What is the fine-grained topic of the following text: However, since the machines and nebulizers that deliver the hyperbaric mist don’t claim to rearrange skin’s cellular structure or treat a disease, they’ve never actually undergone rigorous clinical trials to prove their effectiveness, so some dermatologists remain skeptical about whether extra bursts of oxygen can really provide anything more than a quick pick-me-up. Only return the topic.
Effectiveness and skepticism regarding skin treatment with hyperbaric mist machines and nebulizers