A 60-year-old man is being weaned from a ventilator in the ICU. The likelihood that weaning is going to fail is suggested by the presence of which of the following?
A respiratory rate of 24 breaths/min A PaO2 of 80 mm Hg on FiO2 of 40% A vital capacity (VC) of 5 mL/kg body weight A minute ventilation of 8 L/min