The Effect of Anesthesia on Cerebral Oxygenation

One-lung ventilation (OLV) is a commonly used technique in thoracic surgeries. In thoracic surgeries performed with OLV, there may be changes in cerebral tissue oxygenation depending on both patient position and anesthetic technique. The effect of cerebral hypoxia on postoperative cognitive functions is controversially. Despite the ISPOCD1 study in which concluded that there were no relationship between the cerebral hypoxy and postoperative cognitive dysfunction (POCD) regional cerebral oxygen saturation decrements during surgery are listed among the POCD When OLV begins, alveolar hypoxia and arteriovenous shunt of deoxygenated blood occur in the dependant lung. And then, hypoxic pulmonary vasoconstriction (HPV) in non-ventilated lung segments occurs with increased mechanical stress. This event lead to significant physiological changes in cardiac output and pulmonary and systemic pressures In OLV, the propofol-based total intravenous anesthesia (TIVA) and inhalation general anesthesia techniques are frequently used. Recent studies have shown that unlike inhalational anesthetics, propofol does not suppress HPV, indeed increases it (Inhalational anesthetic agents reduce cardiac output more than oxygen consumption, causing a decrease in mixed venous partial pressure of oxygen, which stimulates hypoxic pulmonary vasoconstriction . Studies have shown significant reductions in cerebral oxygen saturation in thoracic surgery as a result of severe oxidative stress due to prolonged OLV and hypoxemia due to decreased functional residual capacity of the ventilated lung in the lateral decubitus position Cerebral oximetry is a method used to monitor the cerebral oxygen distribution-consumption balance and regional oxygen saturation (rSO2) in a limited area of the frontal cortex by noninvasively and continuously combining arterial and venous oxygen saturation signals of near-infrared spectroscopy (NIRS), which is a technique developed in the 1970s. Thanks to this method, perioperative physiological conditions, optimal tissue oxygenation and end-organ functions can be interpreted The aim of this prospective study was to compare the potential effects of TIVA and inhalation general anesthesia techniques on cerebral tissue oxygenation and postoperative cognitive functions in patients receiving one-lung ventilation in thoracic surgery

Inclusion criteria

• Patients in American Society of Anesthesiology (ASA) classification I and II
• Patients who would undergo thoracic surgery with one-lung ventilation (OLV)
• thoracic surgeries with one-lung ventilation (OLV) that will take at least 45 minutes

Exclusion criteria

• Patients in ASA classification III and higher
• Emergency surgery
• Patients with known allergy to drugs used in the study
• Patients in New York Heart Association classification III-IV
• severe metabolic, renal, hepatic, central nervous system diseases, alcohol or drug addiction
• multiple trauma, coagulapathy, cerebral disease, dementia, hearing impairment and imperception
• severe obesity (a body mass index (BMI) of ≥ 35)
• patients with a peripheral oxygen saturation below 90 during one lung ventilation