Which of the following conditions are common reasons for SBT failure? I. respiratory drive failure II. oxygenation failure III. cardiovascular failure IV. muscle failure

A. I, IV only
B. II, III only
C. I, III, IV only
D. I, II, III, IV

ANS: D
A. Incorrect response: See explanation D.
B. Incorrect response: See explanation D.
C. Incorrect response: See explanation D.
D. Correct response: Common causes for failure of ventilator discontinuation are (1) respiratory drive failure: inability to generate a reliable respiratory drive because of central nervous system depression or the presence of sedative or neuromuscular blockade; (2) oxygenation failure: rapid hemoglobin desaturation from loss of expiratory pressure and/or Fio2; (3) cardiovascular failure: dysrhythmias and/or hypotension from catechol release, edema formation, or coronary hypoxemia caused by the loss of ventilatory support; and (4) muscle failure: muscle overload from abnormal respiratory system impedances in the setting of weakened, fatigued, or metabolically disturbed muscles.