Normobaric Hyperoxia for Intracerebral Hemorrhage A Randomized Clinical Trial

Intracerebral hemorrhage (ICH) is an intractable and life-threatening stroke subtype that imposes a significant impact on people's well-being and quality of life. ICH-induced mechanical compression to the surrounding brain tissue is a major injury that increases intracranial pressure (ICP). High ICP can decrease cerebral blood flow (CBF) and influence cerebral metabolism in perihematoma and even the whole brain. Decreased aerobic metabolism and perfusion in perihematomal injury can exacerbate edema and enlarge hematoma. Moreover, secondary injury in the perihematoma, such as ischemia, oxidative stress, inflammatory response, and protease release, involves more than the initial tissue damage induced directly by the hematoma. Theoretically, low CBF and abnormal metabolism in ICH patients expose the brain tissue to the ischemic-hypoxic condition, which is similar to that in the ischemic penumbra in stroke. Therefore, the key to treating ICH is to find an approach that can rescue the perihematoma. Improving hypoxia in perihematoma seems to be a promising therapeutic candidate paradigm for ICH due to its pivotal role in the pathogenesis of perihematomas.

Normobaric hyperoxia (NBO), supplied by a face mask (such as oxygen storage face mask) with atmosphere pressure (1ATA = 101.325 kPa, 100% O2), has been considered a safe, convenient, and promising therapy for correcting various diseases and thus garnered great attention in recent years. The effectiveness of NBO on ischemic stroke (IS) has been fully identified. A plethora of studies show that NBO is capable of increasing the partial pressure of oxygen (PO2), elevating the blood flow and volume, protecting the blood-brain barrier (BBB), improving oxidative metabolism, reducing free radical damage, and even relieving inflammatory response in the penumbra. Rapid amelioration of hypoxia in brain tissue can restore brain dysfunction and improve clinical prognoses. Likewise, NBO is also regarded as a promising method for treating ICH. An animal study found that NBO for a period of 6 h per day for 3 consecutive days imposed a remarkable neuroprotective effect in rat ICH, improved neurological function, reduced brain edema, downregulated HIF-1α and VEGF expression and showed a reduction in apoptotic cells in the perihematoma. Although many clinical trials have shown the effectiveness and safety of NBO in treating ischemic stroke, there is currently a lack of trials focusing on using NBO to treat ICH. Accordingly, we conducted a proof-of-concept, single-center, randomized controlled trial to evaluate the safety and efficacy of NBO in treating ICH patients so as to explore an innovative adjuvant therapy for ICH.