Carbon Dioxide, Blood Pressure, and Perioperative Stroke: A Retrospective Case-Control Study

Area of Science:

• Anesthesiology
• Neurosurgery
• Critical Care Medicine

Background:

• The link between intraoperative physiological status and postoperative stroke remains unclear.
• Hypotension and abnormal carbon dioxide levels (hypo- or hypercapnia) may contribute to cerebral ischemia.

Purpose of the Study:

• To test the hypothesis that intraoperative hypotension combined with hypo- or hypercarbia increases the risk of postoperative ischemic stroke.

Main Methods:

• A retrospective, case-control study analyzed over 1.2 million surgical cases from five academic centers (2004-2015).
• Ischemic stroke cases were matched with controls (1:4).
• Area under the curve was used to quantify time and reduction below mean arterial pressure thresholds and outside end-tidal carbon dioxide thresholds.

Main Results:

• A significant association was found between stroke and both hypotension (MAP < 55 mmHg) and hypercarbia (end-tidal CO2 > 45 mmHg).
• Strongest associations were observed with MAP < 55 mmHg (aOR 1.17) and end-tidal CO2 > 45 mmHg (aOR 1.11).
• No interaction effect was detected between blood pressure and carbon dioxide levels.

Conclusions:

• Intraoperative hypotension and carbon dioxide dysregulation are independent risk factors for postoperative stroke.
• Maintaining optimal blood pressure and ventilation during surgery may mitigate stroke risk.