{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,21]],"date-time":"2026-07-21T14:04:17Z","timestamp":1784642657635,"version":"3.55.0"},"reference-count":28,"publisher":"BMJ","issue":"7","license":[{"start":{"date-parts":[[2026,7,21]],"date-time":"2026-07-21T00:00:00Z","timestamp":1784592000000},"content-version":"unspecified","delay-in-days":20,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"name":"Beijing Natural Science Foundation","award":["7262053"],"award-info":[{"award-number":["7262053"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["62376168"],"award-info":[{"award-number":["62376168"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["BMJ Open"],"accepted":{"date-parts":[[2026,7,13]]},"published-print":{"date-parts":[[2026,7]]},"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Cerebral hyperperfusion syndrome (CHS) is a severe complication following carotid endarterectomy (CEA). During emergence from general anaesthesia, residual anaesthetics induce mild respiratory depression and carbon dioxide accumulation, exacerbating hyperperfusion risks via hypercapnia-induced cerebral vasodilation. High-flow nasal cannula (HFNC) effectively reduces excessively elevated pressure of arterial carbon dioxide via multiple mechanisms including anatomical dead space washout. This trial aims to evaluate the effects of HFNC versus conventional mask oxygen therapy on ipsilateral cerebral haemodynamics during the immediate post-extubation phase in patients undergoing CEA.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods and analysis<\/jats:title>\n                    <jats:p>This single-centre, randomised controlled trial will allocate 66 adult patients scheduled for elective CEA in a 1:1 ratio to receive either HFNC or a conventional oxygen mask for 10\u2009min immediately following tracheal extubation. The primary outcome is the ipsilateral relative middle cerebral artery blood flow velocity (rMCAv) at 10 minutes post-extubation. Secondary outcomes encompass continuous high-frequency trajectories of ipsilateral rMCAv and invasive arterial blood pressure, their haemodynamic variability (coefficient of variation) and hyperperfusion burden (area under the curve), absolute changes in arterial blood gases (ABG) and clinical outcomes evaluated up to hospital discharge (including abnormal ipsilateral cerebral hyperperfusion, postoperative headache, CHS, incidence of postoperative acute ischaemic stroke or transient ischaemic attack and length of stay). Longitudinal high-frequency data will be analysed using linear mixed-effects models while pre-intervention and post-intervention ABG variations will be evaluated via analysis of covariance.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Ethics and dissemination<\/jats:title>\n                    <jats:p>The protocol (V.2.0, 30 June 2025) complies with the Declaration of Helsinki and was approved by the Institutional Review Board of Xuanwu Hospital, Capital Medical University (LYS[2025]-NO.147-002). Written informed consent will be obtained from all participants prior to inclusion. Results will be submitted for publication in peer-reviewed journals.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Trial registration number<\/jats:title>\n                    <jats:p>ChiCTR2500105199.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjopen-2026-120038","type":"journal-article","created":{"date-parts":[[2026,7,21]],"date-time":"2026-07-21T13:40:25Z","timestamp":1784641225000},"page":"e120038","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Efficacy of high-flow nasal cannula versus conventional face mask oxygen therapy on ipsilateral cerebral haemodynamics during the immediate post-extubation phase following carotid endarterectomy: protocol for a randomised controlled 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