title: Venous obstruction and cerebral perfusion during experimental cardiopulmonary bypass.
abstract: To investigate the effects on cerebral perfusion by experimental venous congestion of the superior vena cava (SVC) during bicaval cardiopulmonary bypass (CPB) at 34 °C, pigs were subjected to SVC obstruction at levels of 75%, 50%, 25% and 0% of baseline SVC flow at two arterial flow levels (low, LQ, high, HQ). The cerebral perfusion was examined with near-infrared spectroscopy (NIRS), cerebral microdialysis and blood gas analysis. SVC obstruction caused significant decreases in the NIRS tissue oxygenation index (TOI) and in SVC oxygen saturations (P<0.05, both groups), while the mixed venous saturation was decreased only in the LQ group. Sagittal sinus venous saturations were measured in the HQ group and found significantly reduced in response to venous congestion (P<0.05). No microdialysis changes were seen at the group level, however, individual ischemic patterns in terms of concomitant venous desaturation, decreased TOI and increased lactate/pyruvate occurred in both groups. The total venous drainage remained stabile throughout the experiment, indicating increased flow in the inferior vena cava cannula. The results indicate that SVC congestion may impair cerebral perfusion especially in the case of compromised arterial flow during CPB. Reduced SVC cannula flow may pass undetected during bicaval CPB, if SVC flow is not specifically monitored.
authors.affiliation: Department of Surgical Sciences, Section of Cardiothoracic Surgery and Anaesthesiology, Uppsala University Hospital, Entrance 50/7th Floor, SE-751 85 Uppsala, Sweden. thomas.tovedal@gmail.com
authors.forename: Thomas
authors.initials: T
authors.lastname: Tovedal
authors.forename: Ove
authors.initials: O
authors.lastname: Jonsson
authors.forename: Vitas
authors.initials: V
authors.lastname: Zemgulis
authors.forename: Gunnar
authors.initials: G
authors.lastname: Myrdal
authors.forename: Stefan
authors.initials: S
authors.lastname: Thelin
authors.forename: Fredrik
authors.initials: F
authors.lastname: Lennmyr
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000097:blood; D001784:Blood Gas Analysis; D001786:Blood Glucose / Q000378:metabolism; D002545:Brain Ischemia / Q000097:blood / Q000209:etiology* / Q000503:physiopathology; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D002496:Central Venous Pressure; D002560:Cerebrovascular Circulation; D004195:Disease Models, Animal; D005990:Glycerol / Q000097:blood; D007036:Hypothermia, Induced; D019344:Lactic Acid / Q000097:blood; D017551:Microdialysis; D016343:Monitoring, Intraoperative / Q000379:methods; D010100:Oxygen / Q000097:blood; D019289:Pyruvic Acid / Q000097:blood; D012039:Regional Blood Flow; D019265:Spectroscopy, Near-Infrared; D013479:Superior Vena Cava Syndrome / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D013552:Swine; D014682:Vena Cava, Inferior / Q000503:physiopathology
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D019344:Lactic Acid; D019289:Pyruvic Acid; D005990:Glycerol; D010100:Oxygen