Safe Inspiratory Pressures Threshold in Lung Recruitment Maneuvers: An In Vivo Neonatal ARDS Model

Area of Science:

• Neonatal critical care
• Respiratory physiology
• Experimental medicine

Background:

• Acute Respiratory Distress Syndrome (ARDS) in neonates presents significant management challenges.
• Understanding the pressure thresholds for adverse events during ventilation is critical for patient safety.

Purpose of the Study:

• To determine the specific levels of peak inspiratory pressure (PIP) and mean airway pressure that induce pneumothorax in an in vivo neonatal ARDS model.
• To analyze hemodynamic and cerebral responses to increasing intrathoracic pressure.

Main Methods:

• A prospective experimental study was conducted on 11 neonatal pigs (<48 hours old) with induced ARDS.
• Invasive monitoring of hemodynamics, intracranial pressure, and cerebral oximetry was performed.
• Positive End-Expiratory Pressure (PEEP) was incrementally increased until pneumothorax occurred, with data analyzed using descriptive and regression methods.

Main Results:

• Pneumothorax occurred at a median PEEP of 54 cm H2O and PIP of 65 cm H2O.
• Asystole was observed at a median PEEP of 49 cm H2O and PIP of 60 cm H2O.
• Hemodynamic changes began at lower pressures (PEEP 14 cm H2O, PIP 25 cm H2O), with cerebral compromise noted during severe hypotension and asystole.

Conclusions:

• Increasing PEEP in ARDS neonates did not lead to severe adverse events within commonly used pressure ranges.
• Pneumothorax, asystole, and cerebral compromise manifest at high intrathoracic pressure levels.
• Close hemodynamic monitoring is essential during lung recruitment maneuvers as adverse effects can emerge early at clinically relevant pressures.