End-Inspiratory transpulmonary pressure is calculated as which of the following?

End-Inspiratory transpulmonary pressure is calculated as which of the following?

• A. Paw - Pes
• B. PEEP - Pes
• C. Pplat - Pes
• D. Pes - Pplat

Answer: (C)

Transpulmonary pressure is the distending pressure across the lung, calculated as alveolar pressure minus pleural pressure. At the end of inspiration, with an inspiratory hold, there is no airflow, so the alveolar pressure equals the plateau pressure. If we estimate pleural pressure with esophageal pressure, the end-inspiratory transpulmonary pressure becomes Pplat minus Pes. This value specifically reflects the pressure applied to the lung tissue at the end of inspiration. Using the peak airway pressure (Paw) would mix resistance and dynamic flow effects and does not represent the static end-inspiratory state. End-expiratory transpulmonary pressure uses PEEP minus Pes, not end-inspiratory. And subtracting Pes from Pplat (Pes - Pplat) would invert the relationship and is not how transpulmonary pressure is defined.

Transpulmonary pressure is the distending pressure across the lung, calculated as alveolar pressure minus pleural pressure. At the end of inspiration, with an inspiratory hold, there is no airflow, so the alveolar pressure equals the plateau pressure. If we estimate pleural pressure with esophageal pressure, the end-inspiratory transpulmonary pressure becomes Pplat minus Pes. This value specifically reflects the pressure applied to the lung tissue at the end of inspiration.

Using the peak airway pressure (Paw) would mix resistance and dynamic flow effects and does not represent the static end-inspiratory state. End-expiratory transpulmonary pressure uses PEEP minus Pes, not end-inspiratory. And subtracting Pes from Pplat (Pes - Pplat) would invert the relationship and is not how transpulmonary pressure is defined.