TY - JOUR
T1 - Effect of perfusion pressure on cerebral blood flow during normothermic cardiopulmonary bypass
AU - Newman, Mark F.
AU - Croughwell, Narda D.
AU - White, William D.
AU - Lowry, Edward
AU - Baldwin, Beatrice I.
AU - Clements, Fiona M.
AU - Davis, Robert D.
AU - Jones, Robert H.
AU - Amory, David W.
AU - Reves, Joseph G.
PY - 1996/11/1
Y1 - 1996/11/1
N2 - Background: We have recently shown that during hypothermic cardiopulmonary bypass (CPB), cerebral autoregulation has a positive slope such that for every 10 mm Hg change in pressure, a 0.86 mL · 100 g-1 · min-1 change in cerebral blood flow (CBF) is predicted. The purpose of this study was to define the influence of mean arterial blood pressure (MAP) on CBF during normothermic CPB. Methods and Results: CBF was measured by use of 133Xe washout and α-stat blood gas management during nonpulsatile CPB. CBF measurements were made at a pump flow of 2.4 L · min-1 · m-2 at stable normothermia and ≃15 minutes later after the MAP was increased or decreased ≤20%. A third data set was recorded after the pressure was returned to the initial value. Forty-five patients were entered into the study. Temperature was held constant. We found a significant effect (P=.016) of change in MAP on change in CBF during normothermic CPB. For a 10 mm Hg increase in MAP, an increase in CBF of 1.78 mL · 100 g-1 · min-1 is predicted. Along with change in CBF, significant increases in both cerebral metabolic rate and cerebral oxygen delivery were observed. Conclusions: This information, along with our previous data, shows that autoregulation during CPB has a positive slope that is greater with normothermia than hypothermia. Although it is unlikely that these small changes in flow are an important primary effect in the development of hypoperfusion, increased metabolic rate with increased CBF may indicate pressure-dependent collateral flow potentially in regions embolized during CPB.
AB - Background: We have recently shown that during hypothermic cardiopulmonary bypass (CPB), cerebral autoregulation has a positive slope such that for every 10 mm Hg change in pressure, a 0.86 mL · 100 g-1 · min-1 change in cerebral blood flow (CBF) is predicted. The purpose of this study was to define the influence of mean arterial blood pressure (MAP) on CBF during normothermic CPB. Methods and Results: CBF was measured by use of 133Xe washout and α-stat blood gas management during nonpulsatile CPB. CBF measurements were made at a pump flow of 2.4 L · min-1 · m-2 at stable normothermia and ≃15 minutes later after the MAP was increased or decreased ≤20%. A third data set was recorded after the pressure was returned to the initial value. Forty-five patients were entered into the study. Temperature was held constant. We found a significant effect (P=.016) of change in MAP on change in CBF during normothermic CPB. For a 10 mm Hg increase in MAP, an increase in CBF of 1.78 mL · 100 g-1 · min-1 is predicted. Along with change in CBF, significant increases in both cerebral metabolic rate and cerebral oxygen delivery were observed. Conclusions: This information, along with our previous data, shows that autoregulation during CPB has a positive slope that is greater with normothermia than hypothermia. Although it is unlikely that these small changes in flow are an important primary effect in the development of hypoperfusion, increased metabolic rate with increased CBF may indicate pressure-dependent collateral flow potentially in regions embolized during CPB.
KW - blood pressure
KW - brain
KW - bypass
KW - cardiopulmonary bypass
KW - cerebrovascular circulation
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M3 - Article
C2 - 8901774
AN - SCOPUS:10244260397
SN - 0009-7322
VL - 94
SP - II353-II357
JO - Circulation
JF - Circulation
IS - 9 SUPPL.
ER -