Respiratory mechanics after tube thoracostomy in rats

The purpose of the present study was to determine the mechanical respiratory profile after the insertion of a catheter into the pleural cavity of anesthetized, paralyzed, mechanically ventilated rats, thus stimulating the common use of chest tubes in clinical situations. Using the method of end-inflation occlusion during constant inspiratory flow in 7 adult Wistar rats, respiratory system, lung, and chest wall total resistance (0.353 +/- 0.058, 0.260 +/- 0.651, 0.091 +/- 0.012 (mean +/- SD) cmH2O.ml-1.s, respectively), viscous resistance (0.140 +/- 0.007, 0.100 +/- 0.007, 0.040 +/- 0.003 cmH2O.ml-1.s< respectively), and viscoelastic resistance (0.213 +/- 0.017, 0.160 +/- 0.022, 0.053 +/- 0.011 cmH2O.ml-1.s, respectively) as well as respiratory system, lung, and chest wall static elastance (4.51 +/- 0.27, 3.85 +/- 0.28, 0.66 +/- 0.12 cmH2O.ml-1, respectively), and dynamic elastance (5.72 +/- 0.24, 4.76 +/- 0.32, 0.96 +/- 0.17 cmH2O.ml-1, respectively) were not significantly modified after the insertion of a tube into the second right intercostal stage. We conclude that, under the present experimental conditions, a catheter inserted into the pleural space per se is not responsible for any alterations in respiratory mechanics.