Electrical impedance tomography is able to track changes in respiratory function in endotoxin-challenged rodents.
OBJECTIVE
In order to assess and optimize the effect of new therapies for acute lung injury (ALI) in rodent models, a monitoring technique that continuously assesses the functional state of the lung is mandatory. Electrical impedance tomography (EIT) has been suggested as a technique for quantifying lung inflammation in ALI. However, EIT has not been evaluated in a rodent model of ALI.


METHODS
EIT measurements were compared in ventilated Sprague-Dawley rats (n = 14), randomly subjected to intratracheal administration of endotoxin (LPS) or saline (control). Lung mechanics, lung weight wet/dry ratio and inflammatory markers in bronchoalveolar lavage fluid were also evaluated.


RESULTS
LPS caused a significant decrease in lung compliance and TLC as compared with control (-42.0%, P = 0.04, and -27.9%, P = 0.02, respectively). These changes were paralleled by differences in mean impedance changes as detected by EIT (Spearman's rank correlation coefficient: rho = 0.66 and 0.73, respectively, P < 0.01). LPS increased the lung weight wet/dry ratio (6.35 +/- 0.42 vs 5.15 +/- 0.07, P = 0.003), and the bronchoalveolar lavage total WCC (8.96 +/- 1.87 vs 1.16 +/- 0.10 x 10(9)/L, P = 0.002) as compared with control. The lung weight wet/dry ratio was inversely related to the mean impedance change (rho = -0.76, P < 0.01).


CONCLUSIONS
This study has demonstrated for the first time that eight-electrode EIT readily tracks the inflammatory response of lung tissue in a rodent model of ALI. EIT may thus provide a promising, non-invasive technique for monitoring the time-course of ALI in rodent models, and for testing novel pharmacological strategies to counter it.
Herber-Jonat
Susanne
S
Division of Neonatology, University Children's Hospital, Perinatal Center, Ludwig-Maximilian-University Munich, Grosshadern, Munich, Marchioninistr.15, Munich D-81377, Germany. susanne.herber-jonat@med.uni-muenchen.de
Hajek
Kerstin
K
Mittal
Rashmi
R
Just
Anita
A
Hahn
Günter
G
Schulze
Andreas
A
Flemmer
Andreas W
AW
D055371:Acute Lung Injury / Q000139:chemically induced* / Q000503:physiopathology*; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid; D004195:Disease Models, Animal; D004566:Electrodes; D004731:Endotoxins / Q000009:adverse effects* / Q000494:pharmacology; D008168:Lung / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D009929:Organ Size / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015656:Respiratory Mechanics / Q000502:physiology; D014054:Tomography / Q000379:methods*; D014109:Total Lung Capacity / Q000502:physiology
D004731:Endotoxins