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Electrical impedance tomography (EIT) is a promising new tool for bedside monitoring of regional lung ventilation. Several studies have focused on the ventilation distribution and relationship with regional lung volume on a lower, caudal lung level. However, no information is available at a higher, cranial lung level.
EIT (EIT Evaluation Kit 2; Dräger, Lübeck, Germany) was measured at cranial and caudal lung levels in 10 patients after cardiothoracic surgery. Patients were fully sedated and mechanically ventilated and a PEEP trial was performed at four PEEP levels (15, 10, 5 and 0 cmH2O).
The center of gravity index decreased after lowering the PEEP level at both the caudal and cranial lung levels (Figure (Figure11 right). Whereas the tidal volume impedance variation divided by tidal volume increased at the cranial lung level and decreased at the caudal lung level during the step-wise reductions in PEEP (Figure (Figure11 left).
During decremental PEEP steps, the ventilation distribution not only shifts from a dorsal to ventral direction, but also from the caudal to cranial direction.