NCT07343232

Correcting Hypocapnia in Aneurysmal Subarachnoid Hemorrhage.

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

• Status: Not Yet Recruiting
• Phase: —
• Study type: Observational
• Enrollment: 80 (estimated)
• Sponsor: The Chinese University of Hong Kong, Shenzhen · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

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 investigate the safety and efficacy of normobaric facemask oxygen for hypocapnia in aSAH.

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.

Conditions

• Aneurysmal Subarachnoid Hemorrhage (aSAH)

Interventions

Type	Name	Description
BEHAVIORAL	Normobaric Facemask Oxygen	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.
BEHAVIORAL	control group	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.

Timeline

• Start date: 2026-01-01
• Primary completion: 2026-09-30
• Completion: 2026-10-30
• First posted: 2026-01-15
• Last updated: 2026-01-15

Locations

1 site across 1 country: China