title: Blood flow measurements within optic nerve head during on-pump cardiovascular operations. A window to the brain?
abstract: This observational study is conducted to demonstrate optic nerve head (ONH) blood flow alterations during extracorporeal circulation (ECC) in routine on-pump cardiovascular operations in order to evaluate the perfusion status of important autoregulatory tissue vascular beds during moderate hypothermia. Twenty-one patients free from eye disease were prospectively enrolled in our database. Perioperative ONH blood flow measurements were performed using a hand-held portable ocular laser Doppler flowmeter just after administration of general anesthesia and during cardiopulmonary bypass (CPB) upon the lowest temperature point of moderate hypothermia. Important operative flow variables were correlated to optic nerve blood flow during surgical phases. Statistical analysis showed significant reduction of 32.1 ± 14.5% of mean ONH blood flow in phase 2 (P < 0.0001) compared to the reference flow values of phase 1. A negative univariate association between ECC time and ONH blood flow in phase 2 (P = 0.031) is noted. This angiokinetic approach can detect changes of flow within autoregulatory vascular tissue beds like ONH, thus creating a 'window' on cerebral microvasculature. ONH blood flow is reduced during CPB. Our data suggest that it is of paramount importance to avoid extracorporeal prolongation even in moderate hypothermic cardiovascular operations.
authors.affiliation: Department of Cardiothoracic Surgery, University Hospital of Thessaly, Larisa, Greece. jonenek@yahoo.com
authors.forename: Ioannis
authors.initials: I
authors.lastname: Nenekidis
authors.forename: Martial
authors.initials: M
authors.lastname: Geiser
authors.forename: Charles
authors.initials: C
authors.lastname: Riva
authors.forename: Constantin
authors.initials: C
authors.lastname: Pournaras
authors.forename: Evangelia
authors.initials: E
authors.lastname: Tsironi
authors.forename: Georgios
authors.initials: G
authors.lastname: Vretzakis
authors.forename: Vasilios
authors.initials: V
authors.lastname: Mitilis
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Tsilimingas
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D002560:Cerebrovascular Circulation; D004867:Equipment Design; D005260:Female; D006115:Greece; D006706:Homeostasis; D006801:Humans; D007036:Hypothermia, Induced; D007511:Ischemia / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D017078:Laser-Doppler Flowmetry / Q000295:instrumentation; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods*; D009898:Optic Disk / Q000098:blood supply*; D011446:Prospective Studies; D012039:Regional Blood Flow; D014463:Ultrasonography