The goal of this clinical trial is to investigate the effect of perioperative administration of vitamin C on postoperative pulmonary complications, with the aim of providing a safe and effective medication regimen for the prevention and treatment of postoperative pulmonary complications in patients undergoing surgery for craniocerebral tumors. The main questions it aims to answer are:

1. To determine whether vitamin C can reduce pulmonary complications after surgery for intracranial tumors.
2. Does intraoperative vitamin C improve the prognosis of surgical patients

Researchers will compare vitamin C to a placebo (saline) to see if vitamin C is effective for postoperative lung complications in patients undergoing surgery for cranial tumors.

1. Participants will be intravenously pumped with vitamin C for two hours after induction of anesthesia.
2. Participants will have intraoperative plasma sampling and recording of ventilator parameters, monitor parameters and perioperative data.
3. Participants will be followed up until discharge from the hospital to record symptoms and adverse events, and will be called at six months to check on their prognosis.

Neurosurgery has a high incidence of postoperative pulmonary complications, increasing patient costs and affecting patient prognosis. Neurosurgery often requires hyperventilation to reduce intracranial pressure, so methods to reduce postoperative pulmonary complications such as small tidal volumes cannot be used routinely, and larger tidal volumes often result in injury to pulmonary endothelial cells, which leads to increased permeability of the pulmonary microvasculature, resulting in mechanically ventilated lung injury. Of course surgical injuries and mechanical ventilation can also cause oxidative stress injury to the lungs. Vitamin C is a common antioxidant drug and cofactor in the synthesis of many substances in the body, and many studies have shown that vitamin C prevents the increase in endothelial barrier permeability due to many causes. During the COVID-19 epidemic, vitamin C is seen as an important adjunct in preventing and ameliorating symptoms of COVID-19 patients. not only that, but vitamin C also assisted in postoperative analgesia and promote incision healing, so investigators would like to observe that by giving vitamin C during the surgery is able to prevent the occurrence of postoperative pulmonary complications or improve the prognosis of participants.

Inclusion Criteria:

1. Patients who need craniotomy treatment due to intracranial tumors;
2. age 18-75 years old;
3. American Society of Anesthesiologists classification: 1~3;
4. Patients and their families agree to participate in the study and sign the informed consent form.

Exclusion Criteria:

1. Patients with severe pulmonary infection or respiratory failure prior to surgery;
2. Patients with previous history of neurological or psychiatric diseases;
3. Patients with cardiac, hepatic and renal insufficiency;
4. patients who are receiving parenteral nutrition;
5. pregnant patients;
6. Patients ruled out by medication instructions;
7. Patients who require emergency surgery;
8. patients with combination of other malignant tumors;
9. patients who have participated in other clinical studies of drugs within 3 months.

Individual Participant Data(IPD) will be available when this trial is finished and the article have been published