Comparison of pH-state and Alpha-stat Cardiopulmonary Bypass on Cerebral Oxygenation and Blood Flow in Relation to Hypothermic Circulatory Arrest in Piglets 

1998 ◽  
Vol 89 (1) ◽  
pp. 110-118 ◽  
Author(s):  
Dean C. Kurth ◽  
Maureen M. O'Rourke ◽  
Irene B. O'Hara
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Cardiopulmonary Bypass ◽  
Water Content ◽  
Adenosine Triphosphate ◽  
Half Life ◽  
Circulatory Arrest ◽  
Hypothermic Circulatory Arrest ◽  
Ph Stat ◽  
Hypothermic Arrest

Background Deep hypothermic circulatory arrest is used in neonatal cardiac surgery. Recent work has suggested improved neurologic recovery after deep hypothermic arrest with pH-stat cardiopulmonary bypass (CPB) compared with alpha-stat CPB. This study examined cortical oxygen saturation (ScO2), cortical blood flow (CBF), and cortical physiologic recovery in relation to deep hypothermic arrest with alpha-stat or pH-stat CPB. Methods Sixteen piglets were cooled with pH-stat or alpha-stat CPB to 19 degrees C (cortex) and subjected to 60 min of circulatory arrest, followed by CPB reperfusion and rewarming and separation from CPB. Near infrared spectroscopy and laser Doppler flowmetry were used to monitor ScO2 and CBF. Cortical physiologic recovery was assessed 2 h after the piglets were separated from CPB by cortical adenosine triphosphate concentrations, cortical water content, CBF, and ScO2. Results During CPB cooling, ScO2 increased more with pH-stat than with alpha-stat bypass (123 +/- 33% vs. 80 +/- 25%); superficial and deep CBF were also greater with pH-stat than with alpha-stat bypass (22 +/- 25% vs. -56 +/- 22%, 3 +/- 19% vs. -29 +/- 28%). During arrest, ScO2 half-life was greater with pH-stat than with alpha-stat bypass (10 +/- 2 min vs. 7 +/- 2 min), and cortical oxygen consumption lasted longer with pH-stat than with alpha-stat bypass (36 +/- 8 min vs. 25 +/- 8 min). During CPB reperfusion, superficial and deep CBF were less with alpha-stat than with pH-stat bypass (-40 +/- 22% vs. 10 +/- 39%, -38 +/- 28% vs. 5 +/- 28%). After CPB, deep cortical adenosine triphosphate and CBF were less with alpha-stat than with pH-stat bypass (11 +/- 6 pmole/mg vs. 17 +/- 8 pmole/mg, -24 +/- 16% vs. 16 +/- 32%); cortical water content was greater with alpha-stat than with pH-stat bypass (superficial: 82.4 +/- 0.3% vs. 81.8 +/- 1%, deep: 79.1 +/- 2% vs. 78 +/- 1.6%). Conclusions Cortical deoxygenation during hypothermic arrest was slower after pH-stat CPB. pH-stat bypass increased the prearrest ScO2 and arrest ScO2 half-life, to increase the cortical oxygen supply and slow cortical oxygen consumption. Improved cortical physiologic recovery after hypothermic arrest was suggested with pH-stat management.

scholarly journals Effects of MK-801 and NBQX on Acute Recovery of Piglet Cerebral Metabolism after Hypothermic Circulatory Arrest

1994 ◽  
Vol 14 (1) ◽  
pp. 156-165 ◽  
Author(s):  
Mitsuru Aoki ◽  
Fumikazu Nomura ◽  
Michael E. Stromski ◽  
Miles K. Tsuji ◽  
James C. Fackler ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Oxygen Consumption ◽  
Cardiopulmonary Bypass ◽  
Circulatory Arrest ◽  
High Energy ◽  
Hypothermic Circulatory Arrest ◽  
Cerebral Oxygen ◽  
High Energy Phosphates ◽  
Mk 801

Brain protection during open heart surgery in the neonate and infant remains inadequate. Effects of the excitatory neurotransmitter antagonists MK-801 and NBQX on recovery of brain cellular energy state and metabolic rates were evaluated in 34 4-week-old piglets (10 MK-801, 10 NBQX, 14 controls) undergoing cardiopulmonary bypass and hypothermic circulatory arrest at 15°C nasopharyngeal temperature for 1 h, as is used clinically for repair of congenital heart defects. MK-801 (dizocilpine) (0.75 mg/kg) or NBQX [2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo( F)quinoxaline] (25 mg/kg) was given intravenously before cardiopulmonary bypass. Equivalent doses were placed in the cardiopulmonary bypass prime plus continuous infusions after reperfusion (0.15 mg kg−1h−1 and 5 mg kg−1h−1). Changes in high-energy phosphate concentrations and pH were analyzed by magnetic resonance spectroscopy in 17 animals until 225 min after reperfusion. Cerebral blood flow determined by radioactive microspheres as well as cerebral oxygen and glucose consumption were studied in 17 other animals. Cerebral blood flow and oxygen consumption were depressed relative to control by both MK-801 and NBQX at baseline. Recovery of phosphocreatine (p = 0.010), ATP (p = 0.030), and intracellular pH (p = 0.004) was accelerated by MK-801 and retarded by NBQX over the 45 min of rewarming reperfusion and the first hour of normothermic reperfusion. The final recovery of ATP at 3 h and 45 min reperfusion was significantly reduced by NBQX (46 ± 26% baseline, mean ± SD) versus control (81 ± 19%) and MK-801 (75 ± 8%) (p = 0.030). Cerebral oxygen consumption recovered to 105 ± 30% baseline in group MK-801 and 94 ± 31% in control but only to 61 ± 22% in group NBQX (p = 0.070). Cerebral blood flow stayed significantly lower in group NBQX relative to control. Thus, MK-801 accelerates recovery of cerebral high-energy phosphates and metabolic rate after cardiopulmonary bypass and hypothermic circulatory arrest in the immature animal. At the dosage used NBQX exerts an adverse effect.

Oxygen and the Gradients of Life

2011 ◽  
pp. 88-93
Author(s):  
James R. Munis
Keyword(s):  
Oxygen Consumption ◽  
Circulatory Arrest ◽  
Cellular Metabolism ◽  
Deep Hypothermic Circulatory Arrest ◽  
Hypothermic Circulatory Arrest ◽  
Live Cells ◽  
Organ Systems ◽  
The Dead ◽  
The Difference ◽  
Hypothermic Arrest

Physiologically, what is the difference between a patient undergoing deep hypothermic circulatory arrest and another patient who has died and cooled to the same temperature? The answer resides inside the cells. During hypothermic arrest, physiologic functions of whole-organ systems are temporarily arrested, but the cells are still busy. Cellular metabolism is also slowed, but it's not completely stopped. One difference between the hypothermic-arrest patient and the dead patient is that the former has live cells and the latter has dead cells. And furthermore, one of the differences between live cells and dead cells is that live cells maintain certain important gradients across their membranes. Another difference is that dead cells have no metabolism. We often refer to cellular metabolism as ‘respiration,’ and we measure it by calculating how much oxygen is being used. This brings us to oxygen. Why do we define cellular metabolism in terms of oxygen consumption?

A vulnerable interval for cerebral injury—comparison of hypothermic circulatory arrest and low flow cardiopulmonary bypass

1993 ◽  
Vol 3 (3) ◽  
pp. 287-298 ◽  
Author(s):  
Craig K. Mezrow ◽  
Peter S. Midulla ◽  
Ali M. Sadeghi ◽  
Otto Dapunt ◽  
Alejandro Gandsas ◽  
...  
Keyword(s):  
Congenital Heart Disease ◽  
Heart Disease ◽  
Cardiopulmonary Bypass ◽  
Congenital Heart ◽  
Circulatory Arrest ◽  
Hypothermic Circulatory Arrest ◽  
Cerebral Injury ◽  
Low Flow ◽  
Increasing Risk ◽  
Hypothermic Arrest

Over the past two decades, advances in equipment used for cardiopulmonary bypass and in operative techniques have resulted in a tremendous decrease in the mortality of patients undergoing surgical repair of congenital heart disease utilizing hypothermic circulatory arrest. Despite the widespread use of hypothermic arrest, opinion is not unanimous with regard to its safety. Previous studies which have examined neurological outcome following repair of congenital heart disease in infancy have generally agreed that when the period of arrest exceeds 60 minutes, there is increasing risk of cerebral injury.

The effects of cardiopulmonary bypass and deep hypothermic circulatory arrest on blood viscoelasticity and cerebral blood flow in a neonatal piglet model

Perfusion ◽  
2000 ◽  
Vol 15 (2) ◽  
pp. 121-128 ◽  
Author(s):  
Akif Ündar ◽  
William K Vaughn ◽  
John H Calhoon
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Cardiopulmonary Bypass ◽  
Regional Cerebral Blood Flow ◽  
Circulatory Arrest ◽  
Deep Hypothermic Circulatory Arrest ◽  
Hypothermic Circulatory Arrest ◽  
Regional Cerebral Blood ◽  
Neonatal Piglet ◽  
Arterial Blood

The purpose of this study is to determine the effects of cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) on the viscoelasticity (viscosity and elasticity) of blood and global and regional cerebral blood flow (CBF) in a neonatal piglet model. After initiation of CPB, all animals ( n = 3) were subjected to core cooling for 20 min to reduce the piglets’ nasopharyngeal temperatures to 18°C. This was followed by 60 min of DHCA, then 45 min of rewarming. During cooling and rewarming, the alpha-stat technique was used. Arterial blood samples were taken for viscoelasticity measurements and differently labeled microspheres were injected at pre-CPB, pre- and post-DHCA, 30 and 60 min after CPB for global and regional cerebral blood flow calculations. Viscosity and elasticity were measured at 2 Hz, 22°C and at a strain of 0.2, 1, and 5 using a Vilastic-3 Viscoelasticity Analyzer. Elasticity of blood at a strain = 1 decreased to 32%, 83%, 57%, and 61% ( p = 0.01, ANOVA) while the viscosity diminished 8.4%, 38%, 22%, 26% compared to the baseline values ( p = 0.01, ANOVA) at pre-DHCA, post-DHCA, 30 and 60 min after CPB, respectively. The viscoelasticity of blood at a strain of 0.2 and 5 also had similar statistically significant drops ( p < 0.05). Global and regional cerebral blood flow were also decreased 30%, 66%, 64% and 63% at the same experimental stages ( p < 0.05, ANOVA). CPB procedure with 60 min of DHCA significantly alters the blood viscoelasticity, global and regional cerebral blood flow. These large changes in viscoelasticity may have a significant impact on organ blood flow, particularly in the brain.

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