Positive end-expiratory pressure titration at bedside using electrical impedance tomography in post-operative cardiac surgery patients

Background: Post-operative positive end-expiratory pressure (PEEP) setting to minimize the risk of ventilator-associated lung injury is still controversial. Assessment of regional ventilation distribution by electrical impedance tomography (EIT) might be superior as compared with global parameters. The aim of this prospective observational study was to compare global dynamic compliance (CRS ) with different EIT indices during a short clinical applicable descending PEEP trial.

Methods: Twenty mechanically ventilated patients after elective cardiac surgery received a standard recruitment manoeuvre (RM) following descending PEEP trial in steps of 2 cmH2 O from PEEP 14 cmH2 O to 6 cmH2 O. During baseline and all PEEP steps, CRS was assessed and regional ventilation distribution was measured by means of EIT. The individual 'best' PEEP values for the derived EIT indices and CRS were calculated and compared.

Results: The descending PEEP trial lasted less than 10 min. CRS increased after the RM and showed a maximum value at PEEP 8 cmH2 O. Ventilation distribution shifted more to dependent lung regions after RM and back to more non-dependent regions during the PEEP trial. Individual 'best' PEEP by CRS showed significantly lower values than 'best' PEEP by ventilation distribution measured with EIT indices.

Conclusion: During a short descending PEEP trial at bedside, EIT is capable of following the status of regional ventilation distribution in ventilated patients. The 'best' PEEP value identified by individual maximum CRS was lower than optimal PEEP levels as determined by means of EIT indices. EIT could help setting PEEP in post-operative ventilated patients.