Table 1.

Definitions/subtypes of futility

Physiological futility	Treatment that cannot achieve its physiological aim [25]
Quantitative futility	Treatment that has <1% chance of succeeding [16]
Qualitative futility	Treatment that cannot achieve an acceptable quality of life [26]; treatment that merely preserves unconsciousness or fails to relieve total dependence on intensive medical care [16]
Imminent demise futility	An intervention that will not change the fact that the patient will die in the near future [26]
Lethal condition futility	The patient has an underlying condition that will not be affected by the intervention and which will lead to death within weeks to months [26]