Objective: Prosthetic reconstruction of the chest wall may yield several respiratory changes. Nevertheless, to our knowledge, no comprehensive analysis of respiratory mechanics under this condition has been hitherto performed.
Methods: Respiratory mechanics were evaluated in two groups of rats. In one group (n=8), a polytetrafluoroethylene (PTFE) patch was used; in another group (n=8), a polypropylene mesh (Marlex) associated with methylmethacrylate (PPMM) was employed. All animals were sedated, anesthetized, paralyzed, and mechanically ventilated before and after the prosthetic reconstruction of the chest wall. After airway occlusion at end inspiration, respiratory system, pulmonary, and chest wall resistive pressures (ΔP1rs, ΔP1L, and ΔP1CW, respectively) and viscoelastic/inhomogenous pressures (ΔP2rs, ΔP2L, and ΔP2cw, respectively) were determined. Respiratory system, lung, and chest wall static (Estrs, EstL, and Estcw, respectively), and dynamic elastances (Edynrs, EdynL, and Edyncw, respectively), and the corresponding Δ elastances (ΔE, calculated as Edyn-Est) were also obtained.
Results: In both groups, significant increases in ΔP2rs, ΔP2cw, ΔErs, ΔEcw, Estrs, EstL, and Estcw were observed after chest wall reconstruction. However, ΔP2rs, ΔP2cw, ΔErs, ΔEcw, Estrs, and EstL were significantly higher in the PPMM group than in the PTFE group.
Conclusions: Prosthetic reconstruction of the chest wall yields not only elastic changes, but also there is also an important increase of pressure dissipated against viscoelastic/inhomogenous segments of the chest wall. Furthermore, taking into account respiratory mechanics, the PTFE patch might be preferred to the PPMM patch.