The effect on ventilatory function of fixation of a flail segment in internal (FIP) and external (FEP) position and oxygen administration was studied in an experimental flail chest with pleural indemnity. Variations of tidal volume (TV), respiratory rate (RR), minute volume (MV), and arterial blood gases are reported. These parameters were measured in nine dogs in control and flail conditions (FC). The effect of FIP, FEP, and oxygen administration were studied.
Results: Significant differences were found: TV decreased from control values to FC and from FC to FIP, but increased from FC to FEP. RR values increased from control to FC and from FC to FIP, but decreased from FC to FEP. MV values decreased from FC to FEP. TV, RR, and MV were not changed under oxygen administration. Hypoxemia or hypercapnia were not observed. It was concluded that FIP is deleterious for respiratory mechanics, whereas FEP improves ventilatory parameters.