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Effect of hypothermia on cellular membrane function during low-flow extracorporeal circulation
Surgery
|August 1, 1987
Summary
Hypothermia during cardiopulmonary bypass can worsen skeletal muscle cell damage, particularly under low-flow conditions. This study reveals that low-flow hypothermic bypass impairs muscle cell membrane function, similar to shock.
Area of Science:
- Physiology
- Cellular Biology
- Cardiovascular Surgery
Background:
- Systemic hypothermia aids recovery from hypoperfusion and circulatory arrest.
- Cellular changes in skeletal muscle during hypoperfusion are known, but the effects of coexistent hypothermia are less understood.
Purpose of the Study:
- To investigate the impact of combined low-flow and hypothermia on skeletal muscle cellular function during cardiopulmonary bypass (CPB).
Main Methods:
- Nine dogs underwent total cardiopulmonary bypass (CPB) with nonpulsatile flow.
- Three perfusion models were used: normal-flow/hypothermic (23°C), low-flow/normothermic (37°C), and low-flow/hypothermic (23°C).
- Skeletal muscle cellular function was assessed by measuring resting transmembrane potential difference (Em) and tissue electrolyte distribution.
Main Results:
- Low-flow/hypothermic CPB significantly depolarized resting Em and increased intracellular sodium ([Na]i) and the Na+/K+ permeability ratio (pNa/pK).
- Normal-flow/hypothermic CPB maintained resting Em, while low-flow/normothermic CPB caused intermediate depolarization without altering [Na]i or pNa/pK.
- Cellular membrane alterations in low-flow/hypothermic CPB resemble those seen in hemorrhagic shock.
Conclusions:
- Low-flow/hypothermic CPB induces significant alterations in skeletal muscle cellular membrane function.
- These changes suggest that hypothermia does not prevent, and may exacerbate, flow-related skeletal muscle derangements during CPB.