Although blood transfusion is a representative treatment for acute anemia due to blood loss during surgery, it is also a powerful risk factor for postoperative cognitive dysfunction.

'Restrictive transfusion', which transfusions minimal red blood cells, is not only useful for conserving limited blood resources, but also does not worsen prognosis or mortality after surgery. Research has also been reported that severe restrictive transfusion has improved prognosis and mortality.

However, anemia is also one of the risk factors for postoperative complications, including neurocognitive impairment, it is still controversial how much anemia should be allowed in elderly people who are sensitive to ischemia or heart disease.

The purpose of this study is to determine whether the restrictive transfusion policy reduces the frequency of postoperative cognitive dysfunction than the liberal transfusion policy in patients aged 65 years or older who undergo lumbar interbody fusion.

Restrictive transfusion strategy (which initiates transfusion when hemoglobin level is less than 8 g / dL during perioperative period) // liberal transfusion strategy (which initiates transfusion when hemoglobin level is less than 10 g / dL during perioperative period)

The Aim of this study was to compare the frequency of postoperative cognitive dysfunction diagnosed 7 days after surgery between two groups.

K-MOCA (Korean-Montreal Cognitive Assessment) is used to evaluate cognitive dysfunction. In addition, plasma inflammatory markers (CRP, IL-6) and GFAP reflecting brain damage were measured before and after surgery to determine whether brain injury caused by systemic inflammatory response is associated with cognitive dysfunction

Inclusion Criteria:

• Patients 65 years of age or older who receive more than two levels of lumbar interbody fusion

Exclusion Criteria:

• If patients have anemia (Hb is less than 13 g / dL for men and less than 12 g / dL for women)
• Those who cannot read the agreement (illiteracy, foreigner, etc.)
• Have a history of taking medication for mental illness
• Communication disorders due to neurological diseases (dementia, stroke, seizures, etc.)
• Less than 23 points on K-MoCA test
• When fluid loading and volulyte are difficult due to kidney disease
• Limited blood transfusion due to heart disease
• Refusal of blood transfusions (religious reasons, etc.)
• patients who have received a blood transfusion within 6 weeks prior to surgery
• If continuous observation is impossible after surgery
• Emergency surgery