Niki Lauda may not be able to return to the Formula 1 circuits anytime soon.
Recently, as he recovers in intensive care from a lung transplant, the F1 legend's surgeon said that Lauda should be able to return to "normal life" eventually.
However, Osterreich claims that the Mercedes team chairman had a setback over the weekend, when he had to be connected to a dialysis machine.
The 69-year-old has since improved, but Osterreich says that he will not be able to travel by plane for six months.
Lauda has been told to holiday only in "neighbouring countries" so that he can return quickly to the hospital in Vienna if need be.