What is the least reliable weaning index?

a. Vital capacity (VC)
b. Maximum inspiratory capacity (MIP)
c. Minute ventilation (VE)
d. Rapid-shallow breathing index (f/VT)

ANS: A
With respect to the more traditional weaning indices, vital capacity can be highly variable, whereas MIP, minute ventilation, respiratory rate (f), and f/VT tend to be more reliable.