title: Cerebral oxygen metabolism during total body flow and antegrade cerebral perfusion at deep and moderate hypothermia.
abstract: The aim of this study is to evaluate the effect of temperature on cerebral oxygen metabolism at total body flow bypass and antegrade cerebral perfusion (ACP). Neonatal piglets were put on cardiopulmonary bypass (CPB) with the initial flow rate of 200mL/kg/min. After cooling to 18°C (n=6) or 25°C (n=7), flow was reduced to 100mL/kg/min (half-flow, HF) for 15min and ACP was initiated at 40mL/kg/min for 45min. Following rewarming, animals were weaned from bypass and survived for 4h. At baseline, HF, ACP, and 4 h post-CPB, cerebral blood flow (CBF) was measured using fluorescent microspheres. Cerebral oxygen extraction (CEO(2) ) and cerebral metabolic rate of oxygen (CMRO(2) ) were monitored. Regional cranial oxygen saturation (rSO(2) ) was continuously recorded throughout the procedure using near-infrared spectroscopy. At 18°C, CBF trended lower at HF and ACP and matched baseline after CPB. CEO(2) trended lower at HF and ACP, and trended higher after CPB compared with baseline. CMRO(2) at ACP matched that at HF. Cranial rSO(2) was significantly greater at HF and ACP (P<0.001, P<0.001) and matched baseline after CPB. At 25°C, CBF trended lower at HF, rebounded and trended higher at ACP, and matched baseline after CPB. CEO(2) was equal at HF and ACP and trended higher after CPB compared with baseline. CMRO(2) at ACP was greater than that at HF (P=0.001). Cranial rSO(2) was significantly greater at HF (P=0.01), equal at ACP, and lower after CPB (P=0.03). Lactate was significantly higher at all time points (P=0.036, P<0.001, and P<0.001). ACP provided sufficient oxygen to the brain at a total body flow rate of 100mL/kg/min at deep hypothermia. Although ACP provided minimum oxygenation to the brain which met the oxygen requirement, oxygen metabolism was altered during ACP at moderate hypothermia. ACP strategy at moderate hypothermia needs further investigation.
authors.affiliation: Department of Cardiothoracic Surgery, Stanford University, Stanford, CA, USA. tsasakister@gmail.com
authors.forename: Takashi
authors.initials: T
authors.lastname: Sasaki
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Boni
authors.forename: R Kirk
authors.initials: RK
authors.lastname: Riemer
authors.forename: John T
authors.initials: JT
authors.lastname: Yeung
authors.forename: Chandra
authors.initials: C
authors.lastname: Ramamoorthy
authors.forename: Ryan
authors.initials: R
authors.lastname: Beckman
authors.forename: Carl
authors.initials: C
authors.lastname: Gisner
authors.forename: Paul
authors.initials: P
authors.lastname: Shuttleworth
authors.forename: Frank L
authors.initials: FL
authors.lastname: Hanley
authors.forename: V Mohan
authors.initials: VM
authors.lastname: Reddy
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001783:Blood Flow Velocity; D001794:Blood Pressure; D001921:Brain / Q000098:blood supply* / Q000378:metabolism*; D002315:Cardiopulmonary Bypass; D002560:Cerebrovascular Circulation; D007036:Hypothermia, Induced; D019344:Lactic Acid / Q000097:blood; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D010477:Perfusion; D013050:Spectrometry, Fluorescence; D019265:Spectroscopy, Near-Infrared; D013552:Swine; D013997:Time Factors
chemical_list: D019344:Lactic Acid; D010100:Oxygen