Alterations in Local Peri-Infarct Blood Gases in Stroke Patients Undergoing Thrombectomy

Ischemic stroke is a prevalent, devastating disease with high morbidity and mortality. Despite extensive research using animal models, significant gaps remain in understanding the pathological processes in human stroke. We previously developed a tissue bank to analyze the blood immediately proximal and distal to an intracranial thrombus in patients undergoing mechanical thrombectomy (ClinicalTrials.gov identifier, NCT03153683). Our goal for the present project was to evaluate the blood gas changes and acid/base balance during stroke and determine how vascular collateralization affects these changes.

We analyzed the blood samples and computed tomography angiography collateral scores from the first 62 patients in the BACTRAC (Blood and Clot Thrombectomy Registry and Collaboration) registry. The bicarbonate, partial pressure of oxygen, and partial pressure of carbon dioxide (pCO₂) values of the intracranial (distal) and systemic (proximal) arterial blood relative to the occlusive thrombus were analyzed. Analysis of the group differences in systemic and intracranial blood gas values was also performed.

The partial pressure of oxygen, pCO₂, and bicarbonate levels were all significantly higher in the systemic blood than in the intracranial blood (P < 0.001 for all) at thrombectomy. Collateralization did not significantly affect the distal blood gas values. Compared with the female patients, the male patients had had higher systemic pCO₂ values (39.8 vs. 36.6 mm Hg; P = 0.0065) and lower systemic and intracranial pH values (7.351 vs. 7.392; P = 0.0047).

The arterial blood gases differed immediately proximal and distal to thrombi in large vessel occlusive stroke. Although vascular collateralization did not appear to affect the blood gas changes, some blood gas values differed between men and women. The changes in bicarbonate and pCO₂ suggested a compensatory acid-base process occurring at the time of infarction.