What condition is detected at the end of the expiratory phase that allows for estimation of alveolar pressure?

The condition that is detected at the end of the expiratory phase, allowing for estimation of alveolar pressure, is auto-PEEP.

Auto-PEEP, also known as intrinsic PEEP, occurs when there is incomplete expiration before the next breath begins. This can happen in patients with obstructive lung diseases where air trapping occurs due to narrowed airways. At the end of the expiratory phase, if there remains a positive pressure in the thoracic cavity, this indicates that there is residual volume of air, which reflects a higher alveolar pressure than expected. Clinicians can assess this condition through measurements obtained during mechanical ventilation or through clinical signs seen during spontaneous breathing.

In contrast, PEEP is a mode of mechanical ventilation that applies pressure at the end of expiration to keep the alveoli open and is not a condition detected in the same context as auto-PEEP. Hypercapnia refers to an excess of carbon dioxide in the bloodstream, which can be a result of poor ventilation but does not provide a direct measurement of alveolar pressure. Asynchrony refers to a mismatch between the patient’s breathing pattern and the ventilator settings, which can lead to ineffective ventilation but is not specifically about measuring alveolar pressures at the end of expiration.