Esophageal Balloon Manometry: Rounds Study Guide

1. The core idea

The ventilator only shows us airway pressure.

But airway pressure reflects pressure applied to the entire respiratory system:

• Lung
• Chest wall
• Abdomen
• Pleural space
• Patient effort

The esophageal balloon estimates pleural pressure using esophageal pressure, or Pes.

• In healthy individuals pleural pressure can be inferred from airway pressure. But in patients with sick lungs and poorly compliant chest wall, this becomes more difficult to infer.

Once we know pleural pressure, we can estimate transpulmonary pressure, or PL:

PL = airway pressure − pleural pressure

Practically:

PL = Paw − Pes

This matters because transpulmonary pressure is the pressure actually distending the lung.

So when we place an esophageal balloon, we are trying to answer:

Is the pressure I see on the ventilator actually stressing the lung, or is it being absorbed by the chest wall/abdomen?