Transpulmonary pressure and lung elastance can be estimated by a PEEP-step manoeuvre

Area of Science:

• Mechanical Ventilation
• Respiratory Physiology
• Critical Care Medicine

Background:

• Transpulmonary pressure is crucial for protective mechanical ventilation.
• Esophageal pressure measurement is essential but rarely used clinically.
• A simplified method for transpulmonary pressure monitoring is needed.

Purpose of the Study:

• To compare tidal and positive end-expiratory pressure (PEEP) inflation in the respiratory system.
• To determine if PEEP inflation can be used to assess transpulmonary pressure.
• To investigate a simpler method for monitoring protective ventilation.

Main Methods:

• 12 patients with acute respiratory failure underwent PEEP trials (0-16 cmH2O).
• Changes in end-expiratory lung volume (ΔEELV) were measured using tidal volume differences.
• Esophageal pressure was monitored using a balloon catheter.

Main Results:

• End-expiratory esophageal pressure did not significantly increase with PEEP.
• Increase in EELV correlated with PEEP changes divided by lung elastance (ΔPEEP/El).
• Transpulmonary pressure derived from PEEP and EELV showed high correlation (r²=0.80) with esophageal pressure measurements.

Conclusions:

• PEEP inflation is slow, allowing respiratory system adaptation.
• Transpulmonary pressure changes are equal to PEEP changes during PEEP inflation.
• Transpulmonary pressure can be determined without esophageal pressure monitoring, simplifying protective ventilation.