At which point in the ventilatory cycle should the pulmonary artery occlusive pressure be assessed?

The pulmonary artery occlusive pressure (PAOP), also known as pulmonary capillary wedge pressure, is most accurately assessed at the end of expiration. This timing is crucial because it reflects the hemodynamics of the left atrial pressure without the interference caused by intrathoracic pressure changes during the inspiratory phase.

During the inspiratory phase, the pressure in the thoracic cavity decreases, which can lead to transient changes in the measured pressures, including PAOP. By measuring it at the end of expiration, you capture a more stable and accurate representation of the left atrial pressure since the influences of the respiratory cycle have evened out. It's during this phase that the lungs are at a resting state, providing a clearer picture for assessing cardiac function and fluid status.

Thus, assessing PAOP at the end of expiration allows for the most reliable and consistent readings, vital for effective patient management in critical care settings.