Critical Care Medicine-Neurologic Disorders>>>>>Mechanical Ventilation
Question 2#

A 32-year-old man with severe asthma is admitted to the ICU with an acute asthma exacerbation. He is intubated, paralyzed, and mechanically ventilated. His ventilator settings are:

His ABG on these settings is:

On day 2 of his ICU stay, an end-expiratory hold maneuver is performed and his airway pressure is measured at 15 cm H2O. Several hours later, he is noted to have progressive tachycardia, and his blood pressure has decreased from 120/90 to 75/55 mm Hg. A chest radiograph demonstrates similar findings to the prior day, without evidence of new infiltrate or pneumothorax.

What is the best next step in management? 

a. Briefly disconnect the mechanical ventilator from the endotracheal tube
b. Perform a needle decompression at the second intercostal space
c. Perform an emergent bronchoscopy
d. Increase the respiratory rate on the ventilator
e. Decrease the set PEEP on the ventilator

Correct Answer is A

Comment:

Correct Answer: A

The patient has developed hemodynamic instability as a result of intrinsic PEEP, or dynamic hyperinflation, which increases intrathoracic pressure and decreases venous return. This is a life-threatening complication that requires immediate release of trapped gas from the lungs; this is best accomplished by disconnecting the ventilator circuit for a brief period of time (answer A is correct). Intrinsic PEEP can be very common in patients with obstructive lung disease on the ventilator.

Without evidence of pneumothorax on radiograph, ultrasound, or other high suspicion, a needle decompression is not warranted (answer B is incorrect). Bronchoscopy is occasionally utilized to clear mucous plugging in patient with severe asthma, however this would not explain the patient’s hemodynamic instability (answer C is incorrect). An increase in the respiratory rate will decrease the patient’s expiratory time and lead to worsening gas trapping (answer D is incorrect). A decrease in the extrinsic PEEP set on the ventilator will not decrease intrinsic PEEP and will not improve this patient’s hemodynamics (answer E is incorrect).

Reference:

  1. MacIntyre NR, Cheng KC, McConnell R. Applied PEEP during pressure support reduces the inspiratory threshold load of intrinsic PEEP. Chest. 1997;111(1):188.