Based on the clinical observation that over half of the patients in the management of aneurysmal subarachnoid hemorrhage(aSAH) present with spontaneous hyperventilation, which is significantly associated with delayed cerebral ischemia and poor neurological outcomes, this prospective pilot study is designed to investigate the safety and efficacy of normobaric facemask oxygen for hypocapnia in aSAH.
Spontaneous hyperventilation (SH) is highly prevalent following aneurysmal subarachnoid hemorrhage (aSAH) and is significantly associated with poor neurological outcomes.The core pathophysiological mechanism involves hypocapnia induced by hyperventilation, which triggers cerebral vasoconstriction and consequently leads to a decrease in cerebral blood flow (CBF).Although this response may transiently reduce intracranial pressure, persistent cerebral vasoconstriction markedly increases the risk of delayed cerebral ischemia (DCI) and secondary brain injury. Therefore, maintaining the arterial partial pressure of carbon dioxide (PaCO2) within the physiological range of mmHg is recommended to minimize the detrimental effects of hypocapnia. Currently, there is a lack of standardized management strategies for hypocapnia resulting from SH after aSAH. Based on physiological principles, low-flow (\<5 L/min) oxygen delivery via a facemask may effectively correct hypocapnia by promoting the rebreathing of carbon dioxide within the dead space of the facemask.10 A randomized controlled trial investigating psychogenic hyperventilation syndrome provides preliminary evidence for this approach, demonstrating that low-flow (3 L/min) facemask oxygen therapy can relieve symptoms more rapidly and improve patient comfort compared to traditional breathing training.11 However, high-level evidence regarding the safety, efficacy, and impact on neurological outcomes of using low-flow facemask oxygen therapy (functioning as a rebreathing mask) as a targeted intervention for correcting hypocapnia in aSAH patients remains scarce. Consequently, this proof-of-concept prospective study aims to systematically evaluate the operational safety and clinical effectiveness of rebreathing facemask oxygen therapy for correcting hypocapnia in patients with aSAH.
Study Type
OBSERVATIONAL
Enrollment
80
Oxygen is to be delivered via a rebreathing facemask (ensuring no one-way valve is present), with a fractional inspired oxygen (FiO2) of 25-41% and an oxygen flow rate of ≤ 5 L/min. The goals are to maintain patient SpO2 \> 95%, PaCO2 between 35-42 mmHg, and, where feasible (particularly in centers with the capability for monitoring), an intracranial pressure (ICP) of \< 15 mmHg.
Using nasal cannula for oxygen inhalation or not using oxygen inhalation at all. Monitor and record the patient's SpO2, systolic blood pressure, diastolic blood pressure, PaCO2, and also monitor the intracranial pressure (ICP) at a center with monitoring capabilities.
School of Medicine Chinese University of Hong Kong-SHENZHEN
Shenzhen, Guangdong, China
modified Rankin Scale (mRS) >3
The poor neurological outcome was considered to be mRs \>3, indicating severe disability or death. The modified Rankin Scale (mRS) is a commonly used scale for measuring the degree of disability or dependence in the daily activities of people who have suffered a stroke or other causes of neurological disability. (Score Description: 0---No symptoms at all. 1---No significant disability despite symptoms; able to carry out all usual duties and activities. 2---Slight disability; unable to carry out all previous activities, but able to look after own affairs without assistance. 3---Moderate disability; requiring some help, but able to walk without assistance. 4--- Moderately severe disability; unable to walk without assistance and unable to attend to own bodily needs without assistance. 5---Severe disability; bedridden, incontinent and requiring constant nursing care and attention. 6---Dead.
Time frame: 90-day follow-up visit
Incidence of delayed cerebral injury (DCI)
The presence of new focal neurological signs or a documented decrease in the level of consciousness persisting for at least 1 hour (or a drop of at least 1 point in the total Glasgow Coma Scale score), deemed to be of ischemic origin, after ruling out other causes (such as hydrocephalus, toxic-metabolic disturbances, or seizures); or identification of a new cerebral infarction on CT or MRI imaging.
Time frame: 30 days after onset
Montreal Cognitive Assessment (MoCA)
Cognitive function was evaluated using the Montreal Cognitive Assessment (MoCA), a standardized screening tool with scores ranging from 0 to 30, where higher scores indicate better cognitive performance and lower scores reflect greater cognitive impairment. Measure mean score or median compared between groups. And the rate of MoCA score of 20 or less between groups.
Time frame: 90-day follow-up visit
Cerebral Vasospasm
Incidence of moderate and severe radiographic cerebral vasospasm (catheter angiogram, CTA, MRA) or incidence OR moderate and severe vasospasm by transcranial doppler (TCD) criteria.
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
Time frame: Participants will be followed for the duration of the hospital stay, an expected average of 2 weeks
Glasgow Coma Score(GCS)
The Glasgow Outcome Scale was used as secondary outcomes. The level of consciousness was assessed using the Glasgow Coma Scale (GCS), a standardized scale ranging from 3 to 15, where higher scores indicate a better neurological status (i.e., a higher level of consciousness), and lower scores reflect more severe impairment.
Time frame: Enrollment, 30 days after onset, and 90-day follow-up visit
The modified Rankin Scale (mRS)
Shift analysis of mRS scores at 30 days after onset. The modified Rankin Scale (mRS) is a commonly used scale for measuring the degree of disability or dependence in the daily activities of people who have suffered a stroke or other causes of neurological disability. (Score Description: 0---No symptoms at all. 1---No significant disability despite symptoms; able to carry out all usual duties and activities. 2---Slight disability; unable to carry out all previous activities, but able to look after own affairs without assistance. 3---Moderate disability; requiring some help, but able to walk without assistance. 4--- Moderately severe disability; unable to walk without assistance and unable to attend to own bodily needs without assistance. 5---Severe disability; bedridden, incontinent and requiring constant nursing care and attention. 6---Dead. The higher scores indicate worse functional disability and lower scores reflect better functional independence.
Time frame: 30 days after onset
modified Rankin Scale (mRS)
The rate of modified Rankin Scale (mRS) score \> 3. The modified Rankin Scale (mRS) is a commonly used scale for measuring the degree of disability or dependence in the daily activities of people who have suffered a stroke or other causes of neurological disability. (Score Description: 0---No symptoms at all. 1---No significant disability despite symptoms; able to carry out all usual duties and activities. 2---Slight disability; unable to carry out all previous activities, but able to look after own affairs without assistance. 3---Moderate disability; requiring some help, but able to walk without assistance. 4--- Moderately severe disability; unable to walk without assistance and unable to attend to own bodily needs without assistance. 5---Severe disability; bedridden, incontinent and requiring constant nursing care and attention. 6---Dead. The higher scores indicate worse functional disability and lower scores reflect better functional independence.
Time frame: 30 days after onset
Barthel Index (BI) score
Activities of daily living were evaluated using the Barthel Index (BI), a functional assessment scale ranging from 0 to 100, where higher scores indicate greater independence in daily activities and lower scores reflect more severe functional dependence.
Time frame: 90-day follow-up visit
All-cause mortality
Death caused by any reason.
Time frame: 90-day follow-up visit
Complication of severe dependent survival
eg, chest or other infections
Time frame: 90-day follow-up visit
Treated aneurysm rebleeding
Treated aneurysm rebleeding
Time frame: 90-day follow-up visit
Probable or definite bleed from another aneurysm
Probable or definite bleed from another aneurysm
Time frame: 90-day follow-up visit
Incidence of adverse events
Ischaemic stroke, Other intracranial haemorrhage, Cardiac, Cancer, Suicide, Renal failure, Infections not related to dependent survival, Other causes (eg, trauma, perforated ulcer, pulmonary embolus, neurodegenerative)
Time frame: 90-day follow-up visit