Controversies in pediatric perfusion / test 3 / 3 Flashcards
pH stat strategy
Aim:
Total CO2 content:
Intracellular state:
Enzyme structure & function:
Aim: Constant pH
Total CO2 content: Increases
Intracellular state: Acidotic
Enzyme structure & function: Altered & decreased activity
Alpha - Stat strategy
Aim:
Total CO2 content:
Intracellular state:
Enzyme structure & function:
Aim: Constant OH/H+
Total CO2 content: Constant
Intracellular state: Neutral
Enzyme structure & function: Normal & activity is maximized
Anaerobic metabolism produces what?
Lactic Acid
Normoxia with Alpha Stat management leads to what ?
Increased Acid production
Hyperoxia with pH Stat management leads to what ?
Decreased Acid production
GUCHs ?
Grown Up Congenital Hearts
By keeping total CO2 stores constant, net protein charge states are kept constant as temperature changes, this regulation is termed ?
Alpha-Stat Management
net protein charge states ?
(termed “alpha”)
The “alpha” refers to an important charged species ?
the alpha imidazole ring on the histidine amino acid
Normal protein structure and function, especially enzyme function, depends on what ?
a constant and usually neutral electrochemical environment
Alpha-stat management maintains a PaCO2 level of ?
40 mmHg when measured at 37° C
Temperature uncorrected
Advantages of Alpha-Stat Management ?
- Neutral Intracellular electrochemical neutrality
- Maintains a more normal cerebral flow/metabolism
relationship. - Limited luxuriant cerebral blood flow during CPB
Disadvantages of Alpha-Stat Management ?
less effective cooling of the brain =
↓ suppression of cerebral metabolism =
↓ cerebral protection
pH-Stat Management
pH-stat management keeps the pH constant when measured at the actual blood temperature
potent cerebral vasodilator during nonpulsatile cardiopulmonary bypass.
CO2
Because CO2 solubility increases with temperature, total body CO2 stores must be what while using pH Stat Management ?
increased during cooling to maintain a “normal” corrected value.
pH-stat management maintains a PaCO2 level of 40 mmHg when measured at ?
actual blood temperature
Temperature corrected
Advantages of pH-Stat Management ?
-Luxuriant cerebral perfusion
-Improved brain cooling
Especially in the presence of aortopulmonary collaterals or shunts
Disadvantages of pH-Stat Management
- Luxuriant cerebral flow may increase embolic material to the brain
> Cerebral flow/metabolism uncoupling - Less intracellular electrochemical neutrality (Acidic environment)
Describe the Combination Strategy ?
CPB Initiation:
Prior to DHCA:
During DHCA:
Rewarming:
CPB Initiation: pH Stat
Prior to DHCA: pH Stat
During DHCA: Alpha Stat
Rewarming: Alpha Stat
The use of pH-stat strategy during initial cooling to 14 C followed by a switch to Alpha-Stat strategy just before arrest results in ?
A better recovery of cerebral metabolism after DHCA compared with the recovery with either strategy used alone.
What gas management strategy is utilized mainly for pediatrics ?
Combination Strategy
electrochemical charge states and binding are largely responsible for what?
maintaining normal protein conformational structure
What kind of gas management would improve brain cooling in patients with Aortopulmonary collaterals or shunts ?
pH Stat Management
