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.

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 simulating 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, 0.092 +/- 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...

Mechanical and morphometrical changes in progressive bilateral pneumothorax and pleural effusion in normal rats.

Respiratory changes resulting from stepwise intrathoracic injections of 4 ml of either room air or warm (37 degrees C) Haemaccel, simulating pneumothorax and pleural effusion, respectively, were evaluated in anaesthetized, paralysed, and mechanically-ventilated rats. Respiratory system, lung, and chest wall resistances and elastances (static and dynamic) were determined in 14 animals. For this purpose, the end-inflation occlusion during constant inspiratory flow method was used. Chest wall configuration at both functional residual capacity (FRC) and end-inspiration tidal volume (i.e. FRC+(VT)) was also evaluated in: 1) 15 rats by measurements of lateral and anteroposterior diameters, and circumferences at the 3rd intercostal space and xiphoid levels; and 2) in 16 rats by measurements of thoracic cephalocaudal diameter. In addition, changes in functional residual capacity were measured. Both in pneumothorax and pleural effusion, resistances were not altered, but static and dynamic respiratory system and lung elastances increased progressively. Morphometric changes were similar at both functional residual capacity and end-inspiration; however, whereas pleural effusion increased all diameters, pneumothorax did not modify lateral diameter. Functional residual capacity was decreased in both conditions. In conclusion, pneumothorax and pleural effusion induced similar mechanical changes, but thoracic configuration was differently affected, since lateral diameters were increased in pleural effusion only.