Nokea
During artificial ventilation in a patient with chronic obstructive pulmonary disease, air trapping:
Correct Answer: A
Rationale: Air trapping in COPD during mechanical ventilation occurs due to incomplete exhalation from airway obstruction, leading to intrinsic positive end-expiratory pressure (auto-PEEP). This increases intrathoracic pressure, compressing the vena cava and reducing venous return, which can cause hypotension a critical complication. A capnogram failing to plateau suggests prolonged exhalation, consistent with air trapping, but it's a diagnostic sign, not a consequence. A low respiratory rate allows more exhalation time, reducing air trapping, while decreasing the inspiratory-to-expiratory time ratio (e.g., shortening inspiration) similarly helps by extending exhalation. Positive end-expiratory pressure (PEEP) can exacerbate air trapping if excessive, but its effect depends on levels used. Hypotension from reduced venous return is a direct physiological result of severe air trapping, making it the most definitive statement in this context.