A life support was a system that helped support life when people could not hold up the strength of life by themselves.
The mad Kaled scientist Davros used a special chair to sustain his life after he became crippled from the Thousand Year War on Skaro. The primary life support system was controlled from a switch on his chair. (TV: Genesis of the Daleks) When Davros was dying, he augmented his own life support by a system that linked him to every Dalek on Skaro, their lives sustaining his. (TV: The Witch's Familiar)
Dalek casings contained life support chambers which housed the Dalek mutants. (PROSE: Remembrance of the Daleks)