Anesthesia Knowledge Test 24 (AKT-24) Practice

Endobronchial intubation involves the placement of the endotracheal tube into one main bronchus, usually intentionally for surgical reasons or to isolate a lung for better ventilation control. When this occurs, it can lead to a decrease in the partial pressure of oxygen in the arterial blood (PaO2) due to a reduction in ventilation to one lung.

When ventilation is preferentially directed to one lung only, the other lung is effectively deprived of fresh gas flow. This can lead to inadequate oxygenation from the non-ventilated lung and contribute to a lower overall PaO2. In this scenario, the ventilated lung might not provide enough oxygen to compensate for the shunted blood that passes through the non-ventilated lung, which can further exacerbate hypoxemia.

Additionally, if the lung that is bypassed has a degree of shunting or poorly functioning alveoli, this can result in mixing of deoxygenated blood with the oxygenated blood from the ventilated lung, leading to even lower PaO2 levels. Thus, the reduction in overall ventilation when one lung is preferentially ventilated leads to decreased oxygen delivery, explaining the decrease in arterial oxygen levels associated with endobronchial intub