Question:hard
A 10 Degree Centigrade decrease in temperature causes a decrease in cerebral metabolic rate by
A 10 Degree Centigrade decrease in temperature causes a decrease in cerebral metabolic rate by
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Cerebral metabolic rate falls about 6-7% per degree Centigrade, so a 10 degree Centigrade drop nearly halves it.
Updated On: Jul 8, 2026
- 10%
- 30%
- 50%
- 70%
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Recall the temperature and metabolism link.
Cooling any tissue slows its chemical reactions, and the brain is no exception, its oxygen use falls as its temperature falls.
Step 2: Use the per degree rule.
Clinical teaching gives a working number, about 6 to 7 percent fall in cerebral oxygen consumption for every 1 degree Centigrade the brain cools.
Step 3: Scale this up to 10 degrees.
Compounding a 6 to 7 percent fall over 10 separate degree steps does not simply add to 60 to 70 percent, because each step acts on an already reduced value. Working through the compounding gives a final metabolic rate close to half the starting value, so the drop over the full 10 degrees works out to about 50 percent.
Step 4: Connect this to practice.
This is exactly why cooling the brain by around 10 degree Centigrade during neurosurgery or after a cardiac arrest is described as roughly halving its oxygen needs, giving it better tolerance to a temporary drop in blood supply.
Step 5: Conclude, with a note on the source key.
The physiologically correct fall for a 10 degree Centigrade drop is about 50 percent. The scanned original marks 30 percent with an uncertain symbol next to it, which does not match the standard 6 to 7 percent per degree teaching, so the answer here is corrected to 50 percent.
\[ \boxed{50\%} \]
Cooling any tissue slows its chemical reactions, and the brain is no exception, its oxygen use falls as its temperature falls.
Step 2: Use the per degree rule.
Clinical teaching gives a working number, about 6 to 7 percent fall in cerebral oxygen consumption for every 1 degree Centigrade the brain cools.
Step 3: Scale this up to 10 degrees.
Compounding a 6 to 7 percent fall over 10 separate degree steps does not simply add to 60 to 70 percent, because each step acts on an already reduced value. Working through the compounding gives a final metabolic rate close to half the starting value, so the drop over the full 10 degrees works out to about 50 percent.
Step 4: Connect this to practice.
This is exactly why cooling the brain by around 10 degree Centigrade during neurosurgery or after a cardiac arrest is described as roughly halving its oxygen needs, giving it better tolerance to a temporary drop in blood supply.
Step 5: Conclude, with a note on the source key.
The physiologically correct fall for a 10 degree Centigrade drop is about 50 percent. The scanned original marks 30 percent with an uncertain symbol next to it, which does not match the standard 6 to 7 percent per degree teaching, so the answer here is corrected to 50 percent.
\[ \boxed{50\%} \]
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