Respiratory system, lung, and chest wall mechanics after longitudinal laparotomy in rats

Abstract

It has been demonstrated that respiratory resistance and elastance increase whilst the abdomen remains open during longitudinal laparotomy. We wished to determine whether changes also occur after abdominal closure in the same animal preparation. In 10 sedated, anaesthetized paralysed, and mechanically-ventilated rats (309±33 (SD) g), resistances and elastances of the respiratory system, lung, and chest wall were measured both before longitudinal laparotomy and directly after abdominal closure. Furthermore, the resistances were also split into their initial and difference components, the former reflecting the Newtonian resistances and the latter representing the viscoelastic/inhomogeneous pressure dissipations in the system. For this purpose, the end inflation occlusion during constant inspiratory flow method was used. After laparotomy, no statistically significant changes were found in elastances and resistances of the respiratory system, lungs and chest wall (paired Student's t-test, significance level=5%). It can be concluded that after midline xiphipubic laparotomy accompanied by bilateral ventro-dorsal infracostal incision, respiratory resistances and elastances were not different from those found in the control condition.