Which of the following signs observed on a mechanically ventilated patient indicate that suc-cessful weaning is unlikely?

1. Palpable scalene muscle use during inspiration
2. Palpable abdominal tensing during expiration
3. Presence of an irregular breathing pattern
4. Patient unable to alter breathing pattern on command
a. 2 and 4 only
b. 1, 2, and 3 only
c. 3 and 4 only
d. 1, 2, 3, and 4

ANS: D
Evaluation of patients for the presence of palpable scalene muscle use during inspiration, an ir-regular ventilatory pattern, palpable abdominal muscle tensing during expiration, and inability to alter ventilatory pattern on command can be helpful in assessment of the potential for prolonged spontaneous ventilation.