2006 OPEN FORUM Abstracts
THE DEVELOPMENT OF LIPOPOLYSACCCHARIDE INDUCED LUNG INJURY IN SWINE CAN BE MONITORED BY ELECTRICAL IMPEDANCE TOMOGRAPHY
Marcia Volpe RPT, Alexander Adams FAARC, RRT,
Joel Holger MD, John Marini
MD, Marcelo Amato MD. Healthpartners/Regions Hospital,
Background:
Electrical impedance tomography (EIT) provides dynamic images of ventilation by
comparing impedance differences between electrodes equi-positioned around the
mid-chest. Determining the degree and localization of gas/tissue ratios by EIT
allows active monitoring of the primary regions of pathophysiology and could
directly assist in PEEP titration. In a model of progressive lung injury
induced by lipopolysaccharide (LPS) infusion in swine, EIT was applied to
assess regional ventilation as injury developed.
Methods: Six (6) juvenile swine were deeply anesthetized in the
supine position for a LPS shock model study. A low-frequency electrical current
was transmitted between leads (32) positioned around the mid-chest to create
continuous impedance mapping of ventilation. An initial normal-ventilation
image was obtained and, during LPS infusion at 20 mgm/kg/hr for 5 hours, EIT
images were obtained at 30 min intervals. Subsequent analysis of the images
compared identical regions.
Results: A
significant decline in PaO2/FIO2 from 450 to
170 confirmed the developing lung injury. From an analysis of regional functional
impedance differences, ventilation shifted from a relative balance between
ventral and dorsal regions to predominantly ventral ventilation (figure). A
decrease in relative impedance change during the study and an increase in WW/DW
indicate that dorsal edema formation caused the shift.
Conclusions: Using continuous EIT imaging, a ventral/dorsal image
comparison can monitor developing lung injury.