O Doutor, como todos os Galifreyanos, pode prender a respiração por muito tempo (mais de dez a quinze minutos) usando seu famoso " Sistema de Derivação Respiratória ", um traço evolutivo que ele usou em várias ocasiões para evitar gases, para evitar sufocar e ignorar cheiros strongs:
Da TV: Os Robôs da Morte
LEELA: Doctor, why didn't the helium make your voice go squeaky?
DOCTOR: Because I'm a Time Lord. I've been around, you know. Two hearts, respiratory bypass system. I haven't lived seven hundred and fifty years without learning something. After you. Little mouse.
De TV: As cavernas de Androzani
DOCTOR: I can store oxygen for several minutes, Jek. Now, you must do everything you can to keep her temperature down until I get back.
JEK: Doctor, wait! I have just one oxygen cylinder left. I used it when I went into the baking chambers of the refinery. It will run out in minutes, but it might help.
Da Prosa: Uma cidade chamada eternidade
They dragged him the short distance to the gallows outside the jailhouse and then they hoisted him up. They watched him swing for a full quarter of an hour, with him too weak even to struggle or choke, before they cut him down.
The undertaker had fled the moment the Doctor spoke to him. Unsurprising, really, thought the Doctor, rubbing his bruised throat. Unfortunately, most victims of a lynch mob didn't have a respiratory bypass system to fall back on. On Gallifrey, hangings were less a form of justice, more a risky hobby for seedy Cardinals with regenerations to spare.