Lower transversal laparotomy has no appreciable effect on respiratory mechanics in guinea pigs.

Respiratory system, lung, and chest wall resistances and dynamic elastances were determined in six anesthetized, paralyzed, and mechanically ventilated guinea pigs both before and after lower transversal abdominal opening performed at the level of the spina iliaca anterosuperior. Furthermore, the resistances were also split into their two components, one reflecting the Newtonian resistances and the other representing the viscoelastic/inhomogeneous pressure dissipations in the system. The method of end-inflation occlusion during constant inspiratory flow was used. Chest wall configuration was also evaluated by measurements of lateral and anteroposterior diameters and circumferences at the 4th intercostal space and xiphoid levels both at functional residual capacity and at the end of tidal inspiration before and after surgery. After abdominal incision no statistically significant changes could be detected in any of the measured variables. It may be concluded that lower transversal abdominal opening does not alter respiratory mechanics.