The investigators aimed to research the incidence of hyperlactatemia in craniotomy cases, the relationship of lactate elevation with tumor type and other factors that may be related, and whether the general anesthesia method applied (inhalation anesthesia or total ıntravenous anesthesia) affects lactate level.

Lactate level is one of the easy-to-measure parameters that are frequently used in anesthesia and intensive care clinical practice, especially to evaluate the severity of disease and the response to treatment. In patients with high lactate levels, the first considerations are hypoperfusion and sepsis. However, many causes such as trauma, seizures, ischemia, diabetic ketoacidosis, thiamine deficiency, malignancies, liver dysfunction, genetic disorders, toxins, drugs, etc. can be associated with increased lactate. Many tissues in the body can produce lactate. 25% of production is from muscle, 25% skin, 20% brain, 20% RBC and 10% bowel cells. Some malignancies, especially hematological cancers, have also been associated with increased lactate. In recent years, it has been reported that serum lactate levels are associated with the degree of glial tumor malignancy, and that lactate can even be used as a non-invasive malignancy biomarker in brain tumors. In a recent study, it was reported that the type of 'glioblastoma multiforme' among patients who underwent craniotomy with the diagnosis of intracranial brain tumor was an independent influencer factor for preoperative and postoperative hyperlactatemia. Anesthesia is one of the factors that can affect lactate levels due to its effect on systemic perfusion and the hepatic effects of anesthetic drugs. It looks like that there is no study in the literature on the effect of anesthesia technique on hyperlactatemia in patients who underwent craniotomy. Therefore the investigators aimed to research the incidence of hyperlactatemia in craniotomy cases, the relationship of lactate elevation with tumor type and other factors that may be related, and whether the general anesthesia method applied (inhalation anesthesia or total ıntravenous anesthesia) affects lactate level.

Inclusion Criteria:

• Scheduled to undergo elective craniotomy for an intracranial mass
• adult patients

Exclusion Criteria:

• emergency
• In situations that may cause hyperlactatemia (such as sepsis, hepatic or renal failure, shock state, or patients who need inotropic support)

All patients who scheduled to undergo elective craniotomy for an intracranial mass older than 18 years old