Reduced cerebral oxygen saturation during thoracic surgery predicts early postoperative cognitive dysfunction.

Area of Science:

• Anesthesiology
• Neurosurgery
• Thoracic Surgery

Background:

• Thoracic surgery often involves single-lung ventilation (SLV), which can lead to intraoperative hypoxia.
• Postoperative cognitive dysfunction (POCD) is a concern following major surgeries, particularly thoracic procedures.

Purpose of the Study:

• To investigate the relationship between intraoperative oxygenation levels and the incidence of cognitive dysfunction after thoracic surgery.
• To identify specific thresholds of oxygen desaturation during SLV that correlate with cognitive impairment.

Main Methods:

• Prospective study involving 76 patients undergoing thoracic surgery with expected SLV duration >45 minutes.
• Cognitive function assessed using the Mini-Mental State Exam (MMSE) preoperatively and at 3 and 24 hours postoperatively.
• Intraoperative monitoring included standard parameters and continuous absolute oximetry (S(ct)O(2)) to track oxygen levels.

Main Results:

• A significant proportion of patients (53%) experienced S(ct)O(2) below 65% during SLV.
• Twenty-nine percent of patients showed a decrease in MMSE scores (>2 points) 3 hours post-surgery, indicating early cognitive dysfunction.
• Postoperative cognitive dysfunction was positively correlated with the duration of exposure to critically low S(ct)O(2) levels (<65%, <60%, <55%).

Conclusions:

• Early cognitive dysfunction following thoracic surgery with SLV is associated with intraoperative declines in S(ct)O(2).
• The risk of cognitive dysfunction increases with the severity and duration of intraoperative hypoxia.