Driving pressure during proportional assist ventilation: an observational study

Area of Science:

• Critical Care Medicine
• Respiratory Physiology
• Mechanical Ventilation

Background:

• Driving pressure is a key factor in ventilator-induced lung injury during mechanical ventilation.
• Monitoring driving pressure during assisted ventilation may help identify at-risk patients.
• This study aimed to describe driving pressure patterns in critically ill patients on assisted ventilation.

Purpose of the Study:

• To characterize the occurrence and timing of high driving pressure in critically ill patients receiving assisted ventilation.
• To assess the relationship between driving pressure, tidal volume, and respiratory system compliance.
• To identify predictors of high driving pressure during assisted ventilation.

Main Methods:

• Prospective study of 62 critically ill patients on proportional assist ventilation (PAV+).
• Continuous recording of ventilator parameters for up to 72 hours.
• Driving pressure calculated as tidal volume divided by respiratory system compliance; analysis of high driving pressure events (≥15 cmH2O) and stable compliance periods.

Main Results:

• Driving pressure was <15 cmH2O for 95% of the time; high driving pressure events were typically brief (median 2.5 min).
• Prolonged high driving pressure occurred in 8% of patients; sustained high driving pressure with tidal volume ≥8 mL/kg was rare (1.6%).
• High driving pressure was strongly associated with low respiratory system compliance (<30 mL/cmH2O).

Conclusions:

• Sustained high driving pressure occurs in a small but significant proportion of critically ill patients on PAV+.
• High driving pressure was not linked to high tidal volume but predominantly occurred with low respiratory system compliance.
• Respiratory system compliance <30 mL/cmH2O is a strong indicator for potential high driving pressure during assisted ventilation.