A patient is intubated due to an acute exacerbation of chronic obstructive pulmonary disease (COPD)

The patient is now breathing with pressure support ventilation 5 cm H2O and continuous positive airway pressure (CPAP) 5 cm H2O. The patient is unable to flow trigger every inspiration. Unin-tended positive end-expiratory pressure (auto-PEEP) is measured at 10 cm H2O. The most ap-propriate action to take is which of the following?
a. Decrease the CPAP to 3 cm H2O.
b. Increase the CPAP to 8 cm H2O.
c. Increase pressure support to 10 cm H2O.
d. Change the flow trigger setting to 1 L/min.

ANS: B
Patients may have trouble triggering a breath when unintended positive end-expiratory pressure (auto-PEEP) is present. When this occurs, adjusting the sensitivity may not alleviate the patient's inability to trigger the ventilator. When auto-PEEP occurs in mechanically ventilated, spontane-ously breathing patients with airflow obstruction, setting extrinsic PEEP to a level equal to about 80% of the patient's auto-PEEP level may allow the ventilator to sense the patient's inspiratory efforts. Decreasing the extrinsic PEEP level will not alleviate this problem. Altering the pressure support or the flow trigger will not alleviate this problem.