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Aneurysmal Subarachnoid Hemorrhage (aSAH)NCT07343232

Correcting Hypocapnia in Aneurysmal Subarachnoid Hemorrhage.

An observational study of Aneurysmal Subarachnoid Hemorrhage (aSAH), run by The Chinese University of Hong Kong, Shenzhen at 1 site in China.

Not yet recruiting

Opening soon. The study is approved but enrolment has not started yet. Sites may already take enquiries.

Sites and contacts
Official record
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Trial summary

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… Read more about this study

Who is it for?
Ages 18 years and older
What is being tested?
Normobaric Facemask Oxygen
How many people
80 participants
Where
1 siteChina
Study dates
1 Jan 2026to 30 Oct 2026
How long will I take part?
90 Days
Phase
Observational
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Study population: Aneurysmal Subarachnoid Hemorrhage Patients with Hypocapnia.

Who may be able to join

  • Age > 18 years.
  • Confirmed diagnosis of aneurysmal subarachnoid hemorrhage (aSAH), with the presence of an aneurysm verified by computed tomography (CT), CT angiography (CTA), or digital subtraction angiography (DSA).
  • Hunt-Hess grade II-IV.
  • Presence of hypocapnia on arterial blood gas analysis, defined as PaCO2 < 35 mmH;
  • PaO2 > 90 mmHg.

Who cannot join

  • Presence of brain herniation or refractory intracranial hypertension, defined as a baseline intracranial pressure (ICP) > 25 mmHg that responds poorly to conventional ICP-lowering therapy;
  • Primary respiratory diseases (e.g., chronic obstructive pulmonary disease, severe asthma) known to cause chronically elevated baseline PaCO2;
  • Severe acid-base disturbances other than respiratory alkalosis.
  • Severe cardiac insufficiency, severe hepatic or renal dysfunction, malignant tumors, or other severe comorbidities that significantly impact prognosis;
  • Before the onset of the disease, the mRS score was greater than 2, and there were other factors causing disability.
  • Life expectancy < 3 months;
  • Any other condition deemed by the investigator to pose a high risk warranting exclusion.

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

Xinyu Yang, MD contact

18622766038

cuhkshzhyang@outlook.com

China1 site

  • School of Medicine Chinese University of Hong Kong-SHENZHEN

    Shenzhen, Guangdong, 518000

    Xinyu Yang, MD, 18622766038, cuhkshzhyang@outlook.com

    Xinyu Yang, MD

Other trials in China

About this study

Official title: Safety and Efficacy of Normobaric Facemask Oxygen for Hypocapnia in Aneurysmal Subarachnoid Hemorrhage(FOCAL): A Prospective, Multicenter, Proof-of-concept Pilot Study

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.

Read the detailed description

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.

Being tested
Normobaric Facemask Oxygen, control group
Keywords
Aneurysmal Subarachnoid Hemorrhage (aSAH), Hypocapnia
Medical subject headings
Subarachnoid Hemorrhage, Hypocapnia

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Normobaric Facemask OxygenBehavioural

    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.

  • control groupBehavioural

    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.

Study groups in NCT07343232
Study groupRoleWhat they receive
Normobaric Facemask OxygenPatients who received oxygen via a rebreathing facemask (ensuring no one-way valve is present), with a fractional inspired oxygen (FiO2) of 25-40% and an oxygen flow rate of ≤ 5 L/min.
Receives: Behavioral: Normobaric Facemask Oxygen
Control groupPatients who received oxygen via nasal cannula or did not receive oxygen therapy.
Receives: Behavioral: control group

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. 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.

    Measured: 90-day follow-up visit

  2. 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.

    Measured: 30 days after onset

Secondary outcomes (11)

  1. 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.

    Measured: 90-day follow-up visit

  2. 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.

    Measured: Participants will be followed for the duration of the hospital stay, an expected average of 2 weeks

  3. 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.

    Measured: Enrollment, 30 days after onset, and 90-day follow-up visit

  4. 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.

    Measured: 30 days after onset

  5. 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.

    Measured: 30 days after onset

  6. 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.

    Measured: 90-day follow-up visit

  7. All-cause mortality

    Death caused by any reason.

    Measured: 90-day follow-up visit

  8. Complication of severe dependent survival

    eg, chest or other infections

    Measured: 90-day follow-up visit

  9. Treated aneurysm rebleeding

    Treated aneurysm rebleeding

    Measured: 90-day follow-up visit

  10. Probable or definite bleed from another aneurysm

    Probable or definite bleed from another aneurysm

    Measured: 90-day follow-up visit

  11. 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)

    Measured: 90-day follow-up visit

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted15 Jan 2026
  2. Study start1 Jan 2026 (estimated)
  3. Primary completion30 Sep 2026 (estimated)
  4. Study completion30 Oct 2026 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Observational
Observational model
Cohort
Time perspective
Prospective
Enrolment
80 participants (estimated)
Target duration
90 Days
IDs, dates and publications
ClinicalTrials.gov ID
NCT07343232
Sponsor's protocol ID
CUHKShenzhen
Status last verified
Jan 2026
First submitted
17 Dec 2025
Last updated
15 Jan 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
Undecided

Publications

  • Yang L, Yuan D, Luo Z, Li Y, Zhu X. The low-flow mask oxygen could be a more effective, comfortable, and easy-to-follow treatment for psychogenic hyperventilation syndrome: A double-blind, randomized controlled trial. Int Emerg Nurs. 2025 Aug;81:101636. doi: 10.1016/j.ienj.2025.101636. Epub 2025 Jun 17.

    PubMed 40532319

  • Darkwah Oppong M, Wrede KH, Muller D, Santos AN, Rauschenbach L, Dinger TF, Ahmadipour Y, Pierscianek D, Chihi M, Li Y, Deuschl C, Sure U, Jabbarli R. PaCO2-management in the neuro-critical care of patients with subarachnoid hemorrhage. Sci Rep. 2021 Sep 28;11(1):19191. doi: 10.1038/s41598-021-98462-2.

    PubMed 34584136

  • Cai G, Zhang X, Ou Q, Zhou Y, Huang L, Chen S, Zeng H, Jiang W, Wen M. Optimal Targets of the First 24-h Partial Pressure of Carbon Dioxide in Patients with Cerebral Injury: Data from the MIMIC-III and IV Database. Neurocrit Care. 2022 Apr;36(2):412-420. doi: 10.1007/s12028-021-01312-2. Epub 2021 Jul 30.

    PubMed 34331211

  • Su R, Li HL, Wang YM, Zhang L, Zhou JX. Association of dynamic changes in arterial partial pressure of carbon dioxide with neurological outcomes in aneurysmal subarachnoid hemorrhage. Heliyon. 2024 Oct 10;10(20):e39197. doi: 10.1016/j.heliyon.2024.e39197. eCollection 2024 Oct 30.

    PubMed 39640813

  • Carrera E, Schmidt JM, Fernandez L, Kurtz P, Merkow M, Stuart M, Lee K, Claassen J, Sander Connolly E, Mayer SA, Badjatia N. Spontaneous hyperventilation and brain tissue hypoxia in patients with severe brain injury. J Neurol Neurosurg Psychiatry. 2010 Jul;81(7):793-7. doi: 10.1136/jnnp.2009.174425. Epub 2009 Dec 3.

    PubMed 19965840

  • Coles JP, Fryer TD, Coleman MR, Smielewski P, Gupta AK, Minhas PS, Aigbirhio F, Chatfield DA, Williams GB, Boniface S, Carpenter TA, Clark JC, Pickard JD, Menon DK. Hyperventilation following head injury: effect on ischemic burden and cerebral oxidative metabolism. Crit Care Med. 2007 Feb;35(2):568-78. doi: 10.1097/01.CCM.0000254066.37187.88.

    PubMed 17205016

  • Coles JP, Minhas PS, Fryer TD, Smielewski P, Aigbirihio F, Donovan T, Downey SP, Williams G, Chatfield D, Matthews JC, Gupta AK, Carpenter TA, Clark JC, Pickard JD, Menon DK. Effect of hyperventilation on cerebral blood flow in traumatic head injury: clinical relevance and monitoring correlates. Crit Care Med. 2002 Sep;30(9):1950-9. doi: 10.1097/00003246-200209000-00002.

    PubMed 12352026

  • Robba C, Battaglini D, Abbas A, Sarrio E, Cinotti R, Asehnoune K, Taccone FS, Rocco PR, Schultz MJ, Citerio G, Stevens RD, Badenes R; ENIO collaborators. Clinical practice and effect of carbon dioxide on outcomes in mechanically ventilated acute brain-injured patients: a secondary analysis of the ENIO study. Intensive Care Med. 2024 Feb;50(2):234-246. doi: 10.1007/s00134-023-07305-3. Epub 2024 Jan 31.

    PubMed 38294526

  • Williamson CA, Sheehan KM, Tipirneni R, Roark CD, Pandey AS, Thompson BG, Rajajee V. The Association Between Spontaneous Hyperventilation, Delayed Cerebral Ischemia, and Poor Neurological Outcome in Patients with Subarachnoid Hemorrhage. Neurocrit Care. 2015 Dec;23(3):330-8. doi: 10.1007/s12028-015-0138-5.

    PubMed 25846710

Questions about this trial

What is this clinical trial studying?

An observational study of Aneurysmal Subarachnoid Hemorrhage (aSAH), run by The Chinese University of Hong Kong, Shenzhen at 1 site in China.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 5 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: opening soon, as of the sponsor's last update on 15 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in China. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Xinyu Yang, MD (18622766038, cuhkshzhyang@outlook.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

modified Rankin Scale (mRS) >3 (time frame: 90-day follow-up visit). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07343232, which also lists 9 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Jan 2026.

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