Hyperbaric oxygen in patients with ischemic stroke following cardiac surgery: a retrospective observational trial

Hyperbaric oxygenation (HBO₂) involves breathing 100% oxygen under elevated ambient pressure in a hyperbaric chamber, thereby dissolving oxygen in the plasma. This results in an increase of arterial partial pressure of oxygen (pO₂). Though well established in experimental studies, HBO₂ treatment for ischemic stroke is still under discussion.

From 2002-2014 HBO₂ (2.2 bar, 90 minutes one/day; average number per patient: 4.7) was applied in 49 consecutive patients (32 males, 17 females, mean age: 68.8 years, range 31.2 - 83.9) with acute neurological deficit following cardiac surgery (CABG 15; combined surgery 14; valve surgery 11; aneurysm repair 8; malformation 1). Patients' history including TIA or stroke and carotid artery pathology were documented. Both degree and type of neurological deficit was evaluated by a scoring system (0-4) before and after HBO₂ treatment.

Before HBO₂ therapy, the average motor deficit score was 2.45 and the average speech disorder score was 0.55, as compared with an average motor deficit of 1.12 and an average speech disorder of 0.27 afterward (α=0.0001, α=0.009). The majority of patients had an overall improvement of 2 score-points after HBO₂ therapy (n=23 patients). Probit analysis showed that for a 50% response/probability (LC50) of having an overall outcome of ≥2 scoring points, an estimate of 4.3 HBO₂ therapy sessions is necessary.

HBO2₂ therapy was associated with significant improvement in patients with acute neurological deficits due to ischemic stroke following cardiac surgery. Though this fact suggests gas embolism as the most likely cause of stroke in this collective, other underlying pathologies cannot be ruled out. Randomized studies are needed for further evaluation.