A 65-year-old male with a history of COPD and active tobacco use with no prior intubations presented to the emergency department with increased work of breathing and increased wheezing. In the emergency department, he was given stacked nebulizers and IV steroids and initiated on BIPAP. His initial blood gas demonstrated:
Following intubation, he was placed on volume control ventilation. His initial peak pressure (peak inspiratory pressure [PIP]) was 45 cm H2O, and his plateau pressure (Pplat) was 35 cm H2O. He was placed on a respiratory rate of 30, PEEP 15, FiO2 0.40 and his SpO2 was 90%. Two hours after arrival to the ICU, his ventilator starts to alarm for high pressures. His peak pressures have increased to 65 cm H2O, and his plateau pressure has increased to 55 cm H2O. His heart rate increases from 80 beats per minutes to 110, and his blood pressure drops from 110/70 to 80/50 mm Hg. His SpO2 drops to 75%. His examination is notable for continual wheezing and slight deviation of the trachea toward the left.
What is the most likely cause for this acute change?
A. Worsening bronchoconstrictionCorrect Answer: B
The incidence of overt barotrauma in mechanical ventilation ranges from 4% to 15% COPD is commonly associated with pneumothoraxes, as these patients may have underlying bullous disease and can require high airway pressures to overcome bronchial obstruction. In this case, the patient had a baseline elevated plateau pressure which placed him at higher risk for developing overdistention leading to a pneumothorax. Given that both parameters changed, the underlying issue does not deal solely with resistance. If resistance had suddenly increased, for example, with worsening bronchoconstriction, the peak airway pressures would likely have increased without an increase in the plateau pressures. Along with the increases in both pressures, there was also evidence of hemodynamic changes concerning for a tension pneumothorax. As the lung collapses, intrathoracic pressure causes a shift in mediastinal structures toward the noncollapsed lung which can cause tracheal deviation on examination. Biting on the endotracheal tube could result in an increase in airway pressures, but it is unlikely to have severe hemodynamic effects. Abdominal distention can also cause an increase in peak and plateau pressures and, in the setting of abdominal compartment syndrome, could cause hypotension; however, this would be less likely to occur so acutely and less likely to be associated with tracheal deviation.
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