Doctors said veteran long-distance swimmer Diana Nyad's tongue and lips are swollen as she makes the final push for the Florida coast.
Dr Kot and Dr Covington, part of Ms Nyad's support team, said her speech is slurred as a result of the swelling.
Although they are concerned about the 64 year old's airways, they have not intervened in her attempt at swimming from Cuba to Florida without a shark cage.
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ITV News spoke to Nick Channing-Williams who described the freezing conditions on board the car ferry that caught fire earlier today.
A widespread frost will affect the UK due to plummeting temperatures along with a lingering fog in several areas.
Members of the Queen's Guard have been assigned the protection of armed police, amid reports they could be targeted by terrorists.