recruitment difficulties, high postoperative drop-out rate

Cerebral blood flow is tightly regulated to ensure constant cerebral perfusion independently from systemic blood pressure fluctuations. This mechanism is termed cerebrovascular autoregulation and preserves adequate cerebral perfusion in a range between 50 and 150 mmHg of cerebral perfusion pressure. Upper and lower autoregulatory limits may vary individually. Beyond the autoregulatory range the protective autoregulatory response is lost, facilitating cerebral ischemia or hyperemia.

The cerebrovascular response may be altered during general anesthesia, through direct effects of anesthetic agents on the vascular tone, changes of arterial partial pressure of carbon dioxide or the administration of vasoactive substances. The association of perioperative impairment of cerebral autoregulation and postoperative cognitive function has been discussed controversially.

• continuous monitoring of cerebrovascular autoregulation using the correlation method
• based on near-infrared spectroscopy and invasive blood pressure measurement an index (COx) will be calculated
• autoregulation monitoring from anesthesia induction until emergence from anesthesia
• assessment of preoperative cognitive function during preanesthesia evaluation or on the day before surgery
• assessment of postoperative cognitive function between day 3 and 14 following surgery
• evaluation of subjective cognitive complaints or attention deficits 3 months after surgery

Inclusion Criteria:

• elective major non-cardiac/non-vascular surgery
• anticipated surgical duration >120 minutes
• age >= 60 years
• indication for invasive blood pressure measurement
• native German speaker

Exclusion Criteria:

• history of cerebrovascular disease
• preexisting cognitive impairment
• history or presence of neurological disease

screening of patients scheduled for preanesthesia evaluation prior to major non-cardiac/non-vascular surgery