Respiratory Care Tomograph Makes Ventilation Visible

The PulmoVista 500 EIT is designed for use in the clinical routine to visualize--in real time and directly at bedside--the regional distribution of ventilation in the lungs, helping determine how different lung regions respond to therapeutic interventions. Advanced data acquisition techniques and sophisticated reconstruction algorithms are used to generate images, waveforms, and parameters, which enable the assessment and trending of both the regional distribution of ventilation and short-term changes of end-expiratory lung volume within the thoracic crosssection.

Patient preparation requires the positioning of a flexible nonadhesive belt with 16 integrated electrodes around the patient's chest; the electrodes apply a small current to the patient's body, and the resulting voltages change according to the amount of air in the lungs. Monitoring is possible for up to 24 hours, enabling a close watch to be kept on critical lung conditions and the effect of therapy changes. The data gleaned provides valuable information about the effects of endotracheal suctioning, tidal volume settings, positive end-expiratory pressure (PEEP) settings, recruitment maneuvers, and patient positioning. The information allows settings to be optimized so that lung regions remain open throughout the breath cycle, helping to avoid problems associated with cyclic recruitment. The PulmoVista 500 EIT is a product of Dräger Medical (Lübeck, Germany).

"With EIT, we can now see how ventilation of the lung changes and subsequently functionally evaluate the changes. This is the first time this type of assessment has been made available," said Professor Hermann Wrigge, MD, deputy director of the clinic and polyclinic for anesthesiology and intensive care at the University Hospital Leipzig (Germany), the first hospital in the world to use the PulmoVista 500 EIT.

EIT is a medical imaging technique in which the conductivity or permittivity of part of the body is inferred from surface electrical measurements. Typically, conducting electrodes are attached to the skin of the subject and small alternating currents are applied to some or all of the electrodes. The resulting electrical potentials are measured, and the process may be repeated for numerous different configurations of applied current. Applications include monitoring of lung function, detection of cancer in the skin and breast, and location of epileptic foci. The currents used are relatively small, below the threshold at which they would cause stimulation of nerves. The frequency of the alternating current is sufficiently high not to give rise to electrolytic effects in the body, and the Ohmic power dissipated is sufficiently small and diffused over the body to be easily handled by the body's thermoregulatory system.

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Dräger Medical
University Hospital Leipzig