Decrease in lung volume depends on end-expiratory pressure in a rabbit model of airway lavage.
BACKGROUND
In the past, the rabbit model of repeated airway lavage has been extensively used to induce a decrease in lung volume accompanied by impairment in lung mechanics and gas exchange.


OBJECTIVE
The rationale of our study was to investigate the influence of different end-expiratory pressure (EEP) levels (0.4-4.2 cm H2O) on changes in functional residual capacity (FRC) and the efficacy of lavages administered.


METHODS
Forty-five rabbits were subjected to 2-8 lavages with 20 ml/kg warm normal saline until arterial/alveolar oxygen tension (a/A ratio) had decreased to </=0. 12.


RESULTS
FRC and dynamic compliance of the respiratory system (Crs) decreased significantly (both p < 0.001; from 19.1 +/- 4.2 to 10.5 +/- 5.6 ml/kg and from 1.17 +/- 0.27 to 0.47 +/- 0.10 ml/cm H2O, respectively, means +/- SD). The decrease in FRC was significantly influenced by EEP (-28.6 +/- 15.8% at EEP = 1 cm H2O vs. -58.7 +/- 12.9% at EEP = 3 cm H2O, p < 0.0001). There was a significant correlation between the number of lavages and EEP (p < 0.01), indicating that successive lavages at higher EEP became ineffective in lowering FRC compared to those at lower EEP.


CONCLUSIONS
We conclude that the EEP levels used in this model are of critical importance for the prediction of a decrease in lung volume (FRC) and the efficacy of lavages.
Krause
M F
MF
Children's Hospital, Albert Ludwigs University, Freiburg, Germany. krause@kkl200.ukl.uni-freiburg.de
Hoehn
T
T
D000818:Animals; D001158:Arteries; D001992:Bronchoalveolar Lavage Fluid; D005260:Female; D005652:Functional Residual Capacity / Q000502:physiology; D008168:Lung / Q000503:physiopathology*; D008170:Lung Compliance / Q000502:physiology; D008176:Lung Volume Measurements; D010100:Oxygen / Q000097:blood / Q000378:metabolism; D011312:Pressure; D011650:Pulmonary Alveoli / Q000378:metabolism; D011817:Rabbits; D012119:Respiration
D010100:Oxygen