Observing for half an hour is a common practice in surgery when facing some uncertain factors.
Especially the observation of blood circulation, which involves the oxygen and nutrient supply to organs and related tissues, cannot be immediately assessed.
For example, when the limbs are bitten by venomous snakes or spiders, the correct approach is to tightly bind the wound near the heart to block blood circulation. The purpose is to prevent the venom from entering crucial parts like the heart and central nervous system through blood circulation.
Many people don't know that if limbs are bound tightly for more than half an hour, they should be loosened briefly before re-binding.
Because ischemia in the limbs for over half an hour can easily lead to irreversible necrosis.
Similarly, during the delicate observation of blood circulation in certain inconspicuous organs and tissues, continual observation for over half an hour is necessary to ensure safety.
