Final answer:
A suction machine should not be used on skin affected by open wounds, burns, or conditions that result in fragile skin, as it could worsen the injury.
Step-by-step explanation:
A suction machine should not be used on skin with certain conditions due to the risk of causing harm. Specifically, a suction machine is generally considered unsafe for use on skin that is affected by open wounds, burns, or any condition that results in fragile skin.
These conditions make the skin more susceptible to injury, and the negative pressure created by a suction machine could potentially worsen the situation by causing further damage to the already compromised skin tissue. It's always recommended to consult a healthcare professional before using a suction machine on any compromised skin condition.