Tidal ventilation distribution during pressure-controlled ventilation and pressure support ventilation in post-cardiac surgery patients

• Published in: Acta anaesthesiologica Scandinavica 2014-09, Vol.58 (8), p.997-1006
• Main Authors: BLANKMAN, P., VAN DER KREEFT, S. M., GOMMERS, D.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Cardiac Surgical Procedures; Cross-Over Studies; Diaphragm - physiopathology; Electric Impedance; Female; Heart surgery; Humans; Injuries; Lung - physiopathology; Male; Middle Aged; Point-of-Care Systems; Positive-Pressure Respiration; Pressure; Prospective Studies; Pulmonary Ventilation; Respiration, Artificial - methods; Tidal Volume; Ventilator-Induced Lung Injury - prevention & control; Ventilators
• ISSN: 0001-5172; 1399-6576
• DOI: 10.1111/aas.12367

Background Inhomogeneous ventilation is an important contributor to ventilator‐induced lung injury. Therefore, this study examines homogeneity of lung ventilation by means of electrical impedance tomography (EIT) measurements during pressure‐controlled ventilation (PCV) and pressure support ventilation (PSV) using the same ventilation pressures. Methods Twenty mechanically ventilated patients were studied after cardiac surgery. On arrival at the intensive care unit, ventilation distribution was measured with EIT just above the diaphragm for 15 min. After awakening, PCV was switched to PSV and EIT measurements were again recorded. Results Tidal impedance variation, a measure of tidal volume, increased during PSV compared with PCV, despite using the same ventilation pressures (P = 0.045). The distribution of tidal ventilation to the dependent lung region was more pronounced during PSV compared with PCV, especially during the first half of the inspiration. An even distribution of tidal ventilation between the dependent and non‐dependent lung regions was seen during PCV at lower tidal volumes (