A comparison of methods to identify open-lung PEEP

Area of Science:

• Critical Care Medicine
• Respiratory Physiology
• Mechanical Ventilation

Background:

• Setting appropriate positive end-expiratory pressure (PEEP) after lung recruitment maneuvers (RM) is crucial for managing Acute Respiratory Distress Syndrome (ARDS).
• Numerous methods exist in the literature for optimizing PEEP following RM, necessitating a comparative analysis.

Purpose of the Study:

• To compare ten published parameters for determining optimal PEEP levels in an animal model of ARDS after a lung recruitment maneuver.
• To identify which PEEP-setting parameters yield consistent and reliable results in this specific clinical context.

Main Methods:

• Acute lung injury was induced in sheep via lung lavage.
• A quasi-static pressure-volume (P-V) curve was generated, followed by a lung recruitment maneuver (RM).
• A decremental PEEP trial was conducted, comparing measured parameters with those from the P-V curve.

Main Results:

• Parameters such as maximum dynamic tidal respiratory compliance, maximum PaO2, and minimum shunt during the decremental PEEP trial were statistically similar.
• The lower Pflex and point of maximal compliance increase (Pmci,i) on the inflation limb of the P-V curve also yielded indistinguishable PEEP values.
• Conversely, deflation Pflex and minimum PaCO2 values differed significantly from other parameters.

Conclusions:

• In this ARDS animal model, dynamic tidal respiratory compliance, maximum PaO2, maximum PaO2 + PaCO2, minimum shunt, inflation lower Pflex, and Pmci,i provide comparable PEEP values post-RM.
• These findings suggest a consensus among several key physiological parameters for guiding PEEP selection after lung recruitment.