have shown that anesthesia has potential damage to neurodevelopment, learning and cognitive abilities. The US Food and Drug Administration has also issued a warning that young children should avoid repeated exposure to anesthesia. Medulloblastoma is the most common malignant brain tumor in children and requires anesthesia, surgery, radiation therapy and neuroimaging during the treatment process. Jacola et al. studied the effects of anesthesia exposure during treatment of pediatric medulloblastoma on neurocognitive results 3 years after tumor diagnosis. The researchers reviewed the medical records of 111 patients treated at St. Jude Children’s Research Hospital and extracted anesthesia and nerves from them. Cognitive test data. The results of the study showed that with the increase of the anesthesia exposure time, the children’s intelligence, attention, working memory, processing speed and reading ability decreased significantly. Therefore, the authors suggest that the anesthesia exposure time during the treatment of pediatric medulloblastoma should be minimized.

Since the anesthetics used in cancer surgery may affect tumor cells and immune response, Grau et al. studied the effects of inhalation anesthesia and propofol total intravenous anesthesia on the recurrence-free and overall survival rate of patients with glioblastoma. The researchers reviewed 158 patients who underwent enhanced glioblastoma resection under general anesthesia and received standard adjuvant therapy. The results of the study showed that the choice of anesthesia method had no effect on the survival rate of glioblastoma patients.

2.  Progress in anesthesia for cerebrovascular disease surgery

2.1 　 Hemorrhagic stroke anesthesia management

Aneurysmal subarachnoid hemorrhage (aneurysmal subarachnoid hemorrhage, aSAH) accounts for about 5% of strokes and has a very high mortality and disability rate. The prognosis of patients usually depends on the degree of initial bleeding and the secondary brain damage caused by the bleeding. Among them, secondary brain injury involves multiple mechanisms such as blood-brain barrier damage, brain edema, neuroinflammation, and cerebral vasospasm. Choosing the best anesthetic drugs and anesthesia management methods and minimizing these unfavorable factors are the tasks and challenges faced by anesthesiologists.

Cerebral vasospasm is one of the important causes of delayed cerebral ischemia (DCI) after aSAH. It is closely related to the poor prognosis of patients, but its prevention and treatment methods have been lacking new breakthroughs. A recent retrospective study by Athiraman et al. suggested that inhaled anesthetics may help improve cerebral vasospasm after aSAH. This cohort study included 390 patients undergoing aneurysm surgery under general anesthesia after aSAH to evaluate the potential effects of inhaled anesthesia on the prognosis of postoperative cerebral vasospasm, DCI, and neurological function. The results suggest that simple inhalation anesthesia is significantly related to the reduction in the incidence of cerebral vasospasm and DCI, but has no significant effect on the modified Rankin Score (mRS) of patients at discharge.

Previous animal experiments suggested that its molecular mechanism may be that inhaled anesthetics induce the production of nitric oxide synthase and vascular endothelial growth factor, and inhibit endothelin-mediated microvascular contraction. This study provides new ideas for the prevention of cerebral vasospasm after aSAH. However, the study is a single-center retrospective study with a small sample size and lack of standard anesthesia management. Prospective studies are needed to further verify that inhaled anesthetics fight cerebral vasospasm Its effectiveness and its impact on the long-term prognosis of patients. At the same time, it is also necessary to explore the effective concentration and treatment time window of inhalation anesthetics under the premise of good nerve monitoring.

Ensuring proper blood volume and cerebral perfusion is one of the strategies to prevent cerebral vasospasm after aSAH. The current volume management and hemodynamic assessment mainly rely on clinical experience and lack objectivity and consistency. Goal-directed therapy (GDT) uses non-invasive cardiac output monitoring to accurately guide the use of fluids and vasoactive drugs in accordance with preset algorithms to achieve more scientific circulation management. Chui et al. conducted a randomized controlled study in which GDT was used to optimize volume and hemodynamic management in the early stage of interventional therapy for aSAH, which preliminarily confirmed the feasibility and effectiveness of this method.

The study included 40 patients who underwent endovascular treatment within 5 days after aneurysm rupture and bleeding. They were randomly assigned to the GDT group (21 cases) and the standard treatment group (19 cases). Both groups were monitored by NICOM, and the GDT group was based on non-invasive The results of cardiac output monitoring were subjected to precise fluid therapy and drug treatment. The standard treatment group concealed the results of non-invasive cardiac output monitoring.

The study found that 60% of patients were dehydrated before the start of endovascular treatment (EVT); compared with standard therapy, GDT can effectively reduce the duration of intraoperative hypovolemia (37.6 min, P=0.006) and hypocardia Exponential duration (30.7 min, P=0.035); however, there was no statistically significant difference in the incidence of cerebral vasospasm, stroke and other serious complications between the two groups of patients at 90 days. The study suggests that non-invasive cardiac output monitoring can effectively identify blood volume insufficiency in patients with aSAH. Early application of GDT management can optimize the circulatory management of patients with aSAH. However, a larger sample size study is needed to evaluate the effects of GDT on patients with cerebral vasospasm and remoteness. The impact of the prognosis.

Dexmedetomidine (sexmedetomidine, Dex) is a selective α2 adrenergic receptor agonist, which has been widely used in anesthesia, analgesia and ICU sedation. Animal experiments have confirmed that Dex can regulate the delayed brain injury of SAH patients through a variety of mechanisms. On the one hand, Dex can improve cerebral perfusion by regulating vasoconstriction and relaxation, thereby maintaining intracranial homeostasis; on the other hand, Dex can protect vascular endothelium, fight microthrombosis, repair the blood-brain barrier, prevent cerebral vasospasm, and inhibit cortical spread. Sexual depolarization and other aspects have a certain effect. Dex has a strong animal experimental basis for the brain protection of SAH patients, but there is insufficient clinical evidence. In the future, more clinical studies are needed to confirm its potential advantages.

2.2 　 Anesthesia management for ischemic stroke

There is no uniform standard for blood pressure management during acute ischemic stroke (AIS) EVT. To this end, Rasmussen et al. conducted a secondary analysis of the results of 3 randomized controlled studies to explore the effect of intraoperative blood pressure on the prognosis of patients’ neurological function. The study finally screened 365 patients receiving EVT, including 182 patients under general anesthesia and 183 patients under sedation. The mRS at 90 days was used as the main outcome index to evaluate the neurological outcome.

Studies have found that both hypotension and hypertension during EVT are associated with poor prognosis, with MAP<70 mmHg (1 mmHg=0.133 kPa) for more than 10 minutes, or >90 mmHg More than 45 minutes indicates a poor neurological outcome; the study also pointed out that using MAP as a guide is more sensitive and reliable than SBP. Valent et al. retrospectively analyzed 371 patients undergoing EVT surgery, of which 42% were under general anesthesia and 58% were under local anesthesia.

The researchers found that no matter which anesthesia method is selected, the decrease in MAP during EVT is more than 10% of the baseline and the duration is greater than 10 minutes, indicating a poor neurological outcome. Researchers believe that the choice of anesthesia may not be the fundamental factor in determining the prognosis of patients, and blood pressure management is more critical to the clinical outcome of patients.

The best method of anesthesia during EVT is still inconclusive. Cappellari et al. conducted a large retrospective cohort study to compare the effects of general anesthesia, conscious sedation, and local anesthesia on the neurological function and long-term prognosis of patients. The study analyzed the data of 4 429 cases based on prospective collection. After adjusting for age, gender, National Institute of Health Stroke Scale (NIHSS) score, anticoagulant and antiplatelet drug use and other related confounding factors, the results showed that compared with conscious sedation and local anesthesia, The long-term prognosis of patients in the general anesthesia group is poor, with a higher mortality rate, but the incidence of postoperative cerebral hemorrhage is lower. There is no statistically significant difference in the recanalization rate between the three groups. The study also found that the neurological outcome and long-term outcome of the local anesthesia group The long-term prognosis seemed to be the best among the 3 groups.

In theory, compared with local anesthesia, conscious sedation can achieve a better analgesic effect, relieve patients’ anxiety while retaining their ability to cooperate, but there is still a lack of corresponding clinical evidence. To this end, Benvegnù et al. carried out a multi-center prospective cohort study. The study included 1 034 patients, including 762 in the conscious sedation group and 272 in the local anesthesia group. After matching the propensity score, the results showed that the conscious sedation group was The neurological outcome and recanalization rate were significantly better than those in the local anesthesia group. This result also has an important hint for related research on anesthesia methods during EVT, that is, when comparing the effects of general anesthesia and non-general anesthesia on the clinical outcome of patients, local anesthesia and conscious sedation should not be confused.

Since 2014, a number of prospective, randomized, and controlled trials on the choice of anesthesia and the neurological outcome of AIS patients with EVT have been successively registered in Clinicaltrials, including SIESTA (NCT02126085), GOLIATH (NCT02317237), ANSTROKE (NCT01872884), CANVAS (NCT02677415) , GASS (NCT02822144), AMETIS (NCT03229148), the results of the first three trials have been published. The scheme design, main outcome indicators, methods of anesthesia and the connotation of anesthesia management of these three trials were different, but they all showed different results from the previous cohort study.

The results of the meta-analysis of 3 randomized controlled trials showed that the 90-day mRS score of patients with anterior circulation AIS under EVT general anesthesia was 2.8 points (95%CI 2.5~3.1), and the conscious sedation group was 3.2 points (95%CI 3.0~3.5). It is suggested that general anesthesia may be beneficial to the neurological outcome of patients after EVT (odds ratio 1.58, 95% CI 1.09-2.29). However, the gap between the two groups of general anesthesia and conscious sedation is weak, and there is strong evidence that the results of Meta analysis are often inconsistent with the results of subsequent large-sample, prospective, randomized, and controlled trials.

Therefore, the causal relationship between the choice of anesthesia method and the clinical prognosis of EVT remains controversial so far. Further multi-center prospective, randomized, and controlled trial data are needed to confirm that the two anesthesia methods of general anesthesia and conscious sedation are effective in the clinical outcome of AIS patients. influences. An article recently published by Wiles put forward new thinking on the choice of anesthesia methods and blood pressure management strategies during EVT surgery.

The study believes that blood pressure management seems to be more important than the choice of anesthesia. Regardless of the anesthesia method, the patient’s neurological outcome is similar when the SBP is maintained at 140-160 mmHg. Wiles also proposed that the anesthesia management of AIS patients should follow the principle of individualization, and how to transform population data into individualized blood pressure targets is a major challenge in the future. In addition, the fine management of the anesthesia process is far more important than the choice of anesthesia method.

Body temperature management is a problem that AIS patients cannot ignore. Current studies believe that maintaining a normal body temperature during the perioperative period is more beneficial than interventional hypothermia, but for patients with pre-operative fever, active fever reduction is beneficial to improve patient outcomes. However, it is not clear whether different temperature management strategies are needed before and after the EVT is activated. To this end, Diprose et al. carried out an observational study that included a total of 432 patients who received EVT. The study found that the increase in body temperature before and after EVT was associated with poor neurological prognosis. Every 1 ℃ increase in body temperature caused death of the patient. The rate increased by about 0.6 times. The study once again confirmed the impact of perioperative temperature management on the clinical outcome of EVT patients, and emphasized the importance of early intervention.

2.3 　 Carotid endarterectomy (carotid endarterectomy, CEA) anesthesia management

CEA is an important means to treat symptomatic carotid artery stenosis. According to reports, the incidence of perioperative stroke in CEA patients is 2.3% to 7.4%. Therefore, timely detection of brain tissue hypoperfusion during surgery and effective intervention are very important to reduce postoperative neurological complications. Evoked potential monitoring is a more mature method of cerebral ischemia monitoring in CEA, but it has high technical requirements and motor evoked potential monitoring restricts the use of muscle relaxants.

In recent years, near-infrared spectroscopy rSO2 monitoring has attracted more and more attention. rSO2 can non-invasively and continuously monitor the oxygenation of brain tissue during surgery, effectively identify hypoperfusion during temporary blockade, and assist in guiding the placement of shunt tubes. The early warning threshold of rSO2 for ischemia monitoring in CEA has been controversial, and the range of research reports is 11.7%~25.0%. In response to this problem, Yu et al. compared the diagnosis of cerebral ischemia/hypoxia by rSO2 combined with evoked potential monitoring during the temporary carotid occlusion period.

A total of 203 patients with CEA were included in the study, 23 of which showed positive changes in evoked potential during the blocking period. The results of the study further verified that the decrease of rSO2 has a strong correlation with evoked potential monitoring of cerebral ischemia (R2=0.15, P=0.02 ), and pointed out that a 16% drop in rSO2 as the cutoff value for ischemia has the best diagnostic value, and the positive predictive value and negative predictive value are 76% and 99%, respectively. Nevertheless, rSO2 monitoring still has a certain false positive rate (8.9%), and other monitoring methods are needed in clinical work to improve its diagnostic accuracy.

Studies have confirmed that severe hemodynamic fluctuations (severe hypotension and bradycardia) in CEA are closely related to the incidence of postoperative stroke, but existing studies have paid insufficient attention to occult strokes without obvious clinical symptoms after surgery; in addition; For high-risk groups, the current cycle management strategy is still slightly broader. In response to this problem, Rots et al. explored the correlation between intraoperative blood pressure fluctuations in CEA patients and occult strokes suggested by diffusion weighted imaging (DWI).

This case-control study included a total of 55 patients, of which 8 had new strokes diagnosed by DWI; the results of the study showed that the baseline blood pressure of these 8 patients was significantly higher than that of the non-stroke group [(186±31) mmHg and (158 ±27) mmHg, P=0.011)]; and, although the incidence of absolute hypotension (blood pressure <80 mmHg) was lower in the two groups, the decrease in intraoperative MAP was significantly greater in the new stroke group [( −37±29) mmHg and (−14±26) mmHg, P=0.024)].

The study suggested that the occult stroke after CEA should not be ignored. Poor control of preoperative hypertension and a large drop in intraoperative blood pressure are risk factors for occult stroke after CEA. Therefore, patients with hypertension before CEA operation should be more stringent blood pressure management. Whether such patients should continue to take antihypertensive drugs in the morning after operation is also worth re-discussing.

3 TBI surgical anesthesia progress

3.1 Perioperative management of TBI patients

Secondary ischemic/hypoxic injury often occurs after TBI. The goal of treatment for TBI patients is to maintain adequate cerebral blood flow and adequate arterial oxygen content. Studies have shown that arterial hyperoxia may be beneficial to ischemia compensation after brain injury, overcome oxygen diffusion barriers, and improve mitochondrial function. Wettervik et al. reviewed 115 patients with severe head injury treated in the neuro-intensive care unit of a Swedish hospital from 2008 to 2018, and analyzed the brain microdialysis, arterial blood gas, hemodynamics and intracranial pressure data of the patients 10 days after the injury. . The study found that maintaining oxygen partial pressure above 12 kPa may improve brain energy metabolism and intracranial pressure auto-regulation, especially in the case of limited energy substrate supply in the early stage of TBI. Near-infrared spectroscopy is a method of monitoring brain oxygenation in patients with TBI, which can guide timely intervention and reverse local brain tissue hypoxia. A systematic review by Mathieu et al. pointed out that there is a link between cerebral hypoxia detected by near-infrared spectroscopy in the acute phase of traumatic brain injury and adverse outcomes.

Low partial pressure of brain tissue oxygen (PbtO2) has been shown to be an independent predictor of adverse outcomes in brain injury. Choosing appropriate mechanical ventilation to achieve appropriate oxygenation indicators is the basis for the treatment of patients with craniocerebral injury. Robba et al. conducted a single-center retrospective cohort study of 70 patients with craniocerebral injury who underwent advanced neurological monitoring in the neuro-intensive care unit of Cambridge University Hospital from 2014 to 2018. The results showed that PbtO2 of 28 mmHg can be used as a critical value for judging cerebral hypoxia, and PaO2/FiO2 is the main determinant of cerebral hypoxia and patient death.

The purpose of TBI treatment is to provide sufficient oxygen to brain cells to avoid secondary injury caused by increased intracranial pressure or decreased cerebral perfusion pressure. Harrois et al. performed intracranial pressure monitoring on 18 TBI patients requiring mechanical ventilation, and recorded changes in postural changes and intracranial pressure changes after sputum suction. It was found that changes in body position and sputum suction can cause long-term increase in intracranial pressure and decrease in cerebral perfusion pressure.

3.2 　 Perioperative drug application in TBI patients

Intravenous anesthetics are commonly used in patients with severe head injury due to their neuroprotective properties, but the effect of these drugs on the cerebral blood flow of patients with traumatic brain injury is still unknown. Froese et al. conducted a systematic review of the literature on the effects of propofol, fentanyl, and midazolam on the cerebral blood flow of patients with moderate/severe TBI and animal models published before May 2020. The results showed that the above three drugs are effective There is no statistically significant difference in the effects of cerebral blood flow in TBI patients, and further animal experiments and clinical studies are still needed to verify in the future.

Hausburg et al. reviewed the existing evidence from animal model studies and clinical studies and found that propofol may provide brain tissue protection by regulating the function of astrocytes. These protective effects may vary with the duration of propofol use after injury. Prolonged (>48 h) high-dose (>5 mg·kg−1·h−1) use of propofol may cause a rare side effect-propofol infusion syndrome, which is mainly manifested as metabolic acidosis , Myocardial ischemia and rhabdomyolysis. TBI is an independent risk factor for propofol infusion syndrome.

Peng et al. conducted clinical studies on the sedative, analgesic, hemodynamic, anti-inflammatory and antioxidant effects of Dex and midazolam on patients with mild head injury. In this study, all patients received intravenous injection of propofol 2 mg/kg, vecuronium 0.1 mg/kg, and ketamine 4 mg/kg for induction of anesthesia. The intraoperative BIS was maintained at 45-70.

The midazolam group included 225 patients who received 49.9 μg/kg midazolam and 1 μg/kg fentanyl intravenously before induction of anesthesia, and continued intraoperative infusion of 50 μg·kg−1·h−1 mi Dazolam until the end of the operation; Dex group enrolled 231 patients, received Dex 0.999 μg/kg and fentanyl 1 μg/kg intravenous infusion before anesthesia induction, and continued intraoperative Dex infusion 1 μg·kg−1·h− 1 to the end of the operation.

The results show that midazolam provides rapid intraoperative sedation and inhibition of oxidative reactions, while Dex provides better intraoperative sedation, postoperative analgesia and better clinical recovery, and can inhibit intraoperative oxidation and inflammatory reactions.

(source:internet, reference only)

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