Intraoperative PEEP selection by pressure-based capnography: a proof of concept study.

Area of Science:

• Mechanical Ventilation
• Respiratory Physiology
• Critical Care Medicine

Background:

• Determining optimal positive-end expiratory pressure (PEEP) after lung recruitment maneuvers (RM) is crucial for maintaining lung aeration.
• Traditional methods rely on respiratory compliance (Crs) measurements, which can be complex to interpret.
• A novel approach using barometric capnography (BCap) has been proposed to simplify PEEP determination.

Purpose of the Study:

• To evaluate a new barometric capnography (BCap) method for determining positive-end expiratory pressure (PEEP) after a recruitment maneuver (RM).
• To compare the PEEP determined by BCap (PEEP(BCap)) with the PEEP determined by the standard method based on respiratory compliance (PEEP(Crs)).
• To explore the association between PEEP(BCap) and end-expiratory transpulmonary pressure (PEEP(PL)).

Main Methods:

• A comparative study involving eleven anesthetized patients undergoing mechanical ventilation.
• A recruitment maneuver (RM) was performed, followed by slow expiration with simultaneous BCap and pressure-volume (PV) curve monitoring.
• PEEP(BCap) was identified at the point of change in the slope of phase III of the BCap curve.
• PEEP(Crs) was determined at the point of maximal respiratory compliance during a slow PV curve.

Main Results:

• PEEP(BCap) was 8.5(3.3) cmH2O, which was not statistically different from PEEP(Crs) of 10.0(4.0) cmH2O (p=0.72).
• A strong correlation was observed between PEEP(BCap) and PEEP(Crs) (Rho=0.84, p<0.001), with a bias of 0.19 cmH2O.
• PEEP(BCap) also showed strong correlation with PEEP(PL) (Rho=0.93, p<0.001), with a bias of -0.3 cmH2O.

Conclusions:

• Barometric capnography (BCap) is a feasible method for detecting lung collapse during mechanical ventilation.
• The BCap method provides a reliable alternative for determining optimal positive-end expiratory pressure (PEEP) after recruitment maneuvers.
• BCap offers a potentially simpler and effective approach compared to traditional compliance-based methods.